Fireballs and Meteorites - SOTT.NET

October 2009

noreply@blogger.com (Keit) — Wed, 28 Oct 2009 05:05:00 +0000

Video: Fireball lights up sky over Iceland

mbl.is
Mon, 05 Oct 2009 16:43 EDT

A police dash-cam catches a fireball lighting up the sky in the south of Iceland

Translation of article:

The police in Selfoss caught these weird lights in the sky on tape shortly after midnight last night. The officers were going east during a routine highway patrol on Eyrarbakka-road when they noticed a spectacular flare which to them seemed to be heading to the river Ölfusá. Speculations are that this was a meteorite entering the atmosphere.

Many saw the flare and notified the police, and the flare was seen all around the south of Iceland and in Akranes. It is believed impossible to have been an emergency flare.

The sheriff in Selfoss says there has not been any aftermath to his knowledge, and no unusal visitors have been seen that could possibly have fallen from the sky.

Quick Rebound From Marine Mass Extinction Event, New Findings Show

Science Daily
Sat, 03 Oct 2009 19:55 EDT

© Don Davis/NASA
An artist's rendering of the asteroid impact that took place 65 million years ago and likely killed off nearly every large vertebrate species on the planet, including, many think, the dinosaurs.

In 1980, Luis Alvarez and his collaborators stunned the world with their discovery that an asteroid impact 65 million years ago probably killed off the dinosaurs and much of the the world's living organisms. But ever since, there has been an ongoing debate about how long it took for life to return to the devastated planet and for ecosystems to bounce back.

Now, researchers from MIT and their collaborators have found that at least some forms of microscopic marine life - the so called "primary producers," or photosynthetic organisms such as algae and cyanobacteria in the ocean - recovered within about a century after the mass extinction. Previous research had indicated the process might have taken millions of years.

It has taken so long to uncover the quick recovery because previous studies looked mostly at fossils in the layers of sediment from that period, and apparently the initial recovery was dominated by tiny, soft-bodied organisms such as cyanobacteria, which do not have shells or other hard body parts that leave fossil traces. The new research looked instead for "chemical fossils" - traces of organic molecules (compounds composed of mostly carbon and hydrogen) that can reveal the presence of specific types of organisms, even though all other parts of the organisms themselves are long gone.

The new research, published in the Oct. 2 issue of Science, was led by Julio Sepúlveda, an MIT postdoc who carried out part of the work while still a graduate student at the University of Bremen, Germany, and MIT Professor of Geobiology Roger Summons, among others.

The team had two major advantages that helped to make the new findings possible. One was a section of the well-known cliff face at Stevns Klint, Denmark, that happens to have an unusually thick layer of sediment from the period of the mass extinction - about 40 centimeters thick, compared to the few cm thickness of the layers that Alvarez originally studied from that period at Gubbio (Italy) and Stevns Klint (Denmark). And team members tapped one of the most powerful Gas Chromatograph-Mass Spectrometers (GC-MS) in the world, a device that can measure minute quantities of different molecules in the rock. MIT's advanced GC-MS is one of only a few such powerful instruments currently available at U.S. universities.

When people look at microfossils in the sediments from the period but are unable to detect the chemical biomarkers with the level of sensitivity the MIT team was able to achieve, they "miss a big part of the picture," Sepúlveda says. "Many of these microorganisms" that were detected through molecular signatures "are at the base of the food chain, but if you don't look with biochemical techniques you miss them."

The analysis clarified the sequence of events after the big impact. Immediately after the impact, certain areas of the ocean were devoid of oxygen and hostile to most algae, but close to the continent, microbial life was inhibited for only a relatively short period: in probably less than 100 years, algal productivity showed the first signs of recovery. In the open ocean, however, this recovery took much longer: previous studies have estimated that the global ocean ecosystem did not return to its former state until 1 to 3 million years following the impact.

Because of the rebound of primary producers, Sepúlveda says "very soon after the impact, the food supply was not likely a limitation" for other organisms, and yet "the whole ecology of the system remained disrupted" and took much longer to recover.

The findings provide observational evidence supporting models suggesting that global darkness after the impact was rather short. "Primary productivity came back quickly, at least in the environment we were studying," says Summons, referring to the near-shore environment represented by the Danish sediments.

"The atmosphere must have cleared up rapidly," he says. "People will have to rethink the recovery of the ecosystems. It can't be just the lack of food supply" that made it take so long to recover.

The team hopes to be able to study other locations with relatively thick deposits from the extinction aftermath, to determine whether the quick recovery really was a widespread phenomenon after the mass extinction.

These findings seem to rule out one theory about how the global ecosystem responded to the impact, which held that for more than a million years there was a "Strangelove ocean" - a reference to the post-apocalyptic scenario in the movie Dr. Strangelove - in which all the primary producers remained absent for a prolonged period, Summons says.

In addition to Sepúlveda and Summons, the work was carried out by Jens Wendler of the Friedrich-Schiller University in Jena, Germany, and Kai-Uwe Hinrichs of the University of Bremen. The work was funded by the DFG, European Graduate College Europrox and the NASA Astrobiology and Exobiology Programs.

Journal reference:

1. Julio Sepúlveda, Jens E. Wendler, Roger E. Summons, and Kai-Uwe Hinrichs. Rapid Resurgence of Marine Productivity After the Cretaceous-Paleogene Mass Extinction. Science, 2009; DOI: link

Zadunaisky's Math Determined Halley's Comet Orbit

Associated Press / Boston.com
Wed, 07 Oct 2009 20:20 EDT

Buenos Aires, Argentina - Pedro Elias Zadunaisky, an Argentine astronomer and mathematician whose calculations helped determine the orbit of Saturn's outermost moon, Phoebe, as well as Halley's Comet, died Wednesday. He was 91.

Zadunaisky was a pioneer in celestial mechanics, applying mathematical models to determine how gravity and other forces alter the orbits of other objects in the solar system.

Zadunaisky also was a Senior Astronomer at the Smithsonian Astrophysical Observatory and in the 1960s researched the orbits of celestial bodies at NASA's Goddard Space Flight Center, calculating the orbits of the first U.S. Earth satellite, Explorer I, as well as other satellites during the U.S. space race against Russia.

Born in the Argentine city of Rosario on Dec. 10, 1917, Zadunaisky earned a civil engineering degree at the National University of Rosario, then pursued applied mathematics and specialized in celestial mechanics. He earned three Guggenheim fellowships for research at Columbia University in 1957, Princeton University in 1958 and at the University of Texas at Austin in 1977.

Zadunaisky left Argentina in 1966 along with many other professors and scientists after a crackdown on university protests against a military coup known as "the night of the long clubs."

Zadunaisky soon returned, and eventually taught at both the University of Buenos Aires and the National University of La Plata. He also directed astrodynamical investigations at Argentina's National Commission on Space Activity.

In 2000, an asteroid discovered by a team of his former students was named 4617 Zadunaisky in his honor.

His research was published in more than 40 publications worldwide, including the text book A Guide to Celestial Mechanics, edited by the Harvard Smithsonian Center for Astrophysics.

What (Maybe) Didn't Kill the Dinosaurs: Comets

John Matson
Scientific American
Thu, 01 Oct 2009 00:01 EDT

© Bettmann Corbis
Cometary commotion: A new mechanism for how icy bodies get past Jupiter and Saturn suggests that comet showers did not play a big role in Earth's extinctions.

A new model for comet production revises the theory of their origins

The chunks of ice and dust that make their home in the Oort cloud, far beyond the orbit of Pluto, sometimes become dislodged and head into the solar system as streaky comets. Some disruptions, caused by passing stars and other interactions with the Milky Way galaxy, are severe enough to send Oort comets into orbits that buzz or even collide with Earth. New simulations have revealed a novel mechanism for their entry into our part of the solar system, a method that also suggests that comet showers may not have been strongly involved in major extinctions on Earth.

Comet dynamics depend heavily on Jupiter and Saturn: their huge gravitational fields tend to keep objects away from Earth. Comets that manage to skirt Jupiter and Saturn, the conventional thinking goes, had to have originated in the outer reaches of the Oort cloud, where perturbations from outside the solar system can be felt most strongly and are writ large across vast cometary orbits that take hundreds of years to complete. Only during comet showers caused by close stellar passages, the theory holds, have extreme gravitational disruptions brought inner Oort cloud comets into the mix.

A computer simulation by Nathan Kaib and Thomas Quinn, both at the University of Washington, have upended this thinking. They have found that the comets that manage to cross the Jupiter-Saturn barrier do in fact originate in large numbers in the inner Oort cloud, even in the absence of a large disruption causing a comet shower. Specifically, they found that the relatively nearby objects of the inner Oort cloud can be kicked into the reaches of the outer cloud via interactions with the massive planets. Those newly far-flung comets, suddenly enjoying a longer orbit and greater gravitational perturbations from interstellar space, can find their orbits so changed that, by the time they pass through the planetary region again, they slip past the gas giants. "They can basically hop over the Jupiter-Saturn barrier," Kaib says.

Kaib and Quinn estimate that more than half of the comets we observe streaking in from the Oort cloud reach our neighborhood via this route, and other researchers agree the simulation appears valid. "This mechanism, this dynamical path, as we call it, could work and could be a significant contributor," says Paul Weissman, a senior research scientist at the NASA Jet Propulsion Laboratory.

The new research presents a route for comet production "that goes some way" toward resolving discrepancies between the standard model and the observations, says Scott Tremaine, an astrophysicist at the Institute for Advanced Study in Princeton, N.J. "One of the issues is that [the conventional view of] the cometary formation process is so inefficient; in order to produce the number of comets that we see, you'd need a really massive protoplanetary disk, one that appears to be incompatible with our best estimates from other sources," Tremaine says.

Kaib and Quinn used their newfound mechanism, as well as the number of observed comets, to estimate an upper limit on how much material could be in the inner Oort cloud. They then produced a statistical model of how many comets would have hit Earth in comet showers in the past several hundred million years. Their conclusion: large cometary showers were few and hence probably did not cause more than one extinction event.

Using cometary dynamics to unwind the extinction history on Earth will likely meet with some controversy. Weissman notes that the extinction implications of Kaib and Quinn's analysis would involve comet showers, not comets in general, and that even a diminished profile of showers does not rule out the role of comets in extinctions. One big strike, rather than a shower of small ones, is all that's needed to trigger extinctions, he points out.

NASA Refines Asteroid Apophis' Path Toward Earth

Jet Propulsion Laboratory
Mon, 12 Oct 2009 19:52 EDT

Pasadena, California -- Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036.

The Apophis asteroid is approximately the size of two-and-a-half football fields. The new data were documented by near-Earth object scientists Steve Chesley and Paul Chodas at NASA's Jet Propulsion Laboratory in Pasadena, Calif. They will present their updated findings at a meeting of the American Astronomical Society's Division for Planetary Sciences in Puerto Rico on Oct. 8.

"Apophis has been one of those celestial bodies that has captured the public's interest since it was discovered in 2004," said Chesley. "Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million."

A majority of the data that enabled the updated orbit of Apophis came from observations Dave Tholen and collaborators at the University of Hawaii's Institute for Astronomy in Manoa made. Tholen pored over hundreds of previously unreleased images of the night sky made with the University of Hawaii's 2.2-meter (88-inch) telescope, located near the summit of Mauna Kea.

Tholen made improved measurements of the asteroid's position in the images, enabling him to provide Chesley and Chodas with new data sets more precise than previous measures for Apophis. Measurements from the Steward Observatory's 2.3 meter (90-inch) Bok telescope on Kitt Peak in Arizona and the Arecibo Observatory on the island of Puerto Rico also were used in Chesley's calculations.

The information provided a more accurate glimpse of Apophis' orbit well into the latter part of this century. Among the findings is another close encounter by the asteroid with Earth in 2068 with chance of impact currently at approximately three-in-a-million. As with earlier orbital estimates where Earth impacts in 2029 and 2036 could not initially be ruled out due to the need for additional data, it is expected that the 2068 encounter will diminish in probability as more information about Apophis is acquired.

Initially, Apophis was thought to have a 2.7 percent chance of impacting Earth in 2029. Additional observations of the asteroid ruled out any possibility of an impact in 2029. However, the asteroid is expected to make a record-setting -- but harmless -- close approach to Earth on Friday, April 13, 2029, when it comes no closer than 29,450 kilometers (18,300 miles) above Earth's surface.

"The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL. "The public can follow along as we continue to study Apophis and other near-Earth objects by visiting us on our AsteroidWatch Web site and by following us on the @AsteroidWatch Twitter feed."

The science of predicting asteroid orbits is based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids.

NASA detects and tracks asteroids and comets passing close to Earth using both ground and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. Cornell University, Ithaca, N.Y., operates the Arecibo Observatory under a cooperative agreement with the National Science Foundation in Arlington, Va.

Cosmic Object Caught On Camera

koat.com
Tue, 13 Oct 2009 02:15 EDT

A New Mexico astronomer is hoping you can help solve a mystery.

He caught a spectacular fireball on video and he said you can help him track down what's left of it.

Thomas Ashcraft caught a cosmic fireball on camera. It flashed through the sky for about eight seconds just after 2 Friday morning.

"Probably originating in the vicinity of Taos, and then streaking across the sky to Wagon Mound or Springer area," said Ashcraft.

Ashcraft works in a lab the size of a small barn. He bought or built most of the electronics himself, except for a special camera on loan from Sandia Labs.

The camera looks like a parking lot surveillance camera except it's parking lot is the sky.

"Actually up to Denver, into Utah, into southwest Kansas, and northern Mexico," said Ashcraft.

The camera runs from dusk to dawn recording everything that flashes through the heavens. It's synched to a radio telescope that records the sound of the objects shredding the ionosphere.

"Maybe somebody recorded this on surveillance camera. So if there's other videos, then we might be able to triangulate and see if there's a meteorite that landed somewhere," said Ashcraft.

Thomas says that this fireball was created by something about the size of a filing cabinet, but he can spot something as small as this bolt burning through the atmosphere.

Asteroid is Actually a Protoplanet: Study of First High-resolution Images of Pallas Confirms

ScienceDaily
Tue, 13 Oct 2009 12:40 EDT

© Science/AAAS
Pallas's largest crater-like feature seen in the digital model (left) and from two perspectives: appearing face-on (upper right) and edge-on along the limb (lower right).

Britney E. Schmidt, a UCLA doctoral student in the department of Earth and space sciences, wasn't sure what she'd glean from images of the asteroid Pallas taken by the Hubble Space Telescope. But she hoped to settle at least one burning question: Was Pallas, the second-largest asteroid, actually in that gray area between an asteroid and a small planet?

The answer, she found, was yes. Pallas, like its sister asteroids Ceres and Vesta, was that rare thing: an intact protoplanet.

"It was incredibly exciting to have this new perspective on an object that is really interesting and hadn't been observed by Hubble at high resolution," Schmidt said of the first high-resolution images of Pallas, which is believed to have been intact since its formation, most likely within a few million years of the birth of our solar system.

"We were trying to understand not only the object, but how the solar system formed," Schmidt said. "We think of these large asteroids not only as the building blocks of planets but as a chance to look at planet formation frozen in time."

The research appears Oct. 9 in the journal Science.

"To have the chance to use Hubble at all, and to see those images come back and understand automatically this could change what we think about this object - that was incredibly exciting to me," Schmidt said.

Pallas, which is named for the Greek goddess Pallas Athena, lies in the main asteroid belt between the orbits of Jupiter and Mars. Schmidt likens it to the size of Arizona, her home state. The massive body is unique, she said, partly because "its orbit is so much different from other asteroids. It's highly inclined."

Hubble had tried to snap pictures of the round-shaped body before but came up short. So when the space telescope took images again in September 2007, Schmidt and her colleagues had several goals.

"We wanted to learn about Pallas itself - what its shape is like, what its surface is like, does it have large impact craters, does it have significant topography," she said.

With the Hubble images, Schmidt and her colleagues were able to take new measurements of Pallas' size and shape. They were able to see that its surface has areas of dark and light, indicating that the water-rich body might have undergone an internal change in the same way planets do.

Pallas wasn't just a big rock made of hydrated silicate and ice, they found.

"That's what makes it more like a planet - the color variation and the round shape are very important as far as understanding, is this a dynamic object or has it been exactly the same since it's been formed?" Schmidt said. "We think it's probably a dynamic object."

For the first time, Schmidt and her colleagues also saw a large impact site on Pallas. They were unable to determine if it was a crater, but the depression did suggest something else important: that it could have led to Pallas' small family of asteroids orbiting in space.

"It's interesting, because there are very few large, intact asteroids left," Schmidt said. "There were probably many more. Most have been broken up completely. It's an interesting chance to almost look into the object, at the layer underneath. It's helping to unravel one of the big questions that we have about Pallas, why does it have this family?"

Schmidt's co-authors include Peter C. Thomas, a senior researcher at Cornell University; James Bauer, a researcher with the Jet Propulsion Laboratory; J.Y. Li, a postdoctoral student at the University of Maryland; Schmidt's Ph.D. adviser, UCLA professor of geophysics and space physics Christopher T. Russell; Andrew Rivkin, a researcher at Johns Hopkins University; Joel William Parker, a researcher at the Southwest Research Institute in Boulder, Colorado; Lucy McFadden, a faculty member at the University of Maryland; S. Alan Stern of the Southwest Research Institute; Max Mutchler, a researcher at the Space Telescope Sciences Institute; and Chris Radcliffe, a digital artist in Santa Monica.

"When people think of asteroids, they think of 'Star Wars' or of tiny little rocks floating through space," Schmidt said. "But some of these have been really physically dynamic. Around 5 million years after the formation of the solar system, Pallas was probably doing something kind of interesting."

Asteroid isn't just a dry heap of rubble

Rachel Courtland
New Scientist
Mon, 12 Oct 2009 14:29 EDT

© NASA/ESA/J. Parker/SWRI/P. Thomas/Cornell U/L. McFadden/University of Maryland/M. Mutchler/Z. Levay/STScI
The largest asteroid, Ceres (shown), appears to contain a lot of water ice beneath its surface. Now ice has been detected on the surface of the asteroid 24 Themis, which lies about three times as far from the sun as Earth does.

Two independent teams have found what may be the first direct evidence of water ice on the surface of an asteroid. The discovery lends support to the idea that asteroids could have helped deliver water to the early Earth.

Asteroids are generally considered to be rocky, and comets icy. That's because ice in the early solar system is thought to have formed beyond a "snow line" lying somewhere between Mars and Jupiter. Asteroids forming beyond that boundary could contain ice.

But it is not clear how common ice might be in the main asteroid belt, because sunlight is expected to quickly vaporise ice on the surfaces of airless bodies that fly closer to the sun than Jupiter.

In 2008, however, Andrew Rivkin of Johns Hopkins University in Laurel, Maryland, and Joshua Emery of the SETI Institute in Mountain View, California, found hints that the asteroid 24 Themis, which sits in the main asteroid belt between Mars and Jupiter, could have water ice on its surface. The team found the water signal by measuring the spectrum of infrared light radiated by the object.

Now a second team has found the water ice signature using the same telescope, NASA's Infrared Telescope Facility in Hawaii.

The new observations suggest water ice, mixed with organic molecules, is "widespread on the surface of the asteroid", Humberto Campins of the University of Central Florida in Orlando reported at a meeting of the American Astronomical Society's Division of Planetary Sciences in Fajardo, Puerto Rico, last week.

Icy parent

That is surprising, since the asteroid's distance from the sun means it should lose about 1 metre of ice each year. "This ice is unstable, and therefore we need a process to explain why there is ice on the surface now," Campins said at the meeting.

One possiblity is that an icy object might have collided with 24 Themis, leaving behind a layer of ice. Alternatively, the ice could have been part of the asteroid's parent body, which is thought to have broken up about 2.5 billion years ago, producing a family of asteroids with orbits similar to that of 24 Themis.

In that case, the ice seen on the surface now would once have been buried beneath dust and rock that insulated it from the sun's heat and prevented it from escaping into space. Impacts could then have churned the surface to expose the ice.

Watery hints

Until now, the possibility of present-day water ice on asteroids has only been hinted at. The density of the mammoth main-belt asteroid Ceres suggests it contains a large amount of water ice, but no clear-cut sign of ice has been found on its surface.

"This Themis result is really nice because it's been confirmed by two independent groups," says Henry Hsieh of Queen's University Belfast in the UK, though he notes that the spectral evidence for ice may not be entirely water-tight.

"It's a messy region [of the spectrum] that's hard to observe," says Clark Chapman of Southwest Research Institute in Boulder, Colorado. "In some sense, it's a matter of judgment whether it's a hint of water ice or an almost certain detection or somewhere in between."

Still, Chapman says, he would not be surprised to see water ice on asteroids, adding that the distinction between comets, traditionally considered to be icy, and asteroids, which have been largely thought of as rocky, is becoming increasingly blurred.

Comet tails

In recent years, Hsieh and others have discovered a handful of main-belt asteroids with comet-like tails that could be created by sublimating ice.

These so-called "main-belt comets" are too distant and faint for astronomers to scan their spectra for signs of water ice. Two of the four detected so far are part of the same family of asteroids as 24 Themis, which is the family's largest member.

"What is most likely the case is that the parent body [of this family] was water-ice-rich, was broken up, and now the surface of its largest fragment, Themis, has been impact-excavated, revealing the ice that was once deep in a larger object," says Britney Schmidt of UCLA, who was not affiliated with Campins's study. "It is exciting to finally get a glimpse inside a water-rich body."

Mismatched isotopes

David Jewitt of UCLA, co-discoverer of the first main-belt comets, agrees. "These objects may hold ice and preserve a record of conditions at formation between the orbits of Mars and Jupiter," he told New Scientist.

The detection could also go a long way towards explaining how the Earth got its water. Soon after the solar system's formation, the sun's heat is thought to have broken apart most water molecules that lay close to the sun.

Comets, which formed far from the sun, have been proposed as an alternate way of delivering water to the Earth, but the relative amounts of different isotopes of hydrogen in the water on comets do not match up with Earth's. "If there was water in the asteroids, it could be enough to fill the oceans," Hsieh says.

North America Comet Theory Questioned

Rex Dalton
Nature News
Mon, 12 Oct 2009 10:00 EDT

© Vance Holliday
Sediments at the San Jon site, in eastern New Mexico, contained very low abundances of magnetic spherules said to be evidence of an impact.

No evidence of an extraterrestrial impact 13,000 years ago, studies say.

An independent study has cast more doubt on a controversial theory that a comet exploded over icy North America nearly 13,000 years ago, wiping out the Clovis people and many of the continent's large animals.

Archaeologists have examined sediments at seven Clovis-age sites across the United States, and did not find enough magnetic cosmic debris to confirm that an extraterrestrial impact happened at that time, says the report in the Proceedings of the National Academy of Sciences (PNAS). It is the latest of several studies unable to support aspects of the impact hypothesis.

In 2007, a team led by Californian researchers announced a theory that a comet or asteroid had exploded over the North American ice sheet, creating widespread fire and an atmospheric soot burst followed by a cooling period known as the Younger Dryas.

Sometime after this, the Clovis people, sophisticated large-animal hunters known for their spear points, mysteriously disappeared; the team linked their vanishing to the environmental effects of the proposed impact.

Key evidence came in the form of magnetic microspherules discovered in sediments at 25 locations, including eight Clovis-age sites. Richard Firestone, of Lawrence Berkeley National Laboratory in California, and his colleagues argued that the microspherules were remnants of cosmic debris from an explosion.

But in more than 18 months of sedimentary analysis, a team led by Todd Surovell, an archaeologist at the University of Wyoming in Laramie, was unable to detect microspherule peaks. Two of the seven sites the group studied were places where Firestone's team identified spherule peaks.

"I spent hundreds of hours at the microscope examining sediment samples," says Surovell, "and I didn't find any physical evidence to support their theory."

Standing firm

The other team isn't backing down. "Their study doesn't negate our hypothesis," says James Kennett, a palaeoceanographer at the University of California at Santa Barbara and one of Firestone's co-authors. Another co-author, avocational geophysicist Allen West of Prescott, Arizona, says that Surovell's group didn't use the correct technique to extract, identify and quantify the microspherules.

Several other groups have been unable to support important aspects of the comet theory.

In a PNAS article published in February, Jennifer Marlon, a doctoral geography student at the University of Oregon in Eugene, and her colleagues found no systematic burning of biomass - as would have occurred if continent-wide fires had happened - at the time of the Younger Dryas in pollen and charcoal records at 35 sites. And at the Ecological Society of America meeting in Albuquerque, New Mexico, in August, Jacquelyn Gill, a palaeoecology doctoral student at the University of Wisconsin-Madison, reported finding no evidence of massive burning in sediment cores taken from lake beds in Ohio and Indiana.

Kennett, however, calls these studies "flawed". In August, his team published a report saying they had found nanometre-sized diamonds, purportedly created during an impact, and soot in sediments dated to the Younger Dryas on Santa Rosa Island, off the coast of California.

More studies of the theory - both critical and supportive - are in the publishing pipelines at other journals.

Surovell's co-author Vance Holliday, an archaeologist at the University of Arizona in Tucson, and his colleagues have an article in press at Current Anthropology that says the archaeological and geochronological records don't support a collapse of Clovis people at the time of the purported impact.

Comment: For a more in-depth view, read: The Younger Dryas Impact Event and the Cycles of Cosmic Catastrophes - Climate Scientists Awakening

What Hit Earth in 1908 with the Force of 3,000 Atomic Bombs?

PhysOrg
Tue, 13 Oct 2009 00:00 EDT

There have been numerous theories proposed about what struck the taiga in central Siberia, causing millions of trees to topple over and many still-standing trees to lose all their branches. Many expeditions have looked for traces of what hit Earth and have not found much. There is no telltale meteor crater, and no clear evidence of a nuclear blast. In fact, at the epicenter, the trees were found to be still standing. Whatever hit Earth did not reach the ground. It exploded in the air above the ground.

In The Tunguska Mystery by Vladimir Rubtsov, the efforts put forth by generations of Russian scientists, technicians, and others are documented. What did they find? Was it a meteorite, as had first been thought? Was it an asteroid? Was it a comet? Some support the idea that this was not a "natural" event at all but one caused by the explosion of an alien spaceship trying to land on Earth. Is there any evidence for this? How did the Russian scientific and world community react to this theory?

The mystery has been very difficult to solve, but it is important - perhaps even urgent - to solve it. We live in a very violent universe, and we are extremely vulnerable to its vagaries. How can we prevent another "Tunguska" if we don't even know what it was? And next time, the event might not occur in a remote, barely inhabited region of Earth. It may take many thousands of lives and destroy whole cities.

Vladimir Rubtsov was born in 1948 in Kharkov, Ukraine. He received his Ph.D. degree in the Philosophy of Science from the Institute of Philosophy of the Academy of Sciences of the USSR, having defended in 1980 the doctoral thesis: "Philosophical and Methodological Aspects of the Problem of Extraterrestrial Civilizations," the first of its kind in the former USSR. Dr. Rubtsov has authored two monographs and some 120 scientific and popular science articles in the Soviet, post-Soviet and international press.

Scientists May Have Found First Direct Evidence of Water Ice on Asteroid's Surface

Thaindian News
Tue, 13 Oct 2009 14:32 EDT

Two independent scientific teams have found what may be the first direct evidence of water ice on the surface of an asteroid, a discovery that lends support to the idea that asteroids could have helped deliver water to the early Earth.

Asteroids are generally considered to be rocky, and comets icy. That's because ice in the early solar system is thought to have formed beyond a "snow line" lying somewhere between Mars and Jupiter.

Asteroids forming beyond that boundary could contain ice.

But, it is not clear how common ice might be in the main asteroid belt, because sunlight is expected to quickly vaporise ice on the surfaces of airless bodies that fly closer to the sun than Jupiter.

In 2008, however, Andrew Rivkin of Johns Hopkins University in Laurel, Maryland, and Joshua Emery of the SETI Institute in Mountain View, California, found hints that the asteroid 24 Themis, which sits in the main asteroid belt between Mars and Jupiter, could have water ice on its surface.

The team found the water signal by measuring the spectrum of infrared light radiated by the object.

Now, according to a report in New Scientist, a second team has found the water ice signature using the same telescope, NASA's Infrared Telescope Facility in Hawaii.

The new observations suggest water ice, mixed with organic molecules, is "widespread on the surface of the asteroid," said Humberto Campins of the University of Central Florida in Orlando.

That is surprising, since the asteroid's distance from the sun means it should lose about 1 metre of ice each year.

"This ice is unstable, and therefore we need a process to explain why there is ice on the surface now," said Campins.

One possibility is that an icy object might have collided with 24 Themis, leaving behind a layer of ice.

Alternatively, the ice could have been part of the asteroid's parent body, which is thought to have broken up about 2.5 billion years ago, producing a family of asteroids with orbits similar to that of 24 Themis.

"What is most likely the case is that the parent body (of this family) was water-ice-rich, was broken up, and now the surface of its largest fragment, Themis, has been impact-excavated, revealing the ice that was once deep in a larger object," said Britney Schmidt of UCLA.

"It is exciting to finally get a glimpse inside a water-rich body," she added.

Hunting Arctic Asteroid Impact With Hovercraft

Alexis Madrigal
Wired
Mon, 12 Oct 2009 17:43 EDT

Two polar scientists hot on the trail of an arctic mystery have a new tool for exploration: a hovercraft, specially outfitted for week-long trips over the ice with scientific instruments and solar panels.

Their quarry is a nearly 22,000 square-mile patch of disturbed Arctic sea floor that could be evidence of a massive asteroid strike. John Hall, a now-retired geoscientist, discovered the anomaly during his late-'60s graduate work aboard Fletcher's Ice Island, a huge berg U.S. scientists inhabited for several decades.

Since then, no scientific vessel has been back over the area to collect more data. The massive icebreakers that have crunched through the Arctic since the 1990s can't reach the spot, said Yngve Kristofferson, a scientist and explorer at the University of Bergen in Norway.

Kristofferson became intrigued with Hall's data and in 2004, the two of them met in Bergen to talk Arctic science from eight in the morning to 10 in the evening. At the end of their time together, they came to a decision: They needed a hovercraft.

Luckily, Hall is a partial heir to the fortune his grandfather made as head of the American Chicle Company, the trust that ran the American bubble gum game early in the 20th century, so he was able to buy the vehicle with private funds. A customized Griffon Hovercraft 2000TD, it is now going through the paces, hitting the Arctic from its home at Longyearbyen for the first time in 2008, and hoping to reach its full potential next spring.

Hall delivered a speech detailing the craft's capabilities and mission at Columbia University's Lamont Doherty Earth Observatory on Oct. 6.

"The neat thing with a hovercraft is that you drive with the same ease over 10 centimeter-thick ice as you do with five meter thick ice," Kristofferson told Wired.com.

Despite their futuristic reputation, hovercraft have been commercially available for decades. The concept is actually quite simple. A big engine or turbine pumps air into a rubber skirt that allows the vehicle to tread lightly on whatever it's touching. The R/H Sabvabaa, for example, weighs six tons but exerts no more pressure on any patch of ice than a seagull standing on one leg would by standing on it. The rest of the power from the engine is devoted to propulsion, allowing the craft to skip along at speeds up to 50 miles per hour.

For the strange terrain of the Arctic, it works perfectly, Hall and Kristofferson wrote in an article in the journal The Leading Edge in August.

"The craft has proved to be useful for a variety of scientific tasks," they wrote. "It appears more efficient than any other platform for ice-thickness measurements and oceanographic work."

Their hovercraft push comes as money has flooded into Arctic research. With Arctic ice melting, the nations adjacent to the ocean are rushing to stake their claims not just on the water, but on the oil and natural gas that lie under the sea floor, leading to calls to establish a National Park to protect the area.

The most fascinating target for the hovercraft is the area of very thick ice closer to Ellesmere Island and northern Greenland. Not even nuclear-powered icebreakers have ventured into the region. It was just Hall's good fortune to have been aboard the floating ice island doing research when it passed near this apparent sea floor anomaly. The duo, along with several other colleagues, described the discovery in a 2008 paper in the Norwegian Journal of Geology.

"The upper couple hundred meters of sediment at the bottom of the Arctic Ocean is just like a carpet that is draped over the topography except for these areas where 150 meters are just blown away and the seabed is severely deformed," Kristofferson said.

To Kristofferson and Hall, the evidence suggests that a pressure wave caused by a pieces of a large asteroid crashing into the Arctic Ocean created these strange features.

"Our working hypothesis is that the spectrum and scale of the observed disturbances are best explained as the effect of a shock wave generated by the impact of an extraterrestrial object," they wrote.

But the hypothesis remains just that without more data. The hovercraft works well, but with its on-board fuel, its range is limited to around 500 miles. For that reason, the scientists imagine they'll use a larger vessel as a base of operations.

"What we really want to do is go along with an icebreaker into the Arctic. You can greatly enhance the scientific output if you have a hovercraft. If you have more of them, even better," Kristofferson said. "We can go out and do our own science and be away for many days. If the icebreaker gets stuck, we're not stuck."

Still, both Hall and Kristofferson know they face an uphill battle to get other scientists to take both the hovercraft and asteroid impact ideas seriously.

"The task is to figure out the real message in the data - the dream challenge for any scientist," Kristofferson told the Lamont Doherty alumni magazine earlier this year. "So far, we have mostly met shaking heads, which just makes it more fun."

Meteor explodes over Groningen, Netherlands: Fireball seen from Belgium and Germany

Dutch News
Wed, 14 Oct 2009 16:51 EDT

Hundreds of people report seeing a spectacular fireball or meteorite over the Netherlands in Tuesday's clear evening skies.

The police emergency number, Dutch coastguard and KNMI weather bureau report dozens of phone calls about the meteorite, which was seen in Germany and Belgium.

'I was standing in front of my window when there was a bright flash of light and a white fireball in the sky fell apart into three smaller ones,' eyewitness Erik Alberts from Zuidbroek in Groningen province told Nos tv. 'Like fireworks. A few seconds later, perhaps half a minute, there was a low rumble and the windows shook.'

Astronomers digging for meteors in Grimsby, Western Ontario

Peter Downs
The Tribune / Sun Media
Wed, 07 Oct 2009 22:02 EDT

© University of Western Ontario
A composite photograph of the meteor that streaked across southern Ontario Sept. 25. It is believed meteorites landed in the Grimsby area.

Space rocks formed when the solar system was created billions of years ago are believed to have fallen to Earth near Grimsby in a fiery light show two weeks ago.

Astronomers will be digging through farmers' fields Thursday and Friday on the hunt for hunks of a meteor that blazed across the skies of southern Ontario Sept. 25 shortly after 9 p.m.

The beachball-sized meteor was first picked up by cameras operated by the University of Western Ontario's physics and astronomy department 100 kilometres above Guelph as the fireball streaked southeastward at a speed of about 75,000 km/h.

Astronomers at the university have traced the meteor's path and believe chunks of it may have landed above the escarpment within a 10-km radius of Grimsby.

"We're pretty certain something came down," said Phil McCausland, a postdoctoral fellow with the university's astronomy department.

"It's hard to put an X on the map and say, 'There,' because what happens is at the end of the fireball path the lights go out. There's no camera record of that."

It's likely small pieces of the meteor - anywhere between the size of a golf ball or a fist - made it through the atmosphere and hit the ground, he said.

"It could be dozens, it could be one or two. It's hard to say, but if it's one or two, they will be on the largish size - probably more than a kilogram."

Researchers are keen to find any of the meteorites because it's extremely rare to have their fall to Earth documented so well with photo evidence.

Based on all of the information already known about the rocks, it's possible for astronomers to determine which orbit they came from and learn more about the early history of the solar system.

"There's only a handful, perhaps a dozen, meteorites that have this kind of orbital information," McCausland said.

The rural area where the meteorites are believed to have landed is largely farmland with some forest.

McCausland has already spent several days over the past week searching for the rocks and interviewing landowners in the area.

He was expected to be back on the hunt again Thursday with other researchers.

"Even though the (cameras) we have narrows it down quite nicely, it's still a large area to search. We're still talking about 12 to 16 kilometres," he said.

Doug Welch, an astrophysicist at McMaster University, will be joining the search.

Welch monitors one of Western's meteor-seeking sky cameras at the Hamilton university.

The fireball that torched across the sky two weeks ago practically went directly overhead of the Hamilton camera.

"It's really spectacular. ... I've seen them live, but it's very rare for them to be this bright," he said.

Recovering meteorites that may have fallen gives researchers a rare opportunity to learn more about the formation of the solar system, he said.

"These are free samples from elsewhere in the solar system delivered to your door. We have sample-return missions that cost hundreds of millions of dollars."

Meteorologist and Grimsby resident Kerry-Ann Lecky Hepburn spends much of her spare time photographing the stars and planets.

But the night the fireball streaked towards Grimsby, she didn't have her camera trained on the sky. She was watching TV with her meteorologist husband in their home atop the escarpment.

"We saw a bright flash and thought, 'How can it be a thunderstorm. There shouldn't be any storms around.'"

A quick check online the following morning confirmed for Lecky Hepburn the bright light was a meteor.

"It would have been nice to see something other than just the bright flash," she said.

Researchers are calling for anyone who has found pieces of meteorite to contact them, as well as people in the area who witnessed the fireball.

Meteorites are typically dark, smooth on the surface, heavier than rocks of a similar size and able to attract magnets because of the metals they contain.

Under Canadian law, meteorites become the property of whoever owns the property where they are recovered.

Photos and video footage of the meteor can be found online.

Canada, Ontario: Grimsby meteorite found

The Standard
Thu, 15 Oct 2009 17:00 EDT

The Grimsby space rock has been found.

A fragment of meteorite the size of a golf ball smashed in the windshield of a Grimsby family's sport utility vehicle on Sept. 25, according to a media release from the University of Western Ontario.

Astronomers released a video Oct. 7 of a blinding meteor streaking across the skies of Southern Ontario three weeks ago, estimating pieces may have landed in Grimsby or West Lincoln.

Meteorite hunters have been scouring the area ever since.

A press conference to discuss the find is scheduled for Friday morning.

US: Meteorite streaks across New Mexico sky

Gadi Schwartz and Matthew Kappus
KOB.com
Mon, 12 Oct 2009 17:20 EDT

Scientists think a fireball that flew over New Mexico may have been close enough to actually hit the ground.

A Santa Fe astronomer was able to catch the fiery streak on video. Thomas Ashcraft says the fireball didn't disintegrate when it hit the atmosphere. It may have landed somewhere near Taos.

"If we can get other camera angles, than we can put all the positions together and possibly hunt for an important--scientifically important--meteorite," he said.

The event was also captured by cameras at Sandia National Labs. Scientists estimate the meteor was about the size of a basketball all the way up to that of a small car.

Scientists at Sandia think it disintegrated over Chaco Canyon.

Giant Impact Near India - Not Mexico - May Have Doomed Dinosaurs

ScienceDaily
Thu, 15 Oct 2009 05:00 EDT

A mysterious basin off the coast of India could be the largest, multi-ringed impact crater the world has ever seen. And if a new study is right, it may have been responsible for killing the dinosaurs off 65 million years ago.

© Geological Society Of America
Three-dimensional reconstruction of the submerged Shiva crater (~500 km diameter) at the Mumbai Offshore Basin, western shelf of India from different cross-sectional and geophysical data.

Sankar Chatterjee of Texas Tech University and a team of researchers took a close look at the massive Shiva basin, a submerged depression west of India that is intensely mined for its oil and gas resources. Some complex craters are among the most productive hydrocarbon sites on the planet. Chatterjee will present his research at this month's Annual Meeting of the Geological Society of America in Portland, Oregon.

"If we are right, this is the largest crater known on our planet," Chatterjee said. "A bolide of this size, perhaps 40 kilometers (25 miles) in diameter creates its own tectonics."

By contrast, the object that struck the Yucatan Peninsula, and is commonly thought to have killed the dinosaurs was between 8 and 10 kilometers (5 and 6.2 miles) wide.

It's hard to imagine such a cataclysm. But if the team is right, the Shiva impact vaporized Earth's crust at the point of collision, leaving nothing but ultra-hot mantle material to well up in its place. It is likely that the impact enhanced the nearby Deccan Traps volcanic eruptions that covered much of western India. What's more, the impact broke the Seychelles islands off of the Indian tectonic plate, and sent them drifting toward Africa.

The geological evidence is dramatic. Shiva's outer rim forms a rough, faulted ring some 500 kilometers in diameter, encircling the central peak, known as the Bombay High, which would be 3 miles tall from the ocean floor (about the height of Mount McKinley). Most of the crater lies submerged on India's continental shelf, but where it does come ashore it is marked by tall cliffs, active faults and hot springs. The impact appears to have sheared or destroyed much of the 30-mile-thick granite layer in the western coast of India.

The team hopes to go India later this year to examine rocks drill from the center of the putative crater for clues that would prove the strange basin was formed by a gigantic impact.

"Rocks from the bottom of the crater will tell us the telltale sign of the impact event from shattered and melted target rocks. And we want to see if there are breccias, shocked quartz, and an iridium anomaly," Chatterjee said. Asteroids are rich in iridium, and such anomalies are thought of as the fingerprint of an impact.

Mars Rover Spots Another Meteorite

Space.com
Mon, 12 Oct 2009 17:10 EDT

NASA's intrepid Mars rover Opportunity has found yet another meteorite on the surface of the red planet.

Opportunity stumbled upon this new meteorite, dubbed "Shelter Island," less than three weeks after driving away from a larger meteorite that the rover examined for six weeks.

The rover began its approach to the meteorite with a 92-foot (28-meter) backwards drive on Oct. 1, the rover's 2,022nd day on Mars.

Opportunity and its twin rover Spirit - which is currently embedded in a soft spot of soil called Troy - have been on the Martian surface for more than five years.

Shelter Island is a pitted rock is about 18.5 inches (47 cm) long. The meteorite was first detected in images taken two Martian days earlier. (A Martian day is 24 hours and 40 minutes long.)

Two Martian days after its backward drive, Opportunity turned around to face the meteorite. In the days that followed, it made a final 3.3-foot (1-meter) move to put the rock within reach of the rover robotic arm . Mission managers are now planning to use the arm to contact the meteorite and make measurements.

Opportunity has driven about 2,300 feet (700 meters) since it finished studying the meteorite called "Block Island" on Sept. 11, 2009.

Block Island weighs at least half a ton, is composed of iron and nickel, and is likely too large to have plunged through the current thin atmosphere of Mars without being obliterated upon impact, scientists say.

Both meteorites have been found during Opportunity's trek to its next target, Endeavour Crater.

Opportunity also found a third meteorite, Heat Shield Rock, in 2004.

Video: Grimsby, Ontario meteor 25 September

TheSpec.com
Fri, 16 Oct 2009 10:41 EDT

Comment: You can read a report of this sighting here

UK: Red-hot piece of "space junk" crashes through pensioner's roof

The Daily Mail
Fri, 16 Oct 2009 10:43 EDT

Pensioner Peter Welton was amazed when a piece of red-hot debris crashed through his roof in July. Now experts have confirmed the object had travelled hundreds of miles from outer space.

The 75-year-old had been in his bedroom when he heard a smash and found the football-sized lump of extra terrestrial debris in the loft of his home in Hull.

The great-grandfather said: 'It was a hell of a shock. If it had landed in the street and hit anybody it would have killed them.'

As it was too hot to handle he brought it downstairs using oven gloves.

The 4lb dark grey object was removed by Humberside Police before being taken away by the Ministry of Defence for investigation.

Mr Welton and wife Mair, 62, then received a phone call from the RAF, who said the metal mass was most likely to be space junk. This could mean anything from part of a spacecraft to a piece of abandoned satellite.

Comment: And how about a meteorite? After all, considering the increasing frequency of 'falling rocks' reports, they are past due to be incorporated into daily weather forecasts.

RAF spokesman Squadron Leader Jeff Brock confirmed the finding, which was the first the RAF's Defence Flying Complaints Investigation Team had encountered.

He said: 'Following consultations with the European Space Agency and Nasa, we are confident the object is more than likely space debris which was orbiting in excess of a decade.

'This is the first bit of space debris that we have got our hands on - we have never until this occasion had anything relating to it at all.'

The DFCIT, based in Henlow, in Bedfordshire, investigates complaints related to military flying. Experts initially thought the object may have come from an aircraft.

However, its size and appearance was found to be 'entirely consistent' with space junk, and its heavy mass meant it was more likely to have been in a state of decaying orbit for a decade or more.

Russia (then the Soviet Union) put the first object into space just 51 years ago - Sputnik One. Since then we have created a swarm of perhaps tens of millions of items of space junk. The debris ranges in size from paint flecks to defunct satellites.

The oldest piece of space junk still circling is the Vanguard 1 communications satellite that was launched by the U.S in 1958, but stopped working in 1964.

Most hug close to the surface, 200-300 miles up in low-earth-orbit, where they are a hazard to telescopes and the astronauts on the International Space Station.

Most debris will eventually burn up in the atmosphere, but larger objects can reach the ground intact. Most have come down over the Pacific Ocean or sparsely populated areas.

There has only been one recorded incident of a person being hit by human-made space debris. In 1997, Lottie Williams from Oklahoma was hit in the shoulder by a 5.1" piece of blackened metal. It was later confirmed to be part of the a rocket fuel tank launched the year before. Luckily she was not injured.

Despite narrowly escaping being hit, Mrs Mair said she was excited to hear the experts' findings.

'I think it's wonderful,' she said.

Mail's online video report on the event

Canada, Ontario: Small meteorite broke windshield of SUV

Mark McNeil
The Hamilton Spectator
Fri, 16 Oct 2009 11:36 EDT

Scientists say a golf ball-sized rock that smashed through the windshield of an SUV is a meteorite, possibly from a spectacular fireball that streaked across the sky above Hamilton three weeks ago.

University of Western Ontario researchers confirmed the rock was a meteorite. It will be unveiled today at a media conference.

The fireball was captured on video Sept. 25 by a network of cameras administered by Western that regularly watch the skies at night. One of the cameras is located at McMaster University.

For the past two weeks, a search team headed by Phil McCausland, a postdoctoral fellow at Western's Centre for Planetary Science and Exploration, has been scouring the Grimsby area after working out mathematical models that suggest the fireball crashed there.

McCausland believes there are other meteorites on the ground that have yet to be found because the meteor weighed as much as a tonne when it hit Earth's atmosphere.

He returned to Grimsby yesterday with a search team of a few people looking around the residential area where the meteorite was discovered by a Grimsby resident.

"It was a very unusual rock, so the finder just held onto it," McCausland said. "They began to think it was a meteorite after the media coverage happened."

He would not be specific about where the rock was located, only that it was "just barely" within the 12-square-kilometre area south of the town of Grimsby that searchers were focusing on.

Tests are being done to try to find out more about the 50-gram object.

The discovery, he said, has buoyed enthusiasm that other pieces will be found and it will turn out to be a major find for the astronomy community.

Meteorites are relatively common, but it is highly unusual to find one from a meteor videotaped coming through the atmosphere.

"You don't stop when you find one piece. You keep going," said McCausland. "Finding one is confirmation that something came down here and there are probably many others."

They are looking intensively in the area of the first find because "meteorites don't care where they land. They could hit a house, a roof. They can end up anywhere."

mmcneil@thespec.com

905-526-4687

Hundreds See 'Exploding Fireball' in Sky

Trak.in News/Asian News International
Mon, 19 Oct 2009 00:00 EDT

Washington - Reports indicate that hundreds of people in the Netherlands and Germany have reported seeing a huge exploding fireball in the sky on October 13.

According to a report in National Geographic News, amateur photographer Robert Mikaelyan captured the phenomenon on camera.

Mikaelyan managed to capture several shots of the fireball as it swung low over the northern city of Groningen, Netherlands, and began to break apart into smaller chunks.

"I suddenly saw a light in the sky coming fast and quickly got the pictures taken," Mikaelyan said.

A few seconds after the fireball had been sighted, witnesses heard a sonic boom followed by low rumbles that rattled windows-signatures of a high-altitude explosion.

The object was most likely a rogue space rock that disintegrated shortly after hitting Earth's atmosphere, according to experts, who speculate that pieces of the meteor may have landed in the North Sea.

"Indeed it was a huge event," said Theo Jurriens, of the Kapteyn Astronomical Institute at the University of Groningen.

Earth is constantly being bombarded by smaller debris from comets, asteroids, and even other rocky planets in the solar system.

But a fireball of this size and brightness is likely seen anywhere in the world only every 20 to 25 years, according to Jurriens.

Comment: Every 20-25 years? Somebody's not been paying attention. These are from the past 3 weeks:

October 9th: Caught on camera: Meteorite streaks across New Mexico sky

October 5th: Video: Fireball lights up sky over Iceland

Septmber 28th: Cosmic shock and awe: Fireball explodes over Argentina

September 25th: Spectacular Fireball filmed over Canada

Taiwanese amateur astronomer discovers new asteroid

Cheng Chi-feng and Sofia Wu
Central News Agency
Mon, 19 Oct 2009 19:05 EDT

Kaohsiung - An amateur astronomer who discovered an asteroid earlier this year presented a model of his new discovery to Kaohsiung Mayor Chen Chu Monday to share it with all residents of the southern Taiwan port city.

Tsai Yuan-sheng discovered the asteroid along with an assistant at the Lulin Observatory on Yushan, also known as Jade Mountain, March 20 and tentatively named it "Kaohsiung" after his hometown.

In August, the International Astronomical Union's Committee on Small Body Nomenclature (IAU's CSBN) -- an international organization responsible for the naming of asteroids and comets -- formally approved the designation and gave Tsai's discovery a permanent number "215080." It was the first asteroid discovered by an amateur Taiwanese astronomy buff to have won international recognition.

The asteroid, located between Mars and Jupiter, is similar in size to Kaohsiung International Airport. At perihelion, the closest point to the sun in its orbit, the asteroid is 350 million kilometers from the sun and at aphelion, its most distant point from the sun in its orbit, it is about 450 million kilometers from the sun.

It takes about four years for the newly identified asteroid to complete its orbit around the sun.

Tsai and Lin Chi-sheng, an astronomical observation assistant at Lulin Observatory, spotted the asteroid using highly advanced digital equipment.

Tsai recalled that he first detected that the body could both rotate around its own axis and circle the Sun and that its position coordinates varied each day.

"I then took photos of the object consecutively for analytical comparison and finally came to the conclusion that it was an asteroid that had never been documented before," Tsai recalled.

According to Tsai, most larger asteroids have been discovered and only small asteroids that cannot be detected with the naked eye are still left to be spotted with highly sophisticated instruments.

Tsai, 40, began to develop his interest in observing the stars while studying at a military preparatory school as a teenager. At the time, he was required to stand guard at night, and the long hours with nothing to do led him to fall in love with stargazing.

He later dropped out of the naval academy to pursue his hobby more freely. He now often takes his wife and children high into the mountains to observe the stars at night.

Tsai has documented 13 asteroids, but "Kaohsiung" is the only one to have been recognized by the IAU's CSBN.

"I was so jubilant to obtain international recognition of my latest discovery and thus decided to name it 'Kaohsiung' to honor my beloved homeland," Tsai said.

"I also want to share my happiness in discovering the new body with all fellow Kaohsiung residents, " Tsai said at the asteroid model presentation ceremony at the city's Gangho Elementary School.

For her part, Mayor Chen said the discovery of the asteroid and its designation as "Kaohsiung" are not only the "pride of Kaohsiung" but also the "pride of Taiwan." Noting that Tsai's achievement has inspired a "star chasing" fad in the city, Chen said the city government will step up efforts to promote astronomical education and cultivate more talent in the field.

Chen said she has directed the city's Bureau of Education to allocate NT$1 million (US$31,056) annually to help finance the operations of the Gangho Elementary School's astronomy observatory.

She also proposed that an astronomy-themed science park be established after Kaohsiung City and Kaohsiung County merge next year.

Tsai Ching-hua, director of the municipal education bureau, said the discovery of the asteroid has set a good model for the city's astronomy education and pledged to study the feasibility of setting up an astronomy theme park in the new Kaohsiung municipality.

Orionid Meteor Shower

Space Weather
Tue, 20 Oct 2009 15:16 EDT

The Orionid meteor shower is underway. Earth is passing through a stream of dusty debris from Halley's Comet, and this is causing meteors to shoot out of the constellation Orion. Earlier today, amateur astronomer Jefferson Teng photographed an Orionid fireball over Shanghai, China.

"I woke up early in the morning to observe the shower through my bedroom window," says Teng. "This one was quite bright considering the light pollution in Shanghai."

Forecasters expect the shower to peak on Wednesday, Oct. 21st, with dozens of meteors per hour. The best time to look is during the dark hours before sunrise. For best results, get away from city lights, but as Teng discovered, country darkness is not absolutely necessary.

Did a meteor make this crater in Latvia?

Associated Press
Mon, 26 Oct 2009 10:07 EDT

Investigators Say Radiation Levels Normal

Scientists were investigating Monday whether a large crater found in a meadow in northern Latvia had been created by meteorite. One expert said it was likely a hoax.

Experts in the Baltic country rushed to the site after reports that a metorite-like object had crashed late Sunday in the Mazsalaca region near the Estonian border.

Uldis Nulle, a scientist at the Latvian Environment, Geology and Meteorology Center, said his first impression after observing the site late Sunday was that the 27-foot (nine-meter) wide and nine foot (three-meter) deep crater had been caused by a meteorite. He said there was smoke coming out of the hole when he arrived.

However, Dainis Ozols, a nature conservationist who examined the hole in daylight on Monday, said it appeared to be a hoax. Ozols said he believes someone dug the hole and tried to make it look like a meteorite crater by burning some pyrotechnic compound at the bottom. He added he would analyze some samples taken from the site.

When asked about Ozols' theory, Nulle refused to comment, saying he needed more time to make tests at the site.

Inga Vetere of the Fire and Rescue Service said they received a call about the alleged meteorite on Sunday evening from an eyewitness. She said a military unit was dispatched to the site and found that radiation levels were normal. There were no injures.

Experts outside Latvia said it would be unusual for such a large meteorite to hit the Earth. The planet is constantly bombarded with objects from outer space, but most burn up in the atmosphere and never reach the surface.

In 2007, a meteorite crashed near Lake Titicaca in Peru, causing a crater about 40 feet (12 meters) wide and 15 feet (five meters) deep.

Asta Pellinen-Wannberg, a meteorite expert at the Swedish Institute of Space Research, said she didn't know the details of the Latvian incident, but that a rock would have to be at least three feet (one meter) in diameter to create a hole that size.

Henning Haack, a lecturer at Copenhagen University's Geological Museum said more information was needed to confirm that the crater was indeed caused by a meteorite.

"With all these kind of reports we get there always is a pretty large margin of error," he said.

Hoax? Video footage of blazing 'meteorite' in Latvia

Daily Mail
Mon, 26 Oct 2009 10:14 EDT

A fiery object struck farmland creating a large crater near a small town in northern Latvia.

No-one was injured in the incident and geologists are now studying the object, which may be a meteorite.

Locals claimed the object fell near a farmhouse on the outskirts of Mazsalaca town in the district of Valmiera last night.

It created a crater which measured 50 feet across and 16 feet deep.

A witness who claimed to have seen the incident described the 'meteorite' as making a noise similar to the one of an aircraft flying at a low altitude.

ldis Nulle, a scientist at the Latvian Environment, Geology and Meteorology Center, said there was smoke coming out of the crater when he arrived at the crash site late Sunday in the Mazsalaca region near the Estonian border.

'My first impression is that, yes, it was a meteorite,' he said. 'All the evidence suggests this when compared to pictures of real meteorite craters.'

He said the rim of the crater was slightly raised and there was a black-grayish scar at the bottom - both signs of a meteorite impact.

Experts outside Latvia said it was unusual for such a large meteorite to hit the Earth. The planet is constantly bombarded with objects from outer space, but most burn up in the atmosphere and never reach the surface.

In 2007, a meteorite crashed near Lake Titicaca in Peru, causing a crater about 40 feet (12 metres) wide and 15 feet (5 metres) deep.

Asta Pellinen-Wannberg, a meteorite expert at the Swedish Institute of Space Research, said she didn't know the details of the Latvian incident, but that a rock would have to be at least three feet (one metre) in diameter to create a hole that size.

Henning Haack, a lecturer at Copenhagen University's Geological Museum said more information was needed to confirm that the crater was indeed caused by a meteorite.

'With all these kind of reports we get there always is a pretty large margin of error,' he said.

In Latvia, Nulle said a group of experts would examine the crater today and bring rock samples back to the capital, Riga, for testing.

Nulle rushed to the site after people in the area reported seeing a fiery object falling from the sky.

Inga Vetere of the Fire and Rescue Service said a military unit has tested the site and found that radiation levels are normal. There were no injures.

She said police have cordoned off the area to prevent souvenir hunters from taking away the soil.

'We are not finally sure that this is a meteorite,' she told Itar-Tass news agency. 'Eyewitnesses said something fell from the sky and fire started.'

Russian blogs posted YouTube video that claimed to show the remains of the meteor burning brightly shortly after the crash, but the validity of the video has not yet been confirmed.

Meteorite falls in northern Latvia, no one injured

RIA Novosti
Mon, 26 Oct 2009 10:59 EDT

No one was injured after a meteorite fell near a small town in northern Latvia on Sunday, local Latvian media reported.

According to media reports, the meteorite fell near a residential house on the outskirts of Mazsalaca town in the Valmiera district of Latvia, leaving a crater of some 20 meters (66 feet) in diameter and 10 meters (33 feet) deep.

A spokesperson for the Latvian State Fire and Rescue Service said that rescuers and soldiers immediately cordoned off the territory, however, it is still not clear whether it was an asteroid or a space satellite.

"The territory has been immediately cordoned off as we still do not know what fell down from the sky. According to preliminary information, it was a meteorite. However, it is possible that it was a [space] satellite or its fragment. A radioactive contamination is also possible," she said.

A witness, who saw the object falling from the sky and leaving a burning trace behind, said it was making a noise similar to the one of an aircraft flying at a low altitude.

On March 2 this year, a 35-meter asteroid came within 72,000 kilometers of Earth. The size of the space rock was comparable to the asteroid that caused the Tunguska disaster, but there was no danger of a collision.

On June 30, 1908, an explosion equivalent to between 5 and 30 megatons of TNT occurred near the Podkamennaya Tunguska River in a remote region of Russia's Siberia.

The Tunguska blast flattened 80 million trees, destroying an area of around 2,150 sq km (830 sq miles).

It is assumed that a huge meteorite had hit the area, although research expeditions failed to find an obvious crater.

Comment: Update: This incident appears to have been staged

'Meteorite' that landed in Latvia is a hoax, experts say

'Meteorite' that landed in Latvia is a hoax, experts say

Tony Halpin
Times Online
Mon, 26 Oct 2009 18:09 EDT

It was the student prank that apparently fell to earth after experts dismissed a meteorite crash in Latvia as an elaborate hoax today.

Dramatic video of a fireball at the bottom of an impact crater on farmland outside the town of Mazsalaca was shown all over the world, taken by a group of film students who said that they had heard the meteor strike.

But experts who examined the scene were less star-struck. Dr Ilgonis Vilks, chairman of the scientific council at the University of Latvia's Institute of Astronomy, said: "It's a fake. It's very disappointing, I was full of hope coming here, but I am certain it is not a meteorite."

Setting aside the astronomical odds of a group of film students happening to be at the ready when a meteorite hits the Earth, Dr Vilks said that several other tell-tale signs had given the game away.

There was green grass inside the crater despite the intense heat supposedly generated by the meteorite. The impact crater, initially reported as 10 metres deep, was actually only 3 metres including a lip of soil a metre high around the hole.

Dr Vilks said that there was neither ejected material from the hole nor any fragments of meteorite on the surrounding land. Finally, there was the flaming "meteorite" itself.

"It's a ball of clay that was burning. We took some samples from it and geologists from the university will examine it," Dr Vilks said. "There was a small blast heard by local people but this was not strong enough to create the crater and there's only a small area in the hole that is burnt."

Dainis Ozols, a nature conservationist who also examined the scene, said that he believed somebody had dug the hole and burnt a pyrotechnic compound at the bottom to make it appear like a meteorite crater.

The alert was first raised on Sunday evening by Ancis Steinbergs, who said that he had been out filming for a university project with his girlfriend and a fellow undergraduate. He was refusing to answer his telephone tonight to answer questions about the experts' assessments.

He had earlier told The Times that the trio had heard a loud roaring sound "like an airplane falling from the sky" seconds before the alleged meteorite hit the field behind some trees.

Mr Steinbergs said: "We saw something burning in the sky like a ball and it was moving very fast and then there was a loud noise. We went to find it and there was this big hole with fire burning in it.

"It was so hot that the camera was misting up. We thought it was really dangerous because there might be an explosion."

Video taken by the group showed them approaching the lip of the crater and filming the glowing hot "meteor" at the bottom as they talked excitedly among themselves. The clip bears similarities in style to the Blair Witch Project, a 1999 film based on supposedly "amateur" footage shot by three missing film students.

Mr Steinbergs said that he called Latvia's Fire and Rescue Service. Inga Vetere, a spokeswoman, said that fire crews had attended the site and cordoned it off. Tests had recorded normal levels of radiation and nobody had been hurt.

Local news agencies reported that the landowner, Larisa Gerasimova, had been quick to capitalise on interest surrounding the crater and had begun to charge curious visitors $2 to view the site.

Earth is bombarded by thousands of small celestial objects every year but most burn up in the atmosphere before they reach the surface. The last recorded meteorite strike on land was in 2007 near Lake Titicaca in Peru, when it left a crater 12 metres wide (40ft) and five metres deep (15ft).

Asteroid blast reveals holes in Earth's defences

David Shiga
New Scientist
Tue, 27 Oct 2009 00:04 EDT

As the US government ponders a strategy to deal with threatening asteroids, a dramatic explosion over Indonesia has underscored how blind we still are to hurtling space rocks.

On 8 October an asteroid detonated high in the atmosphere above South Sulawesi, Indonesia, releasing about as much energy as 50,000 tons of TNT, according to a NASA estimate released on Friday. That's about three times more powerful than the atomic bomb that levelled Hiroshima, making it one of the largest asteroid explosions ever observed.

However, the blast caused no damage on the ground because of the high altitude, 15 to 20 kilometres above Earth's surface, says astronomer Peter Brown of the University of Western Ontario (UWO), Canada.

Brown and Elizabeth Silber, also of UWO, estimated the explosion energy from infrasound waves that rippled halfway around the world and were recorded by an international network of instruments that listens for nuclear explosions.

The explosion was heard by witnesses in Indonesia. Video images of the sky following the event show a dust trail characteristic of an exploding asteroid.

Sudden impact

The amount of energy released suggests the object was about 10 metres across, the researchers say. Such objects are thought to hit Earth about once per decade.

No telescope spotted the asteroid ahead of its impact. That is not surprising, given that only a tiny fraction of asteroids smaller than 100 metres across have been catalogued, says Tim Spahr, director of the Minor Planet Center in Cambridge, Massachusetts. Yet objects as small as 20 or 30 metres across may be capable of doing damage on the ground, he says.

"If you want to find the smallest objects you have to build more, larger telescopes," says Spahr. "A survey that finds all of the 20-metre objects will cost probably multiple billions of dollars."

The White House must develop a policy to address the asteroid hazard by October 2010 under a deadline imposed by Congress. It is likely to be influenced by a report from the National Research Council on the asteroid problem, which is expected by year's end.

September 2009

noreply@blogger.com (Keit) — Sat, 05 Sep 2009 04:45:00 +0000

Meteor Seen Along New Zealand

The Marlborough Express

Mon, 31 Aug 2009 13:00 UTC

A fiery meteor blazed a trail through the skies on Friday morning, with sightings reported from Christchurch to Rotorua.

Zoe Battersby, out for an early walk along Jimmy Amers beach in Kaikoura at around 6.10am, said she couldn't help but notice it.

"It was very bright the size of a streetlight. It looked like it fell into the sea," she said.

Alan Gilmore, resident superintendent of the Canterbury University Mt John Observatory, said meteors entered the atmosphere over New Zealand "several times a year", but he doubted that the rock made it to the ground or water level. "This meteor is very typical, and often they burn up at about 70 kilometres up," he said.

"They are coming into a thicker atmosphere, travelling at 30km a second.

"The friction is strong and they slow up and start to break up.

"It's like throwing a stone at a concrete path."

Mr Gilmore said as meteors broke up, witnesses often saw a bright flash known as a "terminal fireball".

Meteors could be seen from as far as 1000km away and at a height of 100km.

"They are spectacular, often a bright white centre which is the actual rock ... a tiny, brilliant star with a teardrop-shaped glow that's brilliant emerald green caused by the oxygen and the radiation coming off the rock."

Mr Gilmore said a sonic boom often heralded the rare occasion of a meteor landing.

He expected Friday's meteor entered the atmosphere somewhere over the North Island because of the range of reported sightings.

"The impression of closeness is deceptive.

"Because they are bright, people think [the meteorite] landed a couple of paddocks away."

Ireland: Huge 'sky explosion' investigated

BBC News
Fri, 04 Sep 2009 22:19 UTC

An Irish astronomy group is calling for help in tracing the origin of a huge explosion in the skies over the country on Thursday evening.

Astronomy Ireland said it was currently investigating the explosion, which occurred at 2100 BST.

A spokesman said the most likely explanation was a space rock or satellite crashing into the atmosphere.

The group wants anyone who witnessed the event to contact its website at www.astronomy.ie

Astronomy Ireland chairman David Moore said: "So far, reports have been registered by residents in west Cork, Kerry, Cavan and as far north as Donegal, thus suggesting that this spectacular event may have been witnessed by people all over the country.

"In the past two decades there have been two major explosions in the skies over Ireland.

"When we investigated these, we were able to conclude that one was a Russian military satellite that exploded over the country, and the other was a rock from space which we predicted would have fallen on Carlow and this rock was indeed found, becoming the last meteorite fall of the millennium."

Mr Moore said the explosion should not be confused with a hugely-bright star which was positioned just below the full moon on Thursday night.

"This was actually the planet Jupiter and it can be characterised by being by far the brightest star in the entire night sky," he said.

Rain of meteorites makes the moon hum

Rachel Courtland
New Scientist
Tue, 08 Sep 2009 21:38 UTC

The man in the moon is humming a tune, but thankfully the noise won't drown out sensors on future missions peeking at the lunar interior.

A steady barrage of small meteorite impacts should cause the moon to "ring", but no seismometers sent to the moon to date have been sensitive enough to hear it. So Philippe Lognonné at the Institute of Earth Physics of Paris and colleagues decided to work out how loud the ring is.

The team estimated the meteorite population in the solar neighbourhood, and calculated the likely seismic signals that would be created by a range of meteorite sizes and velocities as they strike the moon.

Apollo calibration

To determine how the vibrations from these impacts would be seen by seismometers, the team used data taken by Apollo seismometers four decades ago. These measured the vibrations created by the landings of lunar modules and spent rocket stages.

Since the precise locations and timing of these landings were known, they could be used to gauge how long it would take vibrations caused by meteorite impacts to travel through the moon, and how much the signals might dim.

Their calculations revealed space rocks with masses ranging from a gram to a kilogram do indeed create a hum, but it is subtle. Earth's hum - created by pounding waves - is more than 1000 times louder.

"This shows that all planets may hum, those with and those without atmosphere," says Lognonné.

It's oh so quiet

The moon-hum's quietness means future lunar seismometers should be able to peek deep within the moon without the hum creating problematic background noise, says Lognonné.

Instead seismometers can focus on measuring waves created by moonquakes, tremors created by a variety of sources, including the tidal tug of the Earth. Because seismic waves are sensitive to the type, arrangement and density of rocks they pass through, studying the quakes can reveal more about the moon's interior.

The network of seismometers left by the Apollo missions has been shut down since 1977, so Lognonné hopes more sensitive instruments will be sent to the moon soon. These could reach deeper than the Apollo network to measure the size of the moon's core. "The area within 500 kilometres of the centre of the moon is complete unknown to seismology," Lognonné says.

"I think [the study] is a great idea," says Clive Neal of the University of Notre Dame in Indiana, who was not associated with the research. "Estimating the actual background noise is critical for designing the next generation of seismometers to go to the moon."

The first instrument may be a seismometer proposed for Japan's Selene-2 moon mission, which aims to send a lander to the surface, perhaps as early as 2015.

Journal of Geophysical Research (in press)

Was Vancouver light show a meteor or space junk?

Kimberley Shearon
The Province
Sun, 13 Sep 2009 15:01 UTC

It wasn't a bird and it wasn't a plane. Was it a meteor?

Around 8 p.m. Saturday night a great, big ball of yellowy-white light streaked from east to west across the darkening sky.

Astronomer David Dodge said that the fireball was probably a meteor - basically a rock falling from space.

"It probably wasn't a piece of space junk. The reason why I saw that is that it was going from east to west, and 99.9 per cent of space stuff sent up there is not going east to west."

He said meteors fall to earth every day.

Most burn up before they enter the earth's atmosphere.

Saturday's meteor was notable only because it happened over a populated area Some eye-witnesses, however, had their doubts.

Steve Salsman, was out on his deck when he saw the white ball of light hurtling through the dusky night air.

"It was at about the height of an airplane and had a long red tail," he said.

When the fiery ball appeared to break up, Salsman said he automatically thought that the it might be a dead satellite re-entering the earth's atmosphere.

Another eye-witness, Miles Wishlow, also said he thought the fireball was space junk falling from the sky.

He saw a "shard" break off from the fireball.

"It looked like something man-made that was just way off-course."

The fireball itself, Wishlow said, didn't resemble anything he's seen then past.

"The shape wasn't a perfect circle," he said.

"It was so big and so low compared to the shooting stars and other meteor showers. It was a lot closer than anything I've ever seen."

Dodge said Saturday's meteor might have landed somewhere along Vancouver Island's west coast or in the Pacific Ocean - if it landed at all.

Space-enthusiasts, he said, would be hard-pressed to find a chunk of the meteor, even if it did make it to earth.

"It was something 100 km over its ground path travelling at 70 km per second," he said.

"The human eye has a tough time dealing with that and tends to go for the easy answer. It's not in our neighbour's backyard."

Dodge also pointed out that once a meteor lands on earth it is no more remarkable than a regular old rock.

The biggest difference is that space rocks get to go out in a blaze of glory.

"It was quite breathtaking. Four of us were just standing there watching it," said Wishlow.

Sue Kendall was at her Saturna Island home on the phone with her son in Vancouver when she saw the bright, fast-moving light.

"I said, 'Oh my goodness,' and he looked up and saw it too," she said. "Your brain takes a moment to process it....it was amazing."

Jupiter Captured Comet as Temporary Moon

Nancy Atkinson
Universe Today
Sun, 13 Sep 2009 00:00 UTC

Jupiter's gravity well has been known to capture objects - evidenced by the recent impact on the gas giant discovered by amateur astronomer Anthony Wesley. But one object captured by Jupiter in the mid 1900's was later able to escape from the planet's clutches.

Researchers have found comet 147P/Kushida-Muramatsu was captured as a temporary moon of Jupiter, and remained trapped in an irregular orbit for about twelve years. "Our results demonstrate some of the routes taken by cometary bodies through interplanetary space that can allow them either to enter or to escape situations where they are in orbit around the planet Jupiter," said team member Dr. David Archer.

With this discovery, five such objects have now been discovered where the phenomenon of temporary satellite capture (TSC) has occurred, but this new research suggests it might happen more frequently than was expected. Kushida-Muramatsu orbited Jupiter between 1949 and 1961, the third longest capture period of the five objects.

An international team led by Dr. Katsuhito Ohtsuka modeled the trajectories of 18 "quasi-Hilda comets," objects with the potential to go through a temporary satellite capture by Jupiter that results in them either leaving or joining the "Hilda" group of objects in the asteroid belt. Most of the cases of temporary capture were flybys, where the comets did not complete a full orbit. However, the research team used recent observations tracking Kushida-Muramatsu over nine years to calculate hundreds of possible orbital paths for the comet over the previous century. In all scenarios, Kushida-Muramatsu completed two full revolutions of Jupiter.

"Asteroids and comets can sometimes be distorted or fragmented by tidal effects induced by the gravitational field of a capturing planet, or may even impact with the planet," said Archer, as did comet D/1993 F2 (Shoemaker-Levy 9), which was torn apart on passing close to Jupiter and whose fragments then collided with that planet in 1994. Previous computational studies have shown that Shoemaker-Levy 9 may well have been a quasi-Hilda comet before its capture by Jupiter. The object that impacted with Jupiter this July, causing a new dark spot may also have been a member of this class, even if it did not suffer tidal disruption like Shoemaker-Levy.

"Our work has become very topical again with the discovery this July of an expanding debris plume, created by the dust from the colliding object, which is the evident signature of an impact. The results of our study suggest that impacts on Jupiter and temporary satellite capture events may happen more frequently than we previously expected," said Asher.

The team has also confirmed a future moon of Jupiter. Comet 111P/Helin-Roman-Crockett, which has already orbited Jupiter three times between 1967 and 1985, is due to complete six laps of the giant planet between 2068 and 2086.

"Fortunately for us Jupiter, as the most massive planet with the greatest gravity, sucks objects towards it more readily than other planets and we expect to observe large impacts there more often than on Earth. Comet Kushida-Muramatsu has escaped from the giant planet and will avoid the fate of Shoemaker-Levy 9 for the foreseeable future," said Asher.

The discovery is to be presented at the European Planetary Science Congress in Potsdam.

Catastrophic Darkness

Jeremy Hsu
Astrobiology Magazine
Mon, 14 Sep 2009 04:24 UTC

© Donald E. Davis
This painting depicts an asteroid slamming into tropical, shallow seas of the Yucatan Peninsula in what is today southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 65 million years ago, is believed to have caused the extinction of the dinosaurs and many other species on Earth.

New studies of mixotrophic algae have shown how such organisms could survive the darkened skies that follow a major asteroid impact. Such studies indicate how life manages to survive after a mass extinction event.

A dinosaur-killing asteroid may have wiped out much of life on Earth 65 million years ago, but now scientists have discovered how smaller organisms might have survived in the darkness following such a catastrophic impact.

Survival may have depended upon jack-of-all-trades organisms called mixotrophs that can consume organic matter in the absence of sunlight. That would have proved crucial during the long months of dust and debris blotting out the sun, when plenty of dead or dying organic matter filled the Earth's oceans and lakes.

"Mixotrophs are very good at stabilizing situations by using whatever resources are there, and can often provide what resources there aren't," said Harriet Jones, a biologist at the University of East Anglia in the UK. "They're very good at coping in extreme environments, and enabling other organisms to live."

Jones and her colleagues tested the limits of mixotrophs by subjecting them to six months of low light or complete darkness. The mixotrophs not only thrived, but also surprised researchers by helping sunlight-dependent organisms also survive pitch black conditions.

Simulating catastrophe

Scientists have long debated the overall impact of the K-T extinction that may have heralded the end of the dinosaurs, but most researchers agree that such an event would have thrown up enough dust and debris to darken Earth's skies for about six months. A lack of sunlight would have killed off a majority of plants, eliminating the food supply for animals higher up the food chain.

Many scientists assumed that even smaller organisms would struggle just to stay alive during months of almost complete darkness. Some previous studies even looked at how some organisms such as mixotrophs can survive low light and low food conditions. But no one had tried to test how well mixotrophs would survive the catastrophic environment following something such as the K-T event, Jones said.

"The literature was always saying in that biological production would cease in a post-catastrophic environment," Jones noted. "We felt that because of what mixotrophy algae could do, that wasn't always the case."

Jones joined forces with Charles Cockell, a microbiologist at the Open University based in the UK who specializes in catastrophic environments, as well as other researchers. They tested both freshwater and ocean mixotrophs under conditions ranging from low light to complete darkness for six months, and added food sources during short-term experiments to simulate decaying organic matter.

However, Jones and her colleagues also wanted to see how mixotrophs fared when living together with phototrophs, or light-dependent organisms. They tested mixotrophs and phototrophs separately and together under the different light conditions.

Live together or die alone

Turns out that the mixotrophs survived all the experiments, and some even grew under the low light conditions. Their ability to consume other organisms or organic matter helped them rebound quickly after low light returned, perhaps similar to the clouds of dust and debris finally beginning to clear.

But the real shock came from how well light-dependent organisms did when living with the mixotrophs. No photosynthesis could take place under the complete darkness, but the phototrophs mostly managed to survive based on nutrients cycled by the active mixotrophs.

"We were extremely surprised at how well phototrophs did during six months darkness, when they can't eat at all," Jones said. Such findings may cause researchers to rethink how well certain life forms survived the catastrophic impacts that dot Earth's geological record.

Furthermore, the mixotroph activity allowed the phototroph populations to rebound quickly back to normal within a month. And in the end, both mixotrophs and phototrophs tended to fare better when living together.

"So long as mixotrophs are cycling nutrients, [phototroph] algae can take off quickly and get the life cycle going," Jones explained.

Life lessons for survival

Only one low light condition saw phototrophs fail to survive while living with mixotrophs. The phototrophs may have used too much energy trying to do photosynthesis in the weak light, or perhaps the hungry mixotrophs simply fed on their fellow organisms.

"You can only do so much in a flask, and obviously the mix of species would be much greater in a natural environment," Jones pointed out.

Still, the overall results suggest how mixotrophs provide a cushion against catastrophe for certain ecosystems, and may even prevent huge population crashes. The research is further detailed in the July/August issue of the journal Astrobiology.

Jones and her colleagues plan to conduct more studies with greater mixes of species, in an environment that would more closely resemble the natural world. They also want to shorten experiments to three months rather than six.

That looks all well and good for the smaller organisms. But humans, who would have a much harder time feeding themselves if the skies went dark, may want to plan on how to prevent such catastrophic asteroid impacts in the future.

Mini-Comets Within a Comet Lit Up 17P/Holmes During Megaoutburst

PhysOrg
Wed, 16 Sep 2009 13:41 UTC

Astronomers from the University of California, Los Angeles and the University of Hawaii have discovered multiple fragments ejected during the largest cometary outburst ever witnessed. Images and animations showing fragments rapidly flying away from the nucleus of comet 17P/Holmes will be presented by Rachel Stevenson at the European Planetary Science Congress in Potsdam, Germany, on Wednesday 16 September.

Stevenson, together with colleagues Jan Kleyna and David Jewitt, began observing comet Holmes in October 2007 soon after it was reported that the small (3.6 km wide) body had brightened by a million times in less than a day. They continued observing for several weeks after the outburst using the Canada- France- Hawaii Telescope in Hawaii and watched as the dust cloud ejected by the comet grew to be larger than the Sun.

The astronomers examined a sequence of images taken over nine nights in November 2007 using a digital filter that enhances sharp discontinuities within images. The filter, called a Laplacian filter, is particularly good at picking out faint small-scale features that would otherwise remain undetected against the bright background of the expanding comet. They found numerous small objects that moved radially away from the nucleus at speeds up to 125 metres per second (280 mph). These objects were too bright to simply be bare rocks, but instead were more like mini-comets creating their own dust clouds as the ice sublimated from their surfaces.

"Initially we thought this comet was unique simply because of the scale of the outburst," said Stevenson. "But we soon realized that the aftermath of the outburst showed unusual features, such as these fast-moving fragments, that have not been detected around other comets."

© Jewitt, Stevenson, Kleyna
Image of comet Holmes from the 3.6-meter Canada-France-Hawaii telescope on Mauna Kea showing the large expanding dust coma. On the left, a 'raw' image is shown, in which the brightness reflects the distribution of dust in the coma of the comet (the nucleus is in the bright, point-like region to the upper left of center). On the right is shown the same image after application of the Laplacian spatial filter, to emphasize fine structures. The white/black circular objects are background stars enhanced by the Laplacian filter.

While cometary outbursts are common, their causes are unknown. One possibility is that internal pressure built up as the comet moved closer to the Sun and sub-surface ices evaporated.

The pressure eventually became too great and part of the surface broke away, releasing a huge cloud of dust and gas, as well as larger fragments.

Surprisingly, the solid nucleus of comet Holmes survived the outburst and continued on its orbit, seemingly unperturbed. Holmes takes approximately 6 years to circle the Sun, and travels between the inner edge of the asteroid belt to beyond Jupiter. The comet is now moving away from the Sun but will return to its closest approach to the Sun in 2014, when astronomers will examine it for signs of further outbursts.

Rare Meteorite Found by 'Fireball' Observatory

Hazel Muir
New Scientist
Thu, 17 Sep 2009 23:36 UTC

© Desert Fireball Network, funding from STFC and the EU
This all-sky image was taken by the Desert Fireball Network in Western Australia with a fish-eye lens. The film is exposed for most of the night, so stars trace long curves; the white streak diagonally across them is a firebal

A rare meteorite that may have been born in Earth's neighbourhood has been found using a new 'fireball' observatory in Australia.

Scientists can learn how the solar system formed by studying meteorites that originated in different places within it. The trouble is, they don't know where the vast majority of meteorites actually came from.
"Trying to interpret what happened in the early solar system without knowing where meteorites are from is like trying to interpret the geology of Britain from random rocks dumped in your back yard," says Phil Bland at Imperial College London.

To remedy that, Bland's team set up the Desert Fireball Network in Western Australia's Nullarbor Desert in 2006. This trial network, currently with four robotic cameras spread over roughly 250,000 square kilometres, exposes photographic film to clear skies throughout the night.

If the cameras record a bright meteor, or fireball, as a rock falls through Earth's atmosphere, scientists can calculate its trajectory by triangulation, estimate the rock's likely landing site, then look for it.

Small parent

Following the network's first observation of a fireball on 20 July 2007, search parties found three fragments of the resulting meteorite, named Bunburra Rockhole, in 2008 and 2009.

The meteorite is made of basalt, the most common type of solidified lava on Earth. Scientists typically assume that basaltic meteorites are chips off the giant asteroid.

But Vesta is so large - roughly 530 kilometres across - that gravity caused its component materials to settle into different layers soon after its formation. The compounds in this meteorite, by contrast, are better mixed, suggesting it came from a smaller asteroid a few tens of kilometres wide.

Molten rock

Orbital calculations suggest this parent asteroid orbited in the innermost side of the asteroid belt between Mars and Jupiter until a collision chipped Bunburra Rockhole off the asteroid around 10 or 20 million years ago.

But though its parent body once orbited inside the asteroid belt, it may have been born closer to the sun. A theory proposed in 2006 argues that molten rock swirled around the young sun only in the current region of Venus, Earth and Mars, with many molten blobs subsequently flung out to the innermost asteroid belt.

In that case, Bunburra Rockhole could represent the type of material that clumped together to build Earth. "Our big question is - what were the building blocks for the terrestrial planets?" says Bland. "This rock gets us a little bit closer to that."

Journal reference: Science (DOI: 10.1126/science.1174787)

Astronomical Birth Event Results in a Multitude of 'Baby' Comets

Helen Altonn
Honolulu Star Bulletin
Thu, 17 Sep 2009 01:03 UTC

Astronomers who were dazzled by the 2007 explosion of a comet into the largest object in the solar system have discovered it gave birth to a bunch of baby comets.

Reporting the "largest comet birth ever seen" were David Jewitt, Rachel Stevenson and Jan Kleyna, who observed the event through a Mauna Kea telescope.

Jewitt, a professor, and Stevenson, his graduate student, left the University of Hawaii Institute for Astronomy this summer to join the University of California, Los Angeles. Kleyna is an astrobiology postdoctoral researcher at the institute.

They and others on an institute team observed the spectacular outburst of Comet 17P/Holmes in October and November 2007 from the Canada-France-Hawaii Telescope on Mauna Kea.

The normally obscure comet burst from a tiny nucleus of ice and rock into an object larger than the sun. The astronomers measured the mass of ejected dust at 900,000 miles across. The diameter of the sun, by comparison, is 865,000 miles.

"It was quite an event," Kleyna said in an interview yesterday. "We got some very high-quality data with a very large camera on the CFH Telescope."

He said the astronomers digitally enhanced the images and "over several nights found these bright spots" flying away from the nucleus of the comet at speeds of up to 280 mph.

"We concluded these probably were pieces of icy substance expelled from Comet Holmes like mini-comets," he said.

If they were solid chunks of ice they would have been invisible but they were bright with activity, creating their own dust clouds as surface ice vaporized and transformed into gas, Kleyna said.

"There have been some fragmented comets," Kleyna said, "but I don't think we've seen an eruption that generated many comets before."

"Initially, we thought this comet was unique simply because of the scale of the outburst," Stevenson said in a statement. "But we soon realized that the aftermath of the outburst showed unusual features, such as these fast-moving fragments that have not been detected around other comets."

The team continued observing for several weeks. Jewitt, in a Star-Bulletin interview in 2007, said the comet was expanding at about 1,100 mph and was "an unprecedented million times brighter" than before.

What the astronomers saw was "just awesome," Jewitt said, and "very, very weird. An outburst by a factor of a million is staggering, and I don't know of a previous case like this," he said as he and his team studied the expanding comet.

Sightings of the baby comets were reported at the European Planetary Science Congress this week in Potsdam, Germany.

Comet Holmes was discovered in an outburst in November 1892, then again in January 1893, probably when the comet was at its closest to the sun, Jewitt said in 2007.

It takes Comet Holmes about six years to circle the sun, traveling between the inner edge of the asteroid belt to beyond Jupiter. Its next closest approach to the sun will be in 2014.

Kleyna said the astronomers are still analyzing data from the 2007 observations. "There are other interesting details of the comet we're looking at."

What Do Dinosaurs And The Maya Have In Common?

Science Daily
Mon, 21 Sep 2009 07:01 EDT

One of the world's most famous asteroid craters, the Chicxulub crater, has been the subject of research for about twenty years. The asteroid impact that formed it probably put an end to the dinosaurs and helped mammals to flourish.

Together with an Anglo-American team, an ETH Zurich researcher has studied the most recent deposits that filled the crater. The results provide accurate dating of the limestones and a valuable basis for archaeologists to research the Maya.

The discovery of the Chicxulub asteroid crater was detective work: in 1980, based on iridium anomalies in clay sediments - which could only be formed extraterrestrially - the American physicist Walter Alvarez postulated a devastating asteroid impact at the transition from the Cretaceous to the Paleogene around 65 million years ago.

Another ten years passed before the associated crater was discovered on the Yucatan peninsula. Research work since then has focused mainly on the structure of the crater, which has been buried in a layer of sediment up to two kilometres thick since its formation and which can only be studied using boreholes or geophysical methods.

Little is known about the sediments close to the surface. Most of the geological maps also originate from the time before the Chicxulub crater was discovered, and do not completely reflect the geology.

Crater ring as a geological boundary

© Geological Survey of Canada
Chicxulub crater gravity map - white dots represent the locations of water-filled sinkholes

Together with American and English researchers, Adrian Gilli, Senior Lecturer at the Geological Institute of ETH Zurich, has now filled in a few of the gaps in the knowledge about the near-surface rock deposits. Gilli says, "The crater ring of the Chicxulub crater is scarcely recognisable in the terrain." This is despite the fact that it is distinctly different, geo-morphologically speaking, from the crater interior: the ring, which is about five kilometres wide and has a radius of approximately 90 kilometres around the port of Chicxulub, is criss-crossed by fractures that also occur frequently outside the crater ring.

The limestone along these faults has been riddled with holes and eroded by rain and groundwater. A process known as karstification has to date created about 3000 circular collapses forming small basins filled with groundwater. The Maya called these basins "d'zonot", or "cenotes", regarding them as a direct connection to the underworld and using such places as sacrificial sites.

Crater sediments distinctly younger

Previously, the rocks outside the crater ring were suspected to be older than those inside, but now researchers have for the first time been able to determine their precise age using a method based on the isotope ratios of strontium 87 to strontium 86 in the limestone, thus confirming their suspicions.

The rock samples inside the ring gave an age of between 2.3 and 6 million years. On the other hand, the rocks outside the ring showed more variable strontium isotope ratios and are from 10 to 33 million years old. Gilli suspects that the crater basin had been covered by seawater for a prolonged time, which allowed the more recent sediments to be deposited there.

The results help to understand the geology better and to re-draw and refine the outdated maps. Archaeology research can also benefit from the geologists' work: for example, the life of the Maya, whose important settlements Mayapán and Chichén Itzá are located in these two geologically different regions, can be better researched on the basis of the strontium data.

Gilli explains, "We really wanted to carry out a purely geo-archaeological study in which, initially, the crater played no part at all." The aim was to refine an earlier strontium isotopes study of the rocks around the former Maya sites by adding 72 new samples to enable the identification of small-scale variations in the isotope ratio. This is because the transitions between regions with a different ratio of strontium 87 to strontium 86 can be particularly important: Gilli says, enthusiastically, "We can obtain a very large amount of information about the lifestyle of the people from settlements at such boundaries, such as the Maya city of Mayapán."

Geology and archaeology complement each other

© Geological Survey of Canada
Shocked quartz grains produced by the impact (intracrater breccia sample Y6 N14 of the Chicxulub crater)

For instance, the fine-mesh geological measurement network in conjunction with the biological strontium isotope values makes migration movements visible. It could yield knowledge about where the Maya obtained their building materials or where they cultivated their maize.

This is because the weathering of rocks carries strontium into the soil and from there into plants. When eaten by humans or animals in food, strontium instead of calcium is incorporated into teeth when they are formed in childhood. If detailed strontium isotopes maps are available, this enables the region in which a person grew up to be determined. Gilli says, "It gets particularly exciting if the origin of the rulers of the various Maya towns can be determined. This in turn allows conclusions to be drawn about the social structures of the Maya."

The scientist is convinced that the geological analyses of the strontium isotope ratios form an important basis for the work of the archaeologists, who are working ever more frequently with the biological strontium isotopes from bones or teeth.

Chicxulub asteroid crater

The asteroid with a diameter of about ten kilometres that created the Chicxulub crater most probably caused the worldwide extinction of species at the boundary between the Cretaceous and the Palaeogene. The event caused the extinction of about 75 percent of all species.

Its effect was due mainly to the fact that it impacted into rocks rich in carbonate and anhydrite. This hurled massive amounts of carbon dioxide (CO2) and sulphur dioxide (SO2) into the atmosphere. It is estimated that between 200 and 3000 cubic kilometres of sediments vaporised, releasing 35 to 700 million tons of sulphur and 10 billion tons of CO2 into the atmosphere.

The ozone layer would probably have been destroyed within a very short time, and there must have been complete darkness over the Earth for months due to the dust in the atmosphere. This had serious short- and long-term consequences for the climate and biosphere. The crater that remains has a diameter of 180 kilometres and extends from the Yucatán peninsula to the Gulf of Mexico.

Maya

The first evidence of the Maya in Central America can be traced back to 3000 B.C. Over the course of history, their cultural centres moved from the uplands to the lowlands and finally to the north of the Yucatán. Chichén Itzá in the north-west of the Yucatán peninsula flourished during the classical period, whereas Mayapán was the last Maya capital in the north of the peninsula.

When the Spanish arrived in the late 15th century, the centres of post-classical Maya culture were in the extreme north of the Yucatán, while the central lowlands remained only thinly populated. Today, around 6.1 million Maya still live on the Yucatán peninsula and in Belize, Guatemala and Honduras.

Gilli A. et al.: Geological and archaeological implications of strontium isotope analysis of exposed bedrock in the Chicxulub crater basin, northwestern Yucatán, Mexico. Geology (2009), 37, 723-726, doi:10.1130/G30098A.1

Sept. 25, 2002: Mysterious Meteorite Dazzles Siberia

Randy Alfred
Wired
Fri, 25 Sep 2009 09:47 EDT

2002: A large fireball flashes across the night skies of the Irkutsk region of Siberia. What may have been a comet causes electrical circuits to come alive and leaves residents worrying about radioactivity.

Eyewitnesses saw the sky light up. More than a hundred people in the sparsely settled area reported seeing it.

At least one person fell to the floor in horror, believing that some religious doomsday had arrived. Others were sure that nuclear war had broken out.

The region was in an accustomed power blackout that night. But even as the meteor's visible energy lit up the skies outside, its strong electrical field activated the power grid. Residents reported that the lamps in their homes turned on for a few seconds.

People who were outside heard a buzzing, crackling sound in the air. The tops of fence posts lit up with electrical discharges.

The impact shattered windows for a dozen miles around and was felt up to 60 miles away. Scientists in Irkutsk recorded "seismic waves comparable to a middle-power earthquake."

Early reports indicated that local people may have suffered mild radiation poisoning, symptomized by aching joints, kidney problems and high blood pressure.

Hunters who first explored the area near the presumed impact reported an area of downed trees surrounded by charred forest.

The Institute of Solar and Earth Physics of the Siberian division of the Russian Academy of Sciences wanted to investigate, but was hampered by a lack of funds and the remoteness of the area. It was May 2003 before a scientific expedition could reach the hilly forests of Bodaibo, northeast of Irkutsk, and Lake Baikal.

Scientists found about 40 square miles of trees smashed in the pattern associated with big explosions. The meteorite had broken up before hitting the ground and left a score of craters, up to 65 feet in diameter. Nearby tree stumps were shattered or burned.

A U.S. spy satellite that had picked up the blazing ball at about 40 miles altitude lost it a little below 20 miles: It's possible that's where the ball exploded.

U.S. military analysts estimated the explosion as equivalent to 0.2 to 0.5 kilotons, though Russian physicist Andrey Olkhovatov placed it much higher at 4 to 5 kilotons.

No large fragments were found, only tiny hollow spheres, generally less than 0.1 to 0.2 millimeters diameter. The brown and dark-brown particles contained oxide and silicate minerals typical of meteorites, along with pyrite with nickel content, and various iron compounds. None of these is typical of the local geology.

Some sources say gamma radiation was at background level, but others say local water samples showed high levels of tritium, along with radioactive isotopes of cobalt and cesium.

Whether the fireball was rock that pulverized or, as some Soviet scientists concluded, an icy comet, there's this scary fact to consider: It was not picked up in advance by any existing warning systems. If the fireball had exploded on or over a major city, it could have killed tens of thousands of people.

Flashback: Siberia meteorite flattens 40 sq miles

Robin Shepherd
Times Online
Sat, 07 Jun 2003 14:30 EDT

If it had hit Central London, Britain would no longer have a capital city. The force of the meteorite that hit eastern Siberia last September destroyed 40 square miles of forest and caused earth tremors felt 60 miles away.

An expedition from Russia's Kosmopoisk institute has only recently reached the site in a remote area north of Lake Baikal because of bad weather and difficult terrain, the Interfax news agency said yesterday.

Fragments of the meteorite had apparently exploded into shrapnel 18 miles above the Earth with the force of at least 200 tonnes of TNT.

At the time, Russian media reported that villagers 60 miles away had witnessed a gigantic fireball screeching down from the sky, causing windows to rattle and house lights to swing as they were hit by blast waves on September 25. There were no reported casualties.

Flashback: 200 Tons of TNT Falls on Taiga

FarShores News
Sun, 03 Aug 2003 14:31 EDT

According to Yekaterina Shestakova, a town hall official, the expedition consists of five people, three scientists from the Moscow Meteorite Committee and two from Irkutsk. The expedition will go down the Vitim river from Bodaibo to the village of Vitimsky, from where it will proceed on foot to the place where the mysterious celestial body is presumed to have fallen.

It will be recalled that a large bolide entered the atmosphere over the villages of Vitimsky and Mama, in the Mama-Chuya district, on the night of September 24-25, 2002, at an angle of 32 degrees over the horizon and an altitude of 60 kilometers. Then there was a flash at 30 kilometers above the earth's surface which was registered by Americans. According to the U.S. military, the explosion occurred at 58o 13.6, s.l. and 113o 27.6, e.lat.

A team from Yekaterinburg is already working in the area: Twelve scientists and undergraduates are exploring the area where the U.S. satellite registered a second point of the bolides path at an altitude of 30 kilometers, canvassing eyewitnesses and finding numerous traces of the bolide.

By the end of July yet another team of Irkutsk scientists, led by Sergei Yazev, director of the Irkutsk University Astronomic Laboratory, will arrive at the Mama-Chuya district. "All four expeditions will be working independently," Sergei Yazev said.

"We want to study different sections of the bolides flight path." The scientists are especially interested in the virtually unexplored area - from the point where the bolide was registered by the U.S. satellite (30 kilometers over the earths surface) and the place where it presumably fell to the ground. Scientists believe that this area is 30 kilometers to 50 kilometers northeast of that point.

Samples of the snow taken in the area of the meteorites fall were found to contain remnants of meteorite substance - particles of iron, nickel, and chrome that are usually present in meteorites. Furthermore, particles of enstatite, nifeline, and cristobalite were discovered. The last mentioned element is a modification of ordinary quartz that has been subjected to high temperature impact. This rarely happens on earth. In addition, cristobalite and nifeline virtually never occur together. "It seems that a fairly large bolide exploded in the atmosphere," Sergei Yazev says. "It had a 200-ton TNT equivalent. There is nothing to suggest that the body that blew up was man-made - no trace of rocket fuel or increased radiation level or elements of metal structures. Apparently it was a stone or iron-and-stone bolide. Its dimensions have yet to be established."

According to eyewitness accounts, a huge star left a shining curve in the sky, falling somewhere in the cone-shaped hills. The dazzling flash lit up the taiga for a few seconds, as though bathing it in electric light, whereupon came an explosion, so powerful that windows were shattered in houses for dozens of kilometers around. Meteorites are usually given the name of the nearest populated area. It so happens that in 1902, a Bodaibo meteorite was found in the same area. The Sikhote-Alin meteorite fell in 1947. The Chulym bolide dropped on Siberia in February 1986.

The bolide flights were accompanied by a strong induction effect, with household electric bulbs and electronic equipment burning out. Presumably, similar phenomena occurred prior to the fall of the Tunguska meteorite. The moment the Vitim body fell, Georgy Kaurtsev, a Mama airport security officer, ran out into the street: "When the sound of the explosion came, a bulb went on although the switch was in the off position. I put on a jacket and rushed out. There is a meteorological station near the building. It is fenced off with wire mounted on 12 wooden poles. I saw balls of light, 20 to 30 centimeters in diameter, shining atop every one of them. Before long, they went out, but there was no trace left on the poles in the morning."

Maybe the scientists will find the place where the meteorite fell, and study it. Scientists believe it is critical to learn more about the nature of these "space aliens" in expectation of a more serious meteorite strike.

Source: Moscow News

Scientists See Water Ice In Fresh Meteorite Craters On Mars

ScienceDaily
Fri, 25 Sep 2009 01:08 EDT

© NASA/JPL-Caltech/University of Arizona
Earlier and later HiRISE images of a fresh meteorite crater 12 meters, or 40 feet, across located within Arcadia Planitia on Mars show how water ice excavated at the crater faded with time. The images, each 35 meters, or 115 feet across, were taken in November 2008 and January 2009.

NASA's Mars Reconnaissance Orbiter has revealed frozen water hiding just below the surface of mid-latitude Mars. The spacecraft's observations were obtained from orbit after meteorites excavated fresh craters on the Red Planet.

Scientists controlling instruments on the orbiter found bright ice exposed at five Martian sites with new craters that range in depth from approximately half a meter to 2.5 meters (1.5 feet to 8 feet). The craters did not exist in earlier images of the same sites. Some of the craters show a thin layer of bright ice atop darker underlying material. The bright patches darkened in the weeks following initial observations, as the freshly exposed ice vaporized into the thin Martian atmosphere. One of the new craters had a bright patch of material large enough for one of the orbiter's instruments to confirm it is water-ice.

The finds indicate water-ice occurs beneath Mars' surface halfway between the north pole and the equator, a lower latitude than expected in the Martian climate.

"This ice is a relic of a more humid climate from perhaps just several thousand years ago," said Shane Byrne of the University of Arizona, Tucson.

Byrne is a member of the team operating the orbiter's High Resolution Imaging Science Experiment, or HiRISE camera, which captured the unprecedented images. Byrne and 17 co-authors report the findings in the Sept. 25 edition of the journal Science.

"We now know we can use new impact sites as probes to look for ice in the shallow subsurface," said Megan Kennedy of Malin Space Science Systems in San Diego, a co-author of the paper and member of the team operating the orbiter's Context Camera.

During a typical week, the Context Camera returns more than 200 images of Mars that cover a total area greater than California. The camera team examines each image, sometimes finding dark spots that fresh, small craters make in terrain covered with dust. Checking earlier photos of the same areas can confirm a feature is new. The team has found more than 100 fresh impact sites, mostly closer to the equator than the ones that revealed ice.

An image from the camera on Aug. 10, 2008, showed apparent cratering that occurred after an image of the same ground was taken 67 days earlier. The opportunity to study such a fresh impact site prompted a look by the orbiter's higher resolution camera on Sept. 12, 2009, confirming a cluster of small craters.

"Something unusual jumped out," Byrne said. "We observed bright material at the bottoms of the craters with a very distinct color. It looked a lot like ice."

The bright material at that site did not cover enough area for a spectrometer instrument on the orbiter to determine its composition. However, a Sept. 18, 2008, image of a different mid-latitude site showed a crater that had not existed eight months earlier. This crater had a larger area of bright material.

"We were excited about it, so we did a quick-turnaround observation," said co-author Kim Seelos of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Everyone thought it was water-ice, but it was important to get the spectrum for confirmation."

Mars Reconnaissance Orbiter Project Scientist Rich Zurek, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., said, "This mission is designed to facilitate coordination and quick response by the science teams. That makes it possible to detect and understand rapidly changing features."

The ice exposed by fresh impacts suggests that NASA's Viking Lander 2, digging into mid-latitude Mars in 1976, might have struck ice if it had dug 10 centimeters (4 inches) deeper. The Viking 2 mission, which consisted of an orbiter and a lander, launched in September 1975 and became one of the first two space probes to land successfully on the Martian surface. The Viking 1 and 2 landers characterized the structure and composition of the atmosphere and surface. They also conducted on-the-spot biological tests for life on another planet.

Asteroid attack: Putting Earth's defences to the test

David Shiga
New Scientist
Thu, 24 Sep 2009 11:46 EDT

It looks inconsequential enough, the faint little spot moving leisurely across the sky. The mountain-top telescope that just detected it is taking it very seriously, though. It is an asteroid, one never seen before. Rapid-survey telescopes discover thousands of asteroids every year, but there's something very particular about this one. The telescope's software decides to wake several human astronomers with a text message they hoped they would never receive. The asteroid is on a collision course with Earth. It is the size of a skyscraper and it's big enough to raze a city to the ground. Oh, and it will be here in three days.

Far-fetched it might seem, but this scenario is all too plausible. Certainly it is realistic enough that the US air force recently brought together scientists, military officers and emergency-response officials for the first time to assess the nation's ability to cope, should it come to pass.

They were asked to imagine how their respective organisations would respond to a mythical asteroid called Innoculatus striking the Earth after just three days' warning. The asteroid consisted of two parts: a pile of rubble 270 metres across which was destined to splash down in the Atlantic Ocean off the west coast of Africa, and a 50-metre-wide rock heading, in true Hollywood style, directly for Washington DC.

The exercise, which took place in December 2008, exposed the chilling dangers asteroids pose. Not only is there no plan for what to do when an asteroid hits, but our early-warning systems - which could make the difference between life and death - are woefully inadequate. The meeting provided just the wake-up call organiser Peter Garreston had hoped to create. He has long been concerned about the threat of an impact. "As a taxpayer, I would appreciate my air force taking a look at something that would be certainly as bad as nuclear terrorism in a city, and potentially a civilisation-ending event," he says.

The latest space rock to put the frighteners on us was 2008 TC3. This car-sized object exploded in the atmosphere over Sudan in October last year. A telescope first spotted it just 20 hours before impact - at a distance of 500,000 kilometres - and astronomers say we were lucky to get any warning at all.

Thankfully, 2008 TC3 was far too small to do any damage on the ground, but we are nearly as blind to objects big enough to do serious harm. We have barely begun to track down the millions of skyscraper-sized asteroids zipping around Earth's neighbourhood, any one of which could unleash as much destructive power as a nuclear bomb on impact.

Asteroid impacts are not as rare as you might think. It is widely accepted that an asteroid or comet 30 to 50 metres across exploded over Tunguska in Siberia in 1908, flattening trees for dozens of kilometres all around. The chance of a similar impact is about 1 in 500 each year (Nature, vol 453, p 1178). Put another way, that's a 10 per cent chance of an impact in the next 50 years (see Should we panic?).

"Fifty-metre asteroids scare me to death," says Timothy Spahr, director of the Minor Planet Center in Cambridge, Massachusetts. "I could easily see a 50-metre object hitting in three days causing absolute pandemonium."

During the US air force planning exercise, the participating scientists explained that with so little warning there would be no hope of preventing an impact. Even Innoculatus's smaller 50-metre asteroid would weigh hundreds of thousands of tonnes, requiring an enormous push to change its trajectory appreciably - so much so that detonating a nuke near it in space would not provide a sufficient impulse so late in the game to cause a miss. To deflect an asteroid sufficiently, force would need to be applied years in advance (see Could we nuke it?).

In fact, it could make things worse by breaking the asteroid into pieces, some of which could be large enough to do damage, and even create a blizzard of meteors that would destroy satellites in Earth orbit.

Panic on the streets

Realistically, though, the nuclear option would not be on the table in the first place: the nuclear-tipped missiles sitting patiently in silos around the world are not designed to track and home in on an asteroid or even survive for more than a few minutes in space. Instead, we would simply have to brace ourselves for the impact.

The good news is that even a little warning makes a big difference, simply because it would allow us to predict the time and location of impact. In the case of 2008 TC3, just a few hours after the asteroid's discovery, NASA scientists completed calculations that predicted an atmospheric plunge over an unpopulated desert area of northern Sudan, with timing accurate to within a minute.

But participants in the planning exercise worried that if an asteroid posing an imminent threat to a populated area were discovered, and the situation were not handled properly, panic and lack of coordination could lead to chaos on the roads.

Spahr was not involved in the exercise, but shares those concerns. "With a three-day warning, you can walk away and be safe. But it scares me, given how poorly we've handled things of this nature in the past," he says, citing the failure to fully evacuate New Orleans ahead of hurricane Katrina in 2005. "I'm picturing people panicking and driving the wrong way on the freeway, screaming 'Oh my god, it's going to kill us!'"

To prevent panic and disorganised movement, it is crucial for authorities to develop an evacuation plan and communicate it to the public as soon as possible after discovery of the dangerous object, since such discoveries are posted automatically online and would cause a media firestorm.

Such measures should ensure the streets would be very quiet as an object such as Innoculatus plunges into the atmosphere and makes its final approach to Washington DC. The compression of the atmosphere in front of the asteroid and friction with the air would cause rapid heating. At lower altitudes, where the air is denser, the heating becomes so intense that the asteroid vaporises and explodes. For the Tunguska event, this happened at about 8 kilometres above ground.

Supersonic shock wave

If you were unfortunate enough to be looking up from directly below, the explosion would be brighter than the sun. The visible and infrared radiation would be strong enough to make anything flammable ignite, says Mark Boslough of Sandia National Laboratory in Livermore, California. "It's like being in a broiler oven," he says. Anyone directly exposed would quickly be very badly burned.

Even before the sound of the blast reaches you, your body would be smashed by a devastating supersonic shock wave as the explosion creates a bubble of high-pressure air that expands faster than the speed of sound. Planetary scientist Jay Melosh of Purdue University in New York once experienced a shock wave from an experiment that exploded 500 tonnes of TNT, a tiny blast in comparison with the blast from an asteroid. "I was standing on top of a hill about 1.5 kilometres away wearing earplugs," he recalls. Melosh says you would see the shockwave in the air due to the way it refracts light. "It's a shimmering bubble," he says. "It spreads out in complete silence until it reaches you, then you hear a double boom."

Melosh was at a safe distance, but at ground zero below an exploding asteroid, the shock wave would be powerful enough to knock down buildings. It would arrive about 30 seconds after the blazing hot flash of light, and could also knock any nearby planes out of the sky, Boslough says. Any surviving buildings would be pummelled by raging winds blowing faster than any hurricane can muster.

Of course, two-thirds of Earth's surface is ocean. While our atmosphere is likely to protect us from asteroids smaller than 100 metres across, anything larger hitting the ocean - including chunks of Innoculatus's rubble pile - would cause a giant splash that could smash coastal buildings with high-speed volleys of water. The tremendous damage and loss of life that would ensue if multiple cities around an ocean basin were flooded led NASA scientists in 2003 to rate ocean impacts by asteroids as far more dangerous than those on or over land.

Recent computer simulations offer some hope, though. They suggest that the monster waves generated by ocean impacts would typically break far from shore, dissipating most of their energy before they could reach cities - unless the impact was very close to the coast, of course. Another ray of hope is that 100-metre asteroids hit Earth only about one-tenth as often as 30-metre objects.

Lasting just one day, the 2008 US air force exercise could barely scratch the surface of the incoming-asteroid problem. Not surprisingly, it discovered that should the nightmare come true, there is no plan for how to coordinate the activities of NASA, emergency planners, the US military and other parts of government. Further planning exercises are needed: the time saved through early preparation will be crucial if an evacuation is ever required at short notice.

Our chance of having any prior warning at all for an approaching 30-metre asteroid is no better than 25 to 35 per cent with existing sky surveillance, calculates astronomer Alan Harris of the Space Science Institute in Boulder, Colorado. The sun washes out half of the sky with daylight, blinding us to 50 per cent of threatening objects. Even glare from the moon can hide unwelcome incoming guests.

What's more, two of the world's three leading asteroid surveys are based in Arizona, including the Catalina Sky Survey, which discovered 2008 TC3. The region tends to cloud over between July and September. "Shift 2008 TC3 back to July and forget it. It wouldn't have been seen," says Spahr.

Now picture this ugly scenario, which worried some participants in the air force exercise: an asteroid flies out of nowhere and explodes over a sensitive nuclear-armed region, like South-East Asia or the Middle East. There's a reasonable chance that such an airburst could be misinterpreted as a nuclear attack. Both produce a bright flash, a blast wave and raging winds.

Such concerns were one reason why, when NASA found 2008 TC3 in its sights, it not only issued a press release but also alerted the US State Department, military commanders, and White House officials, says Lindley Johnson at NASA headquarters, who oversees the agency's work on near-Earth objects. "If it had been going down in the middle of the Pacific somewhere, we probably would not have worried too much more about it, but since it was [going to be] on land and near the Middle East, we did our full alerting," he says.

There is one major way to improve our prospects - point more eyes at the skies. The European Space Agency wants to get into the monitoring game and may set its telescopes at the European Southern Observatory in Chile on the problem. This could fill a gap in the NASA-funded surveys, which are limited to watching the skies of the northern hemisphere, says Richard Crowther of the UK's Science and Technology Facilities Council, who is a consultant for ESA and heads a United Nations working group on near-Earth objects.

Be prepared

"Up to now, the US has taken the majority of the responsibility for dealing with this issue and I think it's time for other states to take on a more equitable share of that," he says.

Help will also come from two new US observatories designed to survey the entire sky visible from their locations every few days. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), will consist of four 1.8-metre telescopes, the first of which is already up and running in Hawaii. Plans are afoot to construct the 8.4-metre Large Synoptic Survey Telescope in Chile by 2015, though the project is still raising funds. These will improve the chances of an early detection and potentially extend warning times for 30-metre objects to more than a month. But even so, every ground-based lookout suffers from interference from the sun and moon.

A dedicated space telescope would fix this problem, but such a mission could cost more than a billion dollars. "We're talking about investing in an insurance policy," says Irwin Shapiro of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

Shapiro is leading a US National Research Council panel that by year's end will recommend a strategy to better address the threat from near-Earth objects. That study, along with the air force's report on its asteroid impact exercise, is intended to help the White House develop an official policy on the near-Earth object hazard by October 2010, which Congress has requested.

While asteroid impacts are much rarer than hurricanes and earthquakes, they have the potential to do much greater damage, Johnson warns: "It's not something I think there needs to be billions of dollars per year spent on, but it does warrant some priority in the list of things that we ought to be worried about." The cash would at least give us a better idea of when the next asteroid might strike. "From what we know today," he says, "it could be next week."

Comment: For a more in-depth study, read Meteorites, Asteroids, and Comets: Damages, Disasters, Injuries, Deaths, and Very Close Calls

Cosmic shock and awe: Fireball explodes over Argentina

Momento24
Tue, 29 Sep 2009 00:27 EDT

Yesterday afternoon the inhabitants of Mendoza, La Pampa, San Luis, and Cordoba saw a meteorite coming down the sky. It finally desintegrated with a loud explosion before it hit the earth.

The object, which initially scared the residents, was seen yesterday in the General Alvear Department. It could be a meteorite or space junk, but the place where it fell isn't known, according to what the Copernicus Institute said today.

From 18.30 there was a cloud in the sky and the explosion was felt almost by all people, asaid Julio Alcaraz, police officer of Santa Isabel, a town located 320 kilometers west of Santa Rosa and 40 miles south of the border with Mendoza.

The chief of the Copernicus Institute, Jaime Garcia, said that "by the color, it would apparently be a meteorite." He added that "the meteorite's location is unknown but according to the information collected it wouldn't have landed on Mendoza".

He defined meteorite as "any space object that wanders among the planets, the stars, and that enters the atmosphere.

"It was like a fireball," commented several neighbors to a local radio last night. Some Pampean residents said they photographed it and sent to it to the local media. In fact what is seen is a trail in the sky.

The object fell in the middle of the field in an area of 300,000 hectares which is uninhabited. The risks of fire outbrakes was immediately ruled out as it had been snowing all day long and it was very humid.

The Civil Defense chief of the commune, Roberto Trigues, confirmed that the raking "was held from 20 up to 23hs. They could establish the hypothetical triangulation with the apex at Punta del Agua, Agua Escondida and Chocico or Santa Isabel, a little more to the South, which would be the impact zone.

This explosion is produced before hitting the earth and logically, as it is an important explosion, it produces a blast of air which causes the shaking of glasses in the houses.

Finally, Trigues said that this is a very large area, so "I would say it might be hard to find something".

Jaime Garcia, amateur astronomer in charge of the Copernicus Institute in San Rafael, said "nothing can be confirmed until an object is found, but we can say that according to testimonies, it is very likely to be a metal object such as a meteor."

UK: Strange Fireball Seen in Night Sky

Malvern Gazette
Wed, 30 Sep 2009 16:19 EDT

A Bosbury man who witnessed a strange light in the sky on Saturday night is wondering if anyone else saw the same thing.

Mark Beard saw the orange glow at around 9.45pm to 10pm as he was standing outside his rural home.

He said: "I was at my back door looking east, and to my left, appearing above the tops of houses was a large fireball, a tenth the size of the moon."

He said it was orange and moved through the sky for about two or three minutes in a north-south direction. It then slowly started to fade and then disappear, fading out before it had reached the horizon in the south.

He said he had found news reports on the Internet of similar object being seen in Essex at about the same time on the same night.

"I've seen shooting stars and it didn't have the trail you see with them, but it was very, very bright," he said.

August 2009

noreply@blogger.com (Keit) — Tue, 18 Aug 2009 02:53:00 +0000

England: Scunthorpe - 'Fireball' spotted with parts falling off and all 'flowing' in the same direction

UK UFO Sightings
Sun, 02 Aug 2009 19:34 UTC

Posted: August 2, 2009

Date of Sighting: August 1st 2009
Time: 10pm

Witness Statement: I was stood in my garden having a fag and iI saw like a fire ball in the sky. I thought it was a plane on fire because it looked like parts of it had fallen off still on fire but they did not fall to the ground, they all flowed the same westerly direction. I believe it was any explanation.

The Perseids Are Coming

Red Orbit

Sat, 01 Aug 2009 18:11 UTC

© Space Weather
Looking northeast around midnight on August 11th-12th. The red dot is the Perseid radiant. Although Perseid meteors can appear in any part of the sky, all of their tails will point back to the radiant.

Earth is entering a stream of dusty debris from Comet Swift-Tuttle, the source of the annual Perseid meteor shower. Although the shower won't peak until August 11th and 12th, the show is already getting underway.

Don't get too excited, cautions Bill Cooke of NASA's Meteoroid Environment Office. "We're just in the outskirts of the debris stream now. If you go out at night and stare at the sky, you'll probably only see a few Perseids per hour."

This will change, however, as August unfolds.

"Earth passes through the densest part of the debris stream sometime on August 12th. Then, you could see dozens of meteors per hour."

For sky watchers in North America, the watch begins after nightfall on August 11th and continues until sunrise on the 12th. Veteran observers suggest the following strategy: Unfold a blanket on a flat patch of ground. Lie down and look up. Perseids can appear in any part of the sky, their tails all pointing back to the shower's radiant in the constellation Perseus. Get away from city lights if you can.

There is one light you cannot escape on August 12th. The 55% gibbous Moon will glare down from the constellation Aries just next door to the shower's radiant in Perseus. The Moon is beautiful, but don't stare at it. Bright moonlight ruins night vision and it will wipe out any faint Perseids in that part of the sky.

The Moon is least troublesome during the early evening hours of August 11th. Around 9 to 11 p.m. local time (your local time), both Perseus and the Moon will be hanging low in the north. This low profile reduces lunar glare while positioning the shower's radiant for a nice display of Earthgrazers.

"Earthgrazers are meteors that approach from the horizon and skim the atmosphere overhead like a stone skipping across the surface of a pond," explains Cooke. "They are long, slow and colorful - among the most beautiful of meteors." He notes that an hour of watching may net only a few of these at most, but seeing even one can make the whole night worthwhile.

Possible Meteorite Imaged by Opportunity Rover on Mars

Mars Today

Sat, 01 Aug 2009 21:57 UTC

This image of "Block Island" was taken on July 28, 2009, with the front hazard-identification camera on NASA's Mars Exploration Rover Opportunity.

The Opportunity rover has eyed an odd-shaped, dark rock, about 0.6 meters (2 feet) across on the surface of Mars, which may be a meteorite. The team spotted the rock called "Block Island," on July 18, 2009, in the opposite direction from which it was driving. The rover then backtracked some 250 meters (820 feet) to study it closer.

Scientists will be testing the rock with the alpha particle X-ray spectrometer to get composition measurements and to confirm if indeed it is a meteorite.

3D Debris On Jupiter

Space Weather

Sun, 02 Aug 2009 23:14 UTC

A dark cloud of debris from the July 19th impact on Jupiter continues to be visible through backyard telescopes. Now, for the first time, you can see it in 3D. Cross your eyes and behold:

Astrophotographer "Wah!" made the stereo pair using an 8-inch telescope in Hong Kong. He took two pictures of Jupiter four minutes apart, allowing the planet's rotation to provide the necessary right- and left-eye views. If you have trouble seeing the 3D effect, try staring at this larger version.

In 3D, the impact mark seems to be a hole in the clouds. In fact, it is a cloud, filled with dark cindery bits of a mystery-impactor that exploded like 2000 megatons of TNT. High altitude winds are spreading the debris around the south pole, enlarging the dark mark for easy viewing.

Amateur astronomers can monitor the cloud near Jupiter's System II longitude 210°. For the predicted times when it will cross the planet's central meridian, add 2 hours and 6 minutes to Sky and Telescope's predicted transit times for Jupiter's Great Red Spot. [sky map]

Comet Swarm Delivered Earth's Oceans?

Ker Than

National Geographic News
Wed, 05 Aug 2009 20:00 UTC

A barrage of comets may have delivered Earth's oceans around 3.85 billion years ago, a new study suggests.

Scientists have long suspected that Earth and its near neighbors were walloped by tens of thousands of impactors during an ancient event known as the Late Heavy Bombardment.

This pummeling disfigured the moon, leaving behind massive craters that are still visible, preserved for millennia in the moon's airless environment. But it's been unclear whether the impactors were icy comets or rocky asteroids.

Now, based on levels of a certain metal in ancient Earth rocks, a team led by Uffe Jorgensen of the Niels Bohr Institute in Denmark says comets were the culprits.

Whether Earth had oceans before any comets arrived has been intensely debated, Jorgensen noted.

Some experts say enough water could have existed from the moment Earth formed, while others argue that the young planet's heat would have vaporized any liquids.

"It's the kind of subject that can make scientists fight physically with one another," Jorgensen said.

His team thinks early Earth was just too hot to retain large bodies of water. But by the time of the Late Heavy Bombardment, things had cooled down, allowing meltwater from the flurry of comets to become the world's first seas.

"We may sip a piece of the impactors every time we drink a glass of water," the study authors write in their paper, which will be published in an upcoming issue of the journal Icarus.

Comets' Metal

Jorgensen and colleagues arrived at this conclusion after measuring the levels of iridium in surface and near-surface rocks from Greenland - some of the oldest known rocks in the world, dating back to the time of the bombardment.

Iridium is a scarce metal on Earth, but it's relatively common in comets and asteroids.

According to the team's calculations, iridium levels in the rocks around an asteroid impact should be about 18,000 parts per trillion.

A comet impact, meanwhile, should leave behind only about 130 parts per trillion. That's because comets would carry less metal, since they're mostly made of loosely packed water ice with some rocky debris.

Comets also strike Earth at higher speeds, because of their longer orbits around the sun.

As a result, "the explosion formed by a comet is more violent than from an asteroid, and the amount of material - including iridium - thrown back into space is larger," Jorgensen said.

The team found that the Greenland rocks contained about 150 parts per trillion of iridium, supporting the idea that comets were the main players in the Late Heavy Bombardment.

All that ice from the comet swarm then thawed to create a global ocean more than half a mile (about a kilometer) deep, the team calculates.

The moon, meanwhile, lacks an ocean because its gravity is much weaker than Earth's, so most if not all of the debris from a comet strike would be thrown back into space, Jorgensen said.

But Nicolas Dauphas, a geophysicist at the University of Chicago, isn't yet convinced that the bombardment featured comets, not asteroids.

The new study, he said, relies on too many estimates - such as the predicted amount of iridium deposited following an impact.

"I am afraid [they have] stretched their conclusions too far," Dauphas said.

Accidental Life?

Chandra Wickramasinghe, an astrobiologist at Cardiff University in the U.K. not involved in the new study, also supports the theory of an ancient comet bombardment.

And he thinks it's possible that comets seeded Earth not only with water but with life.

According to some controversial studies, the oldest evidence for life on Earth dates back to about 3.85 billion years ago, around the time of the Late Heavy Bombardment, he noted.

"It could be a coincidence, but to me it would be a remarkable coincidence," Wickramasinghe said.

Study co-author Jorgensen is inclined to agree.

"The [Late Heavy Bombardment] was an accident," he said. "If it had not happened, there would have been no water on Earth, and no life."

Triple asteroid system passes by Earth

NASA

Thu, 06 Aug 2009 06:13 UTC

© NASA/JPL/GSSR
Radar imaging at NASA's Goldstone Solar System Radar on June 12 and 14, 2009, revealed that near-Earth asteroid 1994 CC is a triple system.

Radar imaging at NASA's Goldstone Solar System Radar on June 12 and 14, 2009, revealed that near-Earth asteroid 1994 CC is a triple system. Asteroid 1994 CC encountered Earth within 2.52 million kilometers (1.56 million miles) on June 10. Prior to the flyby, very little was known about this celestial body. 1994 CC is only the second triple system known in the near-Earth population. A team led by Marina Brozovic and Lance Benner, both scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., made the discovery.

1994 CC consists of a central object about 700 meters (2,300 feet) in diameter that has two smaller moons revolving around it. Preliminary analysis suggests that the two small satellites are at least 50 meters (164 feet) in diameter. Radar observations at Arecibo Observatory in Puerto Rico, led by the center's director Mike Nolan, also detected all three objects, and the combined observations from Goldstone and Arecibo will be utilized by JPL scientists and their colleagues to study 1994 CC's orbital and physical properties.

The next comparable Earth flyby for asteroid 1994 CC will occur in the year 2074 when the space rock trio flies past Earth at a distance of two-and-a-half million kilometers (1.6 million miles).

Of the hundreds of near-Earth asteroids observed by radar, only about 1 percent are triple systems.

Mars Rover takes picture from Meteorite

nasa.gov

Fri, 07 Aug 2009 06:20 UTC

Composition measurements by NASA's Mars Exploration Rover Opportunity confirm that this rock on the Martian surface is an iron-nickel meteorite.

This image combines exposures from the left eye and right eye of the rover's panoramic camera to provide a three-dimensional view when seen through red-green glasses with the red lens on the left. The camera took the component images during the 1,961st Martian day, or sol, of Opportunity's mission on Mars (July 31), after approaching close enough to touch the rock with tools on the rover's robotic arm.

Researchers have informally named the rock "Block Island." With a width of about two-thirds of a meter (2 feet), it is the largest meteorite yet found on Mars. Opportunity found a smaller iron-nickel meteorite, called "Heat Shield Rock" in late 2004.

Perseid Meteor Shower Might Dazzle

Joe Rao

SPACE.com
Sun, 09 Aug 2009 00:27 UTC

For Northern Hemisphere observers, August is usually regarded as "meteor month," with one of the best displays of the year reaching its peak near midmonth.

That display is, of course, the annual Perseid Meteor Shower, beloved by everyone from meteor enthusiasts to summer campers. This year is expected to produce an above average number of "shooting stars" that could offer a rewarding experience to skywatchers around the globe.

There's just one problem: A bright moon will drown out fainter meteors.

The moon will be at last quarter the night of Aug. 13 and it will be at a rather bright waning gibbous phase a night or two earlier, seriously hampering observation of the peak of the Perseids, predicted to occur late on the nights of Aug. 11 and 12.

Moonrise on Aug. 11 comes at around 10:20 p.m., while on Aug. 12 it's around 10:50 p.m. The moon will be hovering below and to the left of the Great Square of Pegasus these nights and not all that far from the constellation Perseus, from where the meteors will appear to emanate (hence the name "Perseid").

Perseus, does not begin to climb high up into the northeast sky until around midnight; by dawn it's nearly overhead. But bright moonlight will flood the sky through most of those two key nights and will certainly play havoc with any serious attempts to observe these meteors.

Shower already underway

The Perseids are already around, having been active only in a very weak and scattered form since around July 17, as is typically the case for this annual shower.

But a noticeable upswing in Perseid activity traditionally begins during the second week of August, leading up to their peak. They are typically fast, bright and occasionally leave persistent trains. And every once in a while, a Perseid fireball will blaze forth, bright enough to be quite spectacular and more than capable to attract attention even in bright moonlight.

Unfortunately, because the moon was also at full phase on Aug. 5 it will always be above the horizon during the predawn morning hours (when Perseid viewing is best) in the days leading up to the peak. So even the gradual increase in the shower will be spoiled by moonlight.

The moon arrives at last quarter on Aug. 13 and thereafter its light becomes much less objectionable, but by that time the peak of the display has passed, leaving only a few lingering Perseid stragglers in its wake.

But nonetheless, the 2009 Perseids will be still be worth watching.

Comet crumbs

We know today that these meteors are actually the dross of the Swift-Tuttle comet. Discovered back in 1862, this comet takes approximately 130 years to circle the sun. And in much the same way that the Tempel-Tuttle comet leaves a trail of debris along its orbit to produce the spectacular Leonid Meteors of November, the Swift-Tuttle comet produces a similar debris trail along its orbit to cause the Perseids.

Indeed, every year during mid-August, when the Earth passes close to the orbit of Swift-Tuttle, the material left behind by the comet from its previous visits, ram into our atmosphere at approximately 37 miles (60 kilometers) per second and create bright streaks of light in our midsummer night skies.

And according to two meteor researchers, each working independently, 2009 could turn out to be an unusually intense Perseid year.

Mikhail Maslov of Russia has determined that within a matter of several hours on the morning of Aug. 12, the Earth will come close to three trails of dust shed by the Swift-Tuttle comet from three prior visits to the vicinity of the Sun (in 1610, 1737 and 1861). All three encounters will all occur within a roughly 4-hour time frame between 4 and 8 hours UT, which will be particularly favorable for eastern North America where this interval corresponds to midnight to 4 a.m. on Aug. 12; the constellation of Perseus will be gradually climbing the northeast sky during this time frame.

According to Maslov, the Earth will be passing only 87,000 miles (140,000 km) from the center of the 1610 trail at 8:07 UT (4:07 a.m. EDT).

In the absence of moonlight, an observer might see up to 200 meteors per hour around that time, a number that sadly - because of the bright moon - won't in 2009. Overall, though, the Perseids might still put on a good display despite the interfering moonlight, with at least the brighter meteors being visible to patient observers.

Another researcher, Jeremie Vaubaillon of Caltech, used a computer simulation to depict Earth's passage through the Perseids in 2009. Vaubaillon's simulation clearly shows Earth encountering significant meteor activity from about 0 hours UT on Aug. 12 through about 6 hours UT on Aug. 13, possibly suggesting better than average Perseid activity worldwide for both the late-night hours of Aug. 11 and Aug. 12, local times.

Is it safe?

Many years ago, a phone call came into New York's Hayden Planetarium. The caller sounded very concerned after hearing a radio announcement of an upcoming Perseid display and wanted to know if it would be dangerous to stay outdoors on the peak night of the shower (perhaps assuming there was a danger of getting hit by cosmic debris).

These meteoroids, however, are no bigger than sand grains or pebbles, have the consistency of cigar ash and are consumed dozens of miles above our heads. The caller was passed along to the Planetarium's then-Chief Astronomer, Dr. Kenneth L. Franklin (1923-2007).

Franklin quickly allayed any fears by cheerfully commenting that there are only two dangers from watching for Perseid meteors: getting drenched with dew and falling asleep!

* Top 10 Perseid Meteor Shower Facts
* Meteor Watching 101: Tips and terms
* Perseid Meteor Gallery 2004, 2006

Jupiter Impact Cloud Has Split Into Three Clouds

Space Weather

Sun, 09 Aug 2009 00:52 UTC

Debris from the July 19th mystery-impact on Jupiter has split into three clouds. The trifurcation is evident in this August 7th image taken by Rick Schrantz using a 10-inch telescope at his backyard observatory in Nicholasville, Kentucky:

Other observers have noticed the same thing. "There appear to be 3 distinct impact scars now, somewhat linear in shape and perhaps larger than previous days," reports Joel Warren of Amarillo, Texas. He took these pictures using an 8-inch telescope.

Jupiter's upper atmosphere is a dynamic place. The cindery impact debris appears to be caught up in a cascade of turbulent swirls and eddies, which is literally ripping the cloud apart. Amateur astronomers can monitor what happens next: The impact is located near Jupiter's System II longitude 210°. For the predicted times when it will cross the planet's central meridian, add 2 hours and 6 minutes to Sky and Telescope's predicted transit times for Jupiter's Great Red Spot.

more images: from Mike Salway of Central Coast, NSW Australia; from Raffaello Lena of Rome, Italy; from Alphajuno of League City, Texas; from Mike Hood of Kathleen, Georgia, USA

Radio Perseids

Space Weather

Sun, 09 Aug 2009 01:05 UTC

Awash in moonlight, the Perseid meteor shower is at present not very easy to see. Some observers have given up on looking, choosing instead to monitor the shower by means of radio. This plot from Dave Swan shows how he is counting more than 300 Perseid radio echoes per hour using a Yagi antenna and 55.25 MHz receiver in Bransgore, UK:

In the loudspeaker, each echo sounds like a little "ping." It is the reflection of a distant TV transmitter from the meteor's ionized trail. Forward scatter meteor detection, as this technique is called, is more sensitive than ordinary visual observation. Very small meteoroids are able to create a radio echo without leaving any trace of optical light in the sky. That's why Swan is counting 300 radio Perseids per hour while naked-eye observers are couting no more than about 20. Click here to monitor forward scatter stations around the world.

Something punching through Saturn's F ring captured on film

Discover Magazine
Sun, 09 Aug 2009 01:58 UTC

Phil Plait

It's not exactly clear what's going on here, even in this slightly zoomed shot. But it looks for all the world - or worlds - like some small object on an inclined orbit has punched through Saturn's narrow F ring, bursting out from underneath, and dragging behind it a wake of particles from the rings. The upward-angled structure is definitely real, as witnessed by the shadow it's casting on the ring material to the lower left. And what's with the bright patch right where this object seems to have slammed in the rings? Did it shatter millions of icy particles, revealing their shinier interior material, making them brighter? Clearly, something awesome and amazing happened here.

My first inclination (haha! Inclination! As always, I slay me) is to say that there isn't enough material in the rings to create what amounts to a hydrodynamic wake behind a moving object. When you move through air you leave a wake behind you, but there are gazillions of particles per cubic centimeter in the Earth's air at sea level. I would think that even in Saturn's ring, the density of particles wouldn't be enough to support a phenomenon like this.

But apparently, I'm wrong. Without doing a full-blown hydrodynamic calculation it's hard to say what's possible and what isn't. Cassini scientists are currently doing just that, in order to better understand what this odd image is trying to tell us.

And I have to wonder: is this a common occurrence? Is this object on an orbit that intersects the rings so that it plunges up through them and then again down into them every time it circles Saturn? If so, how does that affect the rings overall, especially over millions of years?

Or was this a singular event, some small object whose orbit was affected by a nearby massive moon, changing its path, putting it on a collision course with Saturn's mighty and vast ring system? That seems awfully unlikely...

... but when it comes to this weird, weird place, I've learned my intuition is monumentally inadequate. Nature, it turns out, has a far greater imagination than any mere human. We are fated, I think, to watch Nature unfold before us and try to figure it out after the fact.

But oh, isn't that the joy of science?

Something went through Saturn's ring - like the fist of an angry god

Bad Astronomy

Mon, 10 Aug 2009 17:04 UTC

Deep in the outer realms of our solar system, well over a billion kilometers away, something bizarre happened at Saturn's F ring.

I mean, seriously: what the hell happened here?

This is one of the latest pictures returned from the remarkable human achievement that is the Cassini spacecraft, a probe the size of a school bus that has been orbiting the ringed planet since 2004. It's returned one incredible picture after another, and lately - as Saturn's orbit has brought it to a point where the rings are nearly edge-on to the Sun - things have gotten not only spectacular but also really weird.

The rings are incredibly thin, only a few meters in thickness despite being hundreds of thousands of kilometers across. Over the past few months, as the Sun shines almost straight into the rings (instead of down on them), every bump and irregularity sticks out like, well, like a tree in the desert. Weird gravitational effects from Saturn's fleet of moons tune and resonate the countless particles making up the rings, creating beautiful waves and ripples.

But this, this is something new.

It's not exactly clear what's going on here, even in this slightly zoomed shot. But it looks for all the world - or worlds - like some small object on an inclined orbit has punched through Saturn's narrow F ring, bursting out from underneath, and dragging behind it a wake of particles from the rings. The upward-angled structure is definitely real, as witnessed by the shadow it's casting on the ring material to the lower left. And what's with the bright patch right where this object seems to have slammed in the rings? Did it shatter millions of icy particles, revealing their shinier interior material, making them brighter? Clearly, something awesome and amazing happened here.

My first inclination (haha! Inclination! As always, I slay me) is to say that there isn't enough material in the rings to create what amounts to a hydrodynamic wake behind a moving object. When you move through air you leave a wake behind you, but there are gazillions of particles per cubic centimeter in the Earth's air at sea level. I would think that even in Saturn's ring, the density of particles wouldn't be enough to support a phenomenon like this.

But apparently, I'm wrong. Without doing a full-blown hydrodynamic calculation it's hard to say what's possible and what isn't. Cassini scientists are currently doing just that, in order to better understand what this odd image is trying to tell us.

And I have to wonder: is this a common occurrence? Is this object on an orbit that intersects the rings so that it plunges up through them and then again down into them every time it circles Saturn? If so, how does that affect the rings overall, especially over millions of years?

Or was this a singular event, some small object whose orbit was affected by a nearby massive moon, changing its path, putting it on a collision course with Saturn's mighty and vast ring system? That seems awfully unlikely...

... but when it comes to this weird, weird place, I've learned my intuition is monumentally inadequate. Nature, it turns out, has a far greater imagination than any mere human. We are fated, I think, to watch Nature unfold before us and try to figure it out after the fact.

But oh, isn't that the joy of science?

Comment: Perhaps, if it doesn't come smashing on top of your head.

Confession: NASA can't keep up with killer asteroids

Seth Borenstein

Associated Press
Wed, 12 Aug 2009 20:18 UTC

NASA is charged with seeking out nearly all the asteroids that threaten Earth but doesn't have the money to do the job, a federal report says.

That's because even though Congress assigned the space agency this mission four years ago, it never gave NASA money to build the necessary telescopes, the new National Academy of Sciences report says. Specifically, NASA has been ordered to spot 90 percent of the potentially deadly rocks hurtling through space by 2020.

Even so, NASA says it's completed about one-third of its assignment with its current telescope system.

NASA estimates that there are about 20,000 asteroids and comets in our solar system that are potential threats to Earth. They are larger than 460 feet in diameter - slightly smaller than the Superdome in New Orleans. So far, scientists know where about 6,000 of these objects are.

Rocks between 460 feet and 3,280 feet in diameter can devastate an entire region but not the entire globe, said Lindley Johnson, NASA's manager of the near-Earth objects program. Objects bigger than that are even more threatening, of course.

Just last month astronomers were surprised when an object of unknown size and origin bashed into Jupiter and created an Earth-sized bruise that is still spreading. Jupiter does get slammed more often than Earth because of its immense gravity, enormous size and location.

Comment: And recently Venus too: Smashing days! New bright spot observed on Venus

Disaster movies like "Armageddon" and near misses in previous years may have scared people and alerted them to a serious issue. But when it comes to doing something about monitoring the threat, the academy concluded "there has been relatively little effort by the U.S. government."

And the U.S. government is practically the only government doing anything at all, the report found.

"It shows we have a problem we're not addressing," said Louis Friedman, executive director of the Planetary Society, an advocacy group.

NASA calculated that to spot the asteroids as required by law would cost about $800 million between now and 2020, either with a new ground-based telescope or a space observation system, Johnson said. If NASA got only $300 million it could find most asteroids bigger than 1,000 feet across, he said.

But so far NASA has gotten neither sum.

Comment: Perhaps because the US is busy spending all that money on the so-called 'wars'?

It may never get the money, said John Logsdon, a space policy professor at George Washington University.

"The program is a little bit of a lame duck," Logsdon said. There is not a big enough group pushing for the money, he said.

At the moment, NASA has identified about five near-Earth objects that pose better than a 1-in-a-million risk of hitting our planet and being big enough to cause serious damage, Johnson said. That number changes from time to time, usually with new asteroids added and old ones removed as more information is gathered on their orbits.

The space rocks astronomers are keeping a closest eye on are a 430-foot diameter rock that has a 1-in-3,000 chance of hitting Earth in 2048 and a much-talked about asteroid, Apophis, which is twice that size and has a one-in-43,000 chance of hitting in 2036, 2037 or 2069.

Last month, NASA started a new Web site for the public to learn about threatening near-Earth objects.

Comment: Maybe NASA isn't keeping track of them, but someone is and they're not gonna tell us when something is about to hit.

Aorounga Impact Crater, Chad

Earth Observatory

Thu, 13 Aug 2009 02:49 UTC

© NASA
Astronaut photograph ISS020-E-26195 was acquired on July 25, 2009, with a Nikon D3 digital camera fitted with an 800 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 20 crew.

Aorounga Impact Crater is located in the Sahara Desert, in north-central Chad, and is one of the best-preserved impact structures in the world. The crater is thought to be middle or upper Devonian to lower Mississippian (approximately 345 - 370 million years old) based on the age of the sedimentary rocks deformed by the impact. Spaceborne Imaging Radar (SIR) data collected in 1994 suggests that Aorounga is one of a set of three craters formed by the same impact event. The other two suggested impact structures are buried by sand deposits.

The concentric ring structure of the Aorounga crater - renamed Aorounga South in the multiple-crater interpretation of SIR data - is clearly visible in this detailed astronaut photograph. The central highland, or peak, of the crater is surrounded by a small sand-filled trough; this in turn is surrounded by a larger circular trough.

Linear rock ridges alternating with light orange sand deposits cross the image from upper left to lower right; these are called yardangs by geomorphologists. Yardangs form by wind erosion of exposed rock layers in a unidirectional wind field. The wind blows from the northeast at Aorounga, and sand dunes formed between the yardangs are actively migrating to the southwest.

The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth.

Earth could be blindsided by asteroids, panel warns

David Shiga

New Scientist
Wed, 12 Aug 2009 16:00 UTC

© NEAR Project/NLR/JHUAPL/Goddard SVS/NASA
Asteroid Eros, seen here by NASA's NEAR spacecraft, is 33 kilometres wide, making it the second largest near-Earth asteroid

Existing sky surveys miss many asteroids smaller than 1 kilometre across, leaving the door open to damaging impacts on Earth with little or no warning, a panel of scientists reports. Doing better will require devoting more powerful telescopes to asteroid hunting, but no one has committed the funds needed to do so, it says.

Near-Earth asteroids larger than 1 kilometre across could blast huge amounts of sunlight-blocking dust into Earth's atmosphere in an impact, causing devastating climate change. The US Congress asked NASA in 1998 to find 90 per cent of those in this size range within 10 years, a goal that has now nearly been reached.

Astronomers have now found 784 of them, mostly using telescopes funded by NASA. That works out to 83 per cent of the 940 estimated to be out there by astronomer Alan Harris of the Space Science Institute in Boulder, Colorado.

But asteroids below 1 kilometre in size can cause serious harm, too, and they hit Earth more frequently because they are more numerous. To address the small-asteroid threat, Congress told NASA in 2005 to find 90 per cent of the near-Earth asteroids larger than 140 metres across by 2020.

NASA asked the US National Research Council in 2008 to figure out the best way to survey small asteroids and meet the 2020 goal. Now, the NRC panel has issued an interim report, saying that without new money for more powerful surveys, NASA will not be able to meet the goal.

Surprise hit

"To achieve this goal, or to even come close to achieving it, new facilities capable of detecting fainter asteroids and having wider fields of view to cover larger portions of the sky each night are required," the report says.

Panel leader Irwin Shapiro of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, says there is wide agreement on this point. "Pretty well everyone agrees now that [just] continuing with what we have, there's no way we could reach the 2020 goal," he told New Scientist.

The report also points out that existing surveys are designed to gradually build up a catalogue of near-Earth objects over time, not to watch out for incoming asteroids that are just days or weeks from colliding with our planet.

Small asteroids could easily slip past existing surveys unnoticed until the moment of collision because telescopes currently devoted to the task are only capable of imaging a small part of the sky each night. And even then, clouds can prevent them from spotting asteroids, says Timothy Spahr of the Minor Planet Center in Cambridge, Massachusetts, a central clearinghouse for asteroid and comet data.

'No free lunch'

Asteroids approaching from the direction of the sun would also be missed, at least by ground-based telescopes, says Alan Harris. Sending a telescope to another vantage point in space could overcome this problem. "[But] it could be seriously expensive," says Harris. "So one must ask, 'What's it worth?'"

"There is no free lunch," Shapiro agrees. But he adds, "We're talking about investing in an insurance policy."

A comet or asteroid as small as 30 metres across is thought to have exploded in the atmosphereMovie Camera over Siberia in 1908, unleashing hundreds of times the energy of the nuclear bomb dropped on Hiroshima, Japan, in 1945, and flattening trees in a zone dozens of kilometres across.

A small asteroid impact in the ocean could also flood coastal cities by triggering huge waves, though scientists are still debating how far such waves could travel before petering out.

Comment: See also: Confession: NASA can't keep up with killer asteroids

NASA Researchers Make First Discovery of Life's Building Block in Comet

Bill Steigerwald

NASA Goddard Space Flight Center
Tue, 18 Aug 2009 01:06 UTC

© NASA/JPL
This is an artist's concept of the Stardust spacecraft beginning its flight through gas and dust around comet Wild 2. The white area represents the comet. The collection grid is the tennis-racket-shaped object extending out from the back of the spacecraft.

NASA scientists have discovered glycine, a fundamental building block of life, in samples of comet Wild 2 returned by NASA's Stardust spacecraft.

"Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet," said Dr. Jamie Elsila of NASA's Goddard Space Flight Center in Greenbelt, Md. "Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

Elsila is the lead author of a paper on this research accepted for publication in the journal Meteoritics and Planetary Science. The research will be presented during the meeting of the American Chemical Society at the Marriott Metro Center in Washington, DC, August 16.

"The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare," said Dr. Carl Pilcher, Director of the NASA Astrobiology Institute which co-funded the research.

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins.

Stardust passed through dense gas and dust surrounding the icy nucleus of Wild 2 (pronounced "Vilt-2") on January 2, 2004. As the spacecraft flew through this material, a special collection grid filled with aerogel - a novel sponge-like material that's more than 99 percent empty space - gently captured samples of the comet's gas and dust. The grid was stowed in a capsule which detached from the spacecraft and parachuted to Earth on January 15, 2006. Since then, scientists around the world have been busy analyzing the samples to learn the secrets of comet formation and our solar system's history.

"We actually analyzed aluminum foil from the sides of tiny chambers that hold the aerogel in the collection grid," said Elsila. "As gas molecules passed through the aerogel, some stuck to the foil. We spent two years testing and developing our equipment to make it accurate and sensitive enough to analyze such incredibly tiny samples."

Earlier, preliminary analysis in the Goddard labs detected glycine in both the foil and a sample of the aerogel. However, since glycine is used by terrestrial life, at first the team was unable to rule out contamination from sources on Earth. "It was possible that the glycine we found originated from handling or manufacture of the Stardust spacecraft itself," said Elsila. The new research used isotopic analysis of the foil to rule out that possibility.

Isotopes are versions of an element with different weights or masses; for example, the most common carbon atom, Carbon 12, has six protons and six neutrons in its center (nucleus). However, the Carbon 13 isotope is heavier because it has an extra neutron in its nucleus. A glycine molecule from space will tend to have more of the heavier Carbon 13 atoms in it than glycine that's from Earth. That is what the team found. "We discovered that the Stardust-returned glycine has an extraterrestrial carbon isotope signature, indicating that it originated on the comet," said Elsila.

The team includes Dr. Daniel Glavin and Dr. Jason Dworkin of NASA Goddard. "Based on the foil and aerogel results it is highly probable that the entire comet-exposed side of the Stardust sample collection grid is coated with glycine that formed in space," adds Glavin.

"The discovery of amino acids in the returned comet sample is very exciting and profound," said Stardust Principal Investigator Professor Donald E. Brownlee of the University of Washington, Seattle, Wash. "It is also a remarkable triumph that highlights the advancing capabilities of laboratory studies of primitive extraterrestrial materials."

The research was funded by the NASA Stardust Sample Analysis program and the NASA Astrobiology Institute. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Stardust mission for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, developed and operated the spacecraft.

Canada: Ontario - Two huge balls of fire traveling east

Peter Davenport
NUFORC
Wed, 05 Aug 2009 23:45 UTC

Occurred: 8/1/2009 21:30 (Entered as : aug 1 2009 21:30)
Reported: 8/2/2009 6:26:00 AM 06:26
Posted: 8/5/2009
Location: Oakville (Canada), ON
Shape: Fireball
Duration: 5 mins

Two large balls of fire appearing in sky traveling east

Two bright red fireballs appeared traveling east close to Upper Middle Road and Third Line, flying over the Abbey Park Recreation Center. Very bright, like on fire, but looks like going east, not falling down, one after another about 3 mins apart, then disappearing. Did not look like a meteor, looked like huge ball of fire, very red in colour. Not an airplane, perhaps space junk burning upon re-entry, but then why wouldn't the fireballs continue descent to the ground, why keep going east? Silent, no engine sounds.

August 24th Fireball over Canada - Possible Meteorite?

Argusrocks.com

Tue, 25 Aug 2009 18:21 UTC

Occasionally, I like to search Twitter for meteorite or meteorites. Last night, a bunch of people in Canada suddenly started talking about meteorites. A large meteor was seen - also known as a fireball or bolide.

Those of us in the meteorite hobby know that when someone says they saw a meteorite fall "nearby", it could mean almost anything - there is a common confusion between distance and angular distance. Still, with this many witnesses, it's certainly possible that something reached the ground last night.

Below, I've compiled some of the highlights from Twitter. I've used ellipsis to indicate multiple tweets from the same user.

OTerry: Just saw a massive firery meteorite fall in north york. I wonder where it landed. It was either really big or very close.

derekpurdy: Saw an amazing meteor in the sky tonight it was lit up for a second or two. Bright Green/blue watched it break up, amazing. #Meteor #Ontario ... it was something else! Never seen a meteor like that. Wow, all I can say is wow. (user is at 44.264135, -78.064328)

ChaiLatteAddict: I think I just a meteor! It made a bang and it fell from the sky and it was blue-ish/green-ish. Please tell me how to confirm this! ... @ptc555 I saw it east of the west part of Montreal, so it make sense we saw the same thing if you're in Ont. Thank god you saw it too! ... Meteor sighting in Canada. I'm thinking about going home to watch the news all night. I wanna know where it fell and how big it is! ... I love the power of Twitter, we all saw something thinking we were crazy but we talk about it and it's an amazing feeling.

markdelete: i totally saw that possible meteor tonight in the sky. blue flash with red center. pretty crazy.

jsat2028: @argusrocks Hi, I saw it land! It was as high as a telephone pole when I saw it I was no more than 20 yards away. Report it, to who? ... I could see the ripples from the heat it was blue, looked like a force field, and the head was a fireball.

mackaytaggart: @kentboniface I work at a talkradio station in Toronto....we're getting a lot of calls about the meteorite. Where were you when you saw it? ... @MitchMirsky I work @ a Toronto radio station. Getting lots of calls from listeners who reported seeing it. May have landed in Barrie ON.

kentboniface: Just saw a meteorite large enough to light up the entire sky. Looked like lightning, but not a cloud in the sky.

MitchMirsky: Driving home tonite, we saw a meteorite land about 300 yards away.

ellehether: saw the most breathtaking meteor tonight! blue, green and orange! it was hugeeee!

ptc555: @colorsounds you saw the meteorite in rochester? i saw it in toronto! ... @mackaytaggart i saw the meteorite from Etobicoke (royal york and eglinton). i was looking north.

colorsounds: Falling meteorite in #roc, burned green, about 8:50pm, very big and bright!

LouisSabourin: @argusrocks I saw at about 9 pm a meteorite: very impressive from Gatineau Qc was looking south-west: Ottawa, maybe

M_A_R_A #meteor: saw a giant bal of fire at St. Clair & Ossington....it was awesome!

DGConroy: Saw the meteor come across at Yonge and Eg... looked very close! (user is at 43.646557, -79.388714)

itemtrader: I just the the meteor to ! thought i was crazy - it was bright

craigebrown: I too saw a meteor flash across the sky. Very quick, very bright.

vdiddy1103: I just saw a shooting star...or a comet...or a meteor. I wish Astronomy wasn't boring as f - , maybe I would have learned something.

sarahhp89: May Have Just Seen Some Sort Of Meteor Flash :0 Stoked!

fadersmusic: Decided to go investigate am old haunted hotel called the regal constellation and witnessed a very impressive meteor fireball in the skies

ChrisDawe: Holy poo. Just saw what had to be a meteor burning up over Toronto! Anyone else see it?

CopySix: Just saw a small meteorite (shooting star) come down from my Barrie backyard - so close you could actually 'hear' it.

nevdawg: @ChaiLatteAddict I saw it from Milton, just south of Toronto. Pretty incredible.

BenTFleming: holy s - , I just saw a meteor crash.

memories_music: Just saw a meteorite!!!

dvasmusique: holy shit comet in toronto! #toronto ... yeah i saw it ... spectacular ... i was on my way to District 9 and i saw it over my apt. building on queen near bellwoods

So, will anything be found? It couldn't hurt to look! If anyone has more information about this sighting, please contact me. If anything is found, I'm going to call this "the Twitter meteorite".

Red Fire Ball Hovers & Then Bolts Out of Sight

UFOs Northwest

Wed, 26 Aug 2009 23:36 UTC

Date of Sighting: August 21, 2009
Time of Sighting: 5:30 AM PDT
Location of Sighting: Grand Rapids, Michigan

Description: I walked passed my balcony doors to see what looked like a big red fire ball hovering in the sky over Grand Rapids near the Ford Airport. I grabbed my digital camera and it's battery which was charging as I put the battery in my camera the object turned slightly side ways and then bolted out of sight. It moved so fast I didn't have time to snap one darn picture.

Note: A hovering fire ball that bolts out of sight isn't easily explainable. It is too bad that the witness wasn't able to get a photo.

England: Meteor seen above Cheltenham

This is Gloucestershire

Fri, 28 Aug 2009 23:45 UTC

A church worker believes he has photographed a meteor blazing a trail above Cheltenham.

Matthew Pinless, 31, from Fairview, spotted the fast-moving object in the sky while walking along Glenfall Street in Cheltenham at about 5pm on Tuesday.

He said: "I was walking along the road with my young son and I spotted this object moving through the sky.

"At first I thought it was a plane, but then I could see it was moving too quickly for that.

"I managed to grab my phone and take a photograph, but it disappeared behind a cloud and never came out the other side.

"I don't subscribe to the UFO theory, so I am fairly sure it was a meteor, but I would be interested to hear if anybody else saw it in the sky."

'Fiery' meteor sighted in New Zealand

Shahra Walsh

The Press
Fri, 28 Aug 2009 23:18 UTC

A fiery meteor blazed a trail through the skies this morning, with sightings reported from Christchurch to Rotorua

Zoe Battersby was out for an early walk along Jimmy Amers beach in Kaikoura at around 6.10am when she noticed a "very large meteor".

"It was very bright - the size of a streetlight. It looked like it fell into the sea," she said.

Alan Gilmore, resident superintendent of the University of Canterbury Mt John Observatory said meteors enter the atmosphere over New Zealand "several times a year" but he doubted that the rock made it to the ground or water level.

"This meteor is very typical, and often they burn up at about 70kms up. It's very rare for them to actually land. They are coming into a thicker atmosphere, traveling at 30km a second. The friction is strong and they slow up and start to break up. It's like throwing a stone at a concrete path," he said.

Gilmore said as the meteor breaks up, witnesses often see a bright flash known as a 'terminal fireball'.

He said meteors "burning up coming through air - white hot with friction - start to glow". Meteors could be seen from as far as 100kms up and could be seen from almost 1000kms away.

"They are spectacular, often a bright white centre which is the actual rock, - a tiny, brilliant star - with a teardrop-shaped glow that's brilliant emerald green caused by the oxygen and the radiation coming off the rock," he said.

Gilmore said on the rare occasion that a meteor lands - then becoming known as a meteorite - its arrival is often heralded with a sonic boom caused by the temperature layers that exist closer to the surface, below 60kms.

Because of the range of reported sightings, Gilmore expected the meteor entered the atmosphere somewhere over the North Island.

"The impression of closeness is deceptive. Because they are bright, people think [the meteorite] landed a couple of paddocks away.

England: Meteor seen above Cheltenham

This is Gloucestershire

Fri, 28 Aug 2009 23:45 UTC

England: Pill Near Bristol - Two meteroites spotted, followed by several aircraft

UK UFO Sightings

Sat, 29 Aug 2009 23:08 UTC

Posted: August 29, 2009

Date of Sighting: Sunday 23rd August
Time: 6 am- 7am

Witness Statement: It looked like 2 meteorites heading downwards at a five o'clock angle visible to the North East with a smoke tail behind. This was at around 6am. Within 10 minutes the sky was filled with aircraft, over a dozen some leaving contrails, two jets leaving long chemical trails. Several craft headed directly North East and were silent and left no trail at all. All planes seemed to be heading or situated to the West. Could it all be related?

US: Huge Green Fireball Descends From Sky

UFOs Northwest

Sun, 30 Aug 2009 12:50 UTC

Date of Sighting: August 30, 2009
Time of Sighting: 12:50 AM PDT
Location of Sighting: Yakima, Washington

Description:

We just saw something falling from the sky in Yakima, Washington. At 12:50 AM my mom, my boyfriend and myself were outside in her front yard looking through our telescope at planets. He was bent down adjusting the lens and my mom and I were looking at the skies. All of a sudden - out of nowhere - something fell from the skies just a couple miles from us. We live in a nice neighborhood and didn't want to take off racing after it so we just stood there screaming out about how shocked we were at this sudden sighting. Normally, we would think it was a falling star except it was not white. It was on fire and it was smoking.

It had a long green trail behind it. You could see green and red flames trailing flames behind it. To me, it looked liked a meteor crashing, but my boyfriend thought it might be a falling satellite or a small plane crashing. We never actually heard a crash. There was no noise. If you hold a dinner plate out against the sky, that was the size of the object and it had 30 to 40 feet of flames behind it.

Could it be a crashed UFO? It seemed controlled by the way it was being steered. The sighting lasted around 20 seconds. I didn't have my camera on me this time! It was mid fast. It was obviously on fire. It trailed an almost straight line not like an arc like a shooting star. I am going to watch the news. Could you keep me informed if anyone else reports this?

Additional Report (In Response to Questions):

It was headed north to south. We lost sight at the roof of a house on the south side (of our home). On the same note my mom and I drove around looking for this "meterorite" which is exactly what I thought it was, but stumbled upon something else very strange (20 minutes after the sighting).

I am reviewing the pictures right now and will send them tomorrow if there is anything to it. I want to go the same location tonight (of possible landed object) to make sure before submitting a formal report. I am not sure if it is even related to the "meteor". I can submit the pictures anyway (within this e-mail) if you'd like.

Note:

This sure sounds like a meteorite. However, no other reports have been received. A check of the local media in the Yakima has not revealed any other sightings. Anyone who viewed this object or has seen "landing or crash debris" in the Yakima area is urged to file a report.