Ben Langford
Northern Territory News
Thu, 01 May 2008 13:59 EDT
FIVE mine workers are convinced they saw a UFO fly over them on a remote Territory island.
Mine maintenance worker Arnold Murray said a bright object whizzed
over the Gemco mine site on Groote Eylandt as he and his colleagues
started the night shift last Friday.
Mr Murray, 32, said the bright light was slightly higher than a plane coming to land -- but it was silent.
He and four workmates were at the mine site at 7.15pm when he saw an object flying towards them.
''I noticed a star in the sky and it was getting closer,'' he said.
''As it approached I realised it was at plane level.
''Four other lads walked out of the office and we watched it for a
little while. It was vertical from us, there were no flashing lights or
noise.
''The plant's pretty quiet at night. (It made) no noise whatsoever.
''All of a sudden it shot off and left a long orange trail behind it. That orange trail just faded out like a shooting star.''
Mr Murray said they wanted to know what flew over their heads in the
night: ''It wasn't a chopper, it wasn't a plane, we knew that much, and
it definitely wasn't a shooting star.''
''It blew us out of the water.''
Defence spokeswoman Kelly Cooper said the object was not a military
plane: ''There were no military aircraft flying in that area at that
time on that day,'' she said.
She said any navy ships letting off flares would have been at least 200 nautical miles off shore.
Groote Eylandt, in the Gulf of Carpentaria, is near one of the first
and most famous UFO sightings in Australia -- the ''light wheel''
reported on January 23, 1964.
Sailors on a vessel off the northeast point of the island reported
seeing a circle of pulsing lights rotating clockwise, and they said
their compass went ''haywire''.
'Sonic boom' preceded 5.2 quake near Burnt Ranch, Northern California
Carol Harrison
The Eureka Reporter
Thu, 01 May 2008 14:10 EDT
A magnitude-5.2 earthquake, centered 11 miles east southeast of Willow Creek, jolted the North Coast at 8:03 p.m. on Tuesday.
The Unites States Geological Survey termed it a level VI temblor with a strong shake and light damage.
A magnitude-2.0 aftershock hit five minutes later, 16 miles to the east of Willow Creek.
"It was sort of like a sonic boom," said Brenda Simmons of SkyCrest
Lake resort in Burnt Ranch. "It was a very loud noise before the house
started shaking. It was pretty scary, the biggest thing I've ever felt
here. (It) lasted 10 seconds max. I didn't feel the aftershock."
"We felt it good," said Terri Castner of Willow Creek. "It was a
short one with a heavy shake. We've got a free-floating ceiling fan and
it was rocking and rolling."
Castner's cat raced off her lap at the first vibration; a gentleman
shopping in the Willow Creek Ray's Food Place sprinted for the door.
"Everyone had time to go outside and come back and the glass shelf
was still shaking," longtime Ray's cashier Ginger Reeves said. "It was
a hard jolt, but things kept swaying for a couple minutes afterwards.
We had a few things fall off the shelf. Nothing major. It wasn't as bad
as the big one in Ferndale a few years ago. That knocked me off my
feet."
"I thought it was me at first," Janel Trunkey at Willow Creek Pizza
Factory said. "I thought it was pretty heavy. We only had one person in
here at the time. He was shocked."
Trunkey said a few things fell of the wall. Simmons said she lost
telephone service for 10 minutes, but her rattling dishes came through
undamaged.
Simmons said one concerned caller from the Forest Service put her at the center of the quake.
"I've felt earthquakes before, but never heard that loud of a noise
before," she said. "My father-in-law thought it was quite exciting. I
thought it was a little scary myself."
Science Daily
Fri, 02 May 2008 13:03 EDT
The sun's movement through the Milky Way
regularly sends comets hurtling into the inner solar system --
coinciding with mass life extinctions on earth, a new study claims. The
study suggests a link between comet bombardment and the movement
through the galaxy.
 |
| ©Artby Don Davis / Courtesy of NASA |
| A
large body of scientific evidence now exists that support the hypothesis that a major asteroid or comet impact occurred in the Caribbean region at the boundary of the Cretaceous and Tertiary periods in Earth's geologic history. Such an impact is suspected to be responsible for the mass extinction of many floral and faunal species, including the large dinosaurs, that marked the end of the Cretaceous period. |
Scientists at the Cardiff Centre for Astrobiology built a computer
model of our solar system's movement and found that it "bounces" up and
down through the plane of the galaxy. As we pass through the densest
part of the plane, gravitational forces from the surrounding giant gas
and dust clouds dislodge comets from their paths. The comets plunge
into the solar system, some of them colliding with the earth.
The Cardiff team found that we pass through the galactic plane every
35 to 40 million years, increasing the chances of a comet collision
tenfold. Evidence from craters on Earth also suggests we suffer more
collisions approximately 36 million years. Professor William Napier, of
the Cardiff Centre for Astrobiology, said: "It's a beautiful match
between what we see on the ground and what is expected from the
galactic record."
The periods of comet bombardment also coincide with mass extinctions, such as that of the dinosaurs 65 million years ago. Our present position in the galaxy suggests we are now very close to another such period.
While the "bounce" effect may have been bad news for dinosaurs, it
may also have helped life to spread. The scientists suggest the impact
may have thrown debris containing micro-organisms out into space and
across the universe.
Centre director Professor Chandra Wickramasinghe said: "This is a
seminal paper which places the comet-life interaction on a firm basis,
and shows a mechanism by which life can be dispersed on a galactic
scale."
The paper, by Professor Napier and Dr Janaki Wickramasinghe, is to be published in the Monthly Notices of the Royal Astronomical Society.
Adapted from materials provided by Cardiff University, via EurekAlert!, a service of AAAS.
My Dark Sky
Fri, 02 May 2008 16:33 EDT
A meteoroid is a solid object - usually are dust particles or debris from comets - that floats around in space.
When meteoroid enters and burns in the Earth's atmosphere, the visible streak in the sky is known as a meteor.
A meteorite is the meteoroid that survives and reaches Earth's surface.
An increase in the number of meteors at a particular time is called a meteor shower.
If we trace back the path of the meteors during a meteor shower, we
will find that all the meteors seem to originate from a point in the
sky. This point is known as the radiant.
Zenith Hourly Rate (ZHR) of a meteor shower is the
number of meteor an observer would see in an hour under a dark sky with
limiting magnitude of 6.5 and if the radiant was in the zenith. In
reality the rate which can effectively be seen is always lower as the
radiant is closer to the horizon and it also depends on the local
weather condition.
~~~~~~~~~~
Meteors appear as fast-moving streaks of light in the night sky that
usually will only last about a second or two. They are commonly
referred to as "falling stars" or "shooting stars". Sometimes meteor
may even leave a trail behind.
The vast outer space is actually not empty as it seems to be; there
are a lot of dust particles, tiny grains of sand and ice floating
around in space. When these particles or meteoroids come too close to
Earth, Earth's gravity will pull them into the atmosphere, at a speed
of 10 to 70 kilometres per second, to produce streaks of light in the
night sky known as meteors.
Most meteors will completely burn up in the atmosphere at an
altitude of 100 kilometres. However, some bigger chunk of meteoroids
may survive the trip through the atmosphere and reach the ground. These
remnants are known as meteorites.
What is Meteor Shower?
On a normal night we can typically see a few meteors per hour. This
type of meteors is called the sporadic meteors. However, at certain
times of the year the rate of observable meteors is much higher. These
periods are called meteor showers.
Most meteor showers have their origins with comets.
Comets are primarily composed of ice and dust and when they approach
the Earth, the Sun's heat will evaporate the ice and they will shed an
icy, dusty debris stream which is then distributed along their orbits.
When our Earth passes through a comet's orbit, these left-over comet
debris will "bombards" Earth and causes the rate of meteors increases.
Due to Earth orbit around the Sun, we will roughly be at the same
location in space every year. Hence meteor showers will occur almost
the same time each year when Earth crosses the comet's orbit. The
different between the yearly showers is related to how close the
comet's orbit to ours and how long ago the debris was ejected.
Why is Meteor Shower named after Constellation?
During a meteor shower, if we observe carefully, we will find that
the path of the meteors seem to radiate from a point in the sky. This
point is called the radiant of the meteor shower and is just a
perspective effect. Actually all the meteors enter the Earth's
atmosphere in a parallel path, but from our Earth perspective, the
meteors appear to come from the radiant.
Meteor shower is named based on the location of their radiant.
For example, if the radiant is located in constellation Perseus, the
particular meteor shower is known as the Perseids. If there is more
than one meteor shower in a constellation, then the shower is named
after the bright star nearest to the radiant. For example, the Eta
Aquarids and Delta Aquarids meteor shower are both from the
constellation Aquarius.
How to observe Meteor Shower?
All you need to enjoy a meteor shower is just your naked eyes. No equipment is needed!
* Find a dark, safe and unobstructed observing site.
* Bring along star chart, red-light torchlight, food & drinks, jacket, ground-mat or sleeping bag.
* When you reach the observing site, find a place that is not easily disturbed by others.
* Check your direction and use the star chart to find the location of the radiant in the sky.
* Find a comfortable position to sit or lie down while waiting for
the meteor to appear. The best position is to lie down flat on the
ground so that you will cover the maximum area of the sky.
Why there are more Meteors after Midnight?
When Earth orbit around the Sun, basically meteoroids enter the
Earth's atmosphere from all direction. The velocity of Earth around the
Sun is about 30 km/s and the meteoroids' velocity is averagely 40 km/s.
Refer to the diagram, before midnight, the meteors are catching up
with Earth from the back, hence the velocity of the meteor will be the
different between the Earth's orbital velocity and the meteoroids'
velocity, which is roughly 10 km/s.
 |
| ©Unknown |
| Meteor before & after midnight |
After midnight, the meteors are heading straight to Earth, so the
velocity now is the total of both the Earth and meteoroids' velocity,
which is equal to 70 km/s.
Hence, before midnight, only those meteoroids moving faster than
Earth will catch up, so the amount of meteor seen is lesser. Also, the
velocity of the meteor is lower before midnight, so the meteor will be
dimmer during this time.
~~~~~~~~~~
Click here for handout on Meteor Shower in both English and Chinese. You are welcome to use it as teaching or handout material to the public.
Asteroids - How real is the threat?
Sskankdragon
Skankdragon's blog
Tue, 29 Apr 2008 17:24 EDT
The Doomed and the Blind
As politicians sit squabbling in Washington, deliberating and
deciding, an asteroid 4 kilometers across is thundering through space
at 15 miles per second. It was forged in a galactic maelstrom millions
of years ago from molten metal, and now it tumbles through space with
malevolent indifference. People sit unaware of an impending disaster,
carrying on their daily activities while extinction encroaches. It
won't just be the extinction of a few species, or a few million people,
but all life will be wiped off the face of the earth within hours. Our
planet will become a barren waste for millions of years, void of
vibrant life and wonder.
 |
| Itokawa asteroid |
Is an awful scenario like this really plausible? The answer
is yes. The threat is very real and the evidence is in the scars our
earth bears on the surface, the massive craters on the moon, and the
giant wounds on Mars. You would expect that something so catastrophic and horrible for our species and planet would demand attention from lawmakers; wrong.
Although our government is well-informed by agencies like NASA, it has
neglected to properly fund Near Earth Object (NEO) programs, and it
could lead to our destruction. An asteroid impact is a natural disaster
we can actually prevent, and if our representatives don't take steps to
improve our warning systems, we will suffer the same fate as the
dinosaurs.
As Congress approves billions of dollars for the war in
Iraq, they reject a program which would well-equip us to deal with the
NEO threat. The cost of the program runs from $300 million to $1.1 billion (Shoemaker), less than the cost of one B-2 stealth bomber at $1.157 billion (Scott).
The lower cost would cover using or modifying existing space telescopes
to look for potentially hazardous asteroids. It would cost $1.1 billion
to build a new space telescope for the same purpose. Congress has
rejected both of these plans because they are "too costly (Shoemaker)."
Using existing systems, we have detected thousands of NEOs in our solar
system. They range in size from a few hundred meters to several
kilometers, the largest being the celestial body Ganymed, which is over
32 km, or 20 miles, in diameter (Near Earth Object Fact Sheet).
Although it is highly unlikely, if the asteroid Ganymed hit our planet
it would obliterate all life, shred the earth's crust, and bury itself
deep in the mantle. It would cause massive volcanic eruptions,
earthquakes, and even has a chance of ripping our planet apart.
There are over 20,000 objects with diameters greater than 140
meters, or 460 feet, that could collide with the earth. NASA scientists
believe they could locate 90% of the objects by the year 2020, but
funding has prevented them from doing their job (Near Earth Objects).
A perfect example would be the near-miss of the asteroid 2002 EM7,
which missed our planet by 298,400 miles, which is about 1.2 times the
distance from earth to the moon (Britt).
The object was between 40 and 80 meters across, or 130 to 260 feet, and
could have destroyed an entire city if it had impacted earth. Some
people think that our current system is sufficient, but here's the
kicker; scientists didn't find the object days after it had passed by
our planet. How can the current system be adequate when it didn't
detect an object that could have slammed into our planet and killed
millions of people?
The asteroid came at earth from a blind spot in which it couldn't
have been detected using current systems (Britt). The solution to
correcting this blind spot would be to construct an observatory or to
launch a space-based platform that can observe asteroids from a
different galactic vantage point. Scientists at NASA have suggested
that placing an observatory around the planet Mercury could help detect
objects in this blind spot, but the funding has certainly not been made
available by Washington (Britt).
On November 1st, 2007 an object 50 meters across passed within 5
million miles of earth and wasn't detected until November 20th. An
article on NASA's NEO website highlighted the event,
"Designated 2007 WD5, the asteroid was discovered on Nov. 20, 2007
by the NASA-funded Catalina Sky Survey using a 1.5m telescope on Mt.
Lemmon, near Tucson. The object had already passed within 7.5 million
km (5 million miles) of the Earth on Nov. 1, before it was discovered. (Chesley)."
Right now, this is a common occurrence. The lack of funding
by Congress leaves us opens to an impact which could change the course
of human history, or completely wipe us out as a species. Without a
comprehensive program to detect objects of all sizes and trajectories,
we leave ourselves open to a knockout blow.
An article on Space.com explains that, "about 1,000 asteroids larger
than 1 kilometer (0.6 miles) are thought to lurk in orbits that might
one day threaten Earth," and that "about 500 of them have been found (Britt)."
The larger objects are easier to track and locate, but pose a greater
threat to civilization. Smaller objects are harder to track, but could
still cause localized devastation. Over Siberia in 1908, an unknown
object exploded, likely an air-burst meteor, and flattened over 800
miles of trees and vegetation. The size of the object which exploded is
unknown, but measurements and estimates place the size around 60 to 80
meters across (Research Center). The
object caused widespread devastation, and if it had exploded over a
major city it would have caused hundreds of thousands, if not millions
of deaths. Objects this small are much more difficult to detect than
larger objects, even today.
The size of the object is not the only thing that determines the
magnitude of impact; density is also a factor. A smaller asteroid, like
the 20 meter wide asteroid that left a 600 foot deep crater in Arizona,
can cause as much damage as a larger asteroid with a lower density (Britt).
The diameter doesn't necessarily tell the whole story. Objects larger
than 500 meters across can cause widespread surface damage to the earth
wherever they impact, create tsunamis, block out the sun, incinerate
large areas, and kill millions of people. The larger the object, the
greater the threat they pose.
As of now, the greater risk comes from the smaller asteroids which are harder to detect with our current systems. Until
we develop a full catalogue of the larger asteroids, and we've detected
and tracked every one, we are susceptible to a catastrophic impact, no
matter how small the chance. The problem isn't warding off asteroids,
because we have adequate weapons like nuclear ballistic missiles that
can change an asteroid's course, but it is detecting them. Right now we
aren't allocating enough resources to provide NEO researchers the tools
to evaluate all potential threats.
To solve the problem of under funding by congress, I propose an
ambitious presentation. Recently, the University of Arizona published a
web page which allows users to 'test' their own asteroid impact. You
can input projectile diameter, velocity, type of material, density,
impact angle, and rock target type and you will receive a series of
outputs which predict an asteroid impact (Marcus).
My proposal involves a much more graphical approach, as opposed to a
strictly numerical approach, but would incorporate the use of genuine
data like the University of Arizona's website.
I think that the members of congress need to see visual
representations of what an impact would mean for the earth. They need
to see 3d models of an asteroid slamming into an American city. They
need to understand how real the threat of an impact is. Rather
than just a bunch of numbers and statistics, they need to see that
cities will be obliterated, people will die, and the world will be
changed forever by a significant or well-placed impact. I would provide
graphs of damage costs, death tolls, and would show what various
impacts would do to cities, shorelines, climate, and the stability of
life on earth. I think that too often politicians look at problems
based on numbers, and fail to see the reality of some situations.
The project will graphically explain what different size asteroids
would do to urban areas, suburban areas, and rural areas. The
presentation would mainly use smaller asteroids from 30 to 500 meters
across as examples. It is simply more realistic and I wouldn't want to
go overboard and lose credibility by proclaiming a giant asteroid,
which we wouldn't be able to detect, would unknowingly slam into our
world unexpectedly. Realism and graphical representation are key to
convincing lawmakers to fund NEO programs. Data from actual past-earth
impacts would be plugged-in to the simulation, and the result would be
an accurate depiction of what might happen. I would also utilize photos
of impact craters in Arizona, the Yucatan in Mexico, Siberia, and Asia,
as well as craters on the moon and Mars, to quantify the threat. I
think that after seeing the consequences of an impact on American
cities, and seeing the evidence of past impacts, it would be incredibly
hard to look away.
Over the course of human history, our species has faced many
threats. Some came from predators in the wild, some from other humans,
and some from space. Our ancestors were powerless to stop an incoming
asteroid from striking the planet. If a 'World-Killer' asteroid had
slammed into the planet, they wouldn't see it coming, and couldn't do
anything about it. Now, for the first time in our history, we have the
ability to prevent our own demise. We can detect and deflect incoming
objects, saving millions of lives, and possibly our planet. Out there
in the blackness of space, an asteroid large enough to cram the city of
Phoenix hundreds of feet into the earth's mantle slowly tumbles over
itself. It's in one of our blind spots, where we can't detect it. If we
invest a few billion dollars in NEO programs, we can greatly reduce the
possibility of being hit by surprise.
The question is: Why aren't we? The
graveness of the situation needs to be appreciated by our lawmakers, as
well as the public. No longer can we sit by and fund wars oblivious to
the real and immense threat posed by asteroids. Write your
politicians, protest in Washington, do whatever it takes for them to
listen. We might not have as much time as you think, and don't let
politicians tell you otherwise. They're quick to fund wars, yet quick
to ignore what really matters.
Tom Spears
The Ottawa Citizen
Thu, 01 May 2008 12:00 EDT
Canada is preparing to launch the first space mission ever to search
for asteroids between Earth and the sun - the type of asteroid most
likely to slam into our planet.
Fittingly for this country, the Near Earth Object Surveillance
Satellite is not a Hubble-sized monster. It's a 60-kilogram
microsatellite, costing a mere $10 million (including the pricetag for
launch) yet able to deliver science results never seen before.
NEOSSat will search for asteroids that are closer to the sun than
Earth. These are nearly impossible to see from our planet's surface -
there's too much atmosphere and sunshine - but easier to spot from
space.
The suitcase-sized satellite is expected to launch in two years.
"This is the first space-based asteroid-searching telescope, period
... Why shouldn't Canada be the leader in a field? And it happens in
this case, we are," says Alan Hildebrand of the University of Calgary,
one of two principal scientists for the satellite.
Canada's specialty is in shrinking the equipment that holds a
satellite stable in space, which allows a very small satellite to aim a
telescope without having its aim wobble. "It happens that we're the
world leaders in this technology," he added. Instead of launching an
11-tonne Hubble, Canada can send up a 60-kilogram "microsatellite."
Astronomers have been watching asteroids for many years. Most are
located in a belt on the far side of Mars, but others are scattered
here and there through the solar system. Most of the ones we know are
outside Earth's orbit.
"Most people are interested in the possibility that an asteroid may impact the Earth," he said.
"What you can do from the space that you can't do from Earth is, if
you have a baffle (to block sunlight), you can look close to the sun."
Asteroids from far out in the solar system sometimes swing past
Earth, but they don't stay long. The ones between us and the sun hang
around our neighbourhood permanently. And the most dangerous of these
have an orbit that crosses ours at times.
As well, some of these asteroids match Earth's own speed fairly closely, making it relatively easy to fly to one and land there.
"I think the most exciting thing about this mission is we are going
to find asteroids that are accessible from our planet," Mr. Hildebrand
said. "So I see it as leveraging other exploration, both manned and
unmanned," to land on asteroids.
"We've been to the moon. There's always more you can do (there), but
asteroids have so much more to teach us about the origins of the solar
system."
Many asteroids are leftovers from the original material of the solar
system, unlike the moon, which has evolved over time. And some have
water and other materials of interest. As well, their weak gravity
makes it easier to land, and escape again, than the moon and Mars allow.
No one has ever done a systematic survey for asteroids inside
Earth's orbit. Estimates say there could be about 50 big ones (more
than a kilometre wide), and perhaps thousands of little ones.
In a second mission, NEOSSat will also track the paths of other
satellites in very high orbits. NEOSSat is based on the design of MOST,
a hugely successful - and very small - Canadian satellite launched in
2003 that's looking at stars right now. MOST and NEOSSat are both
flying telescopes, mini-versions of the 11-tonne Hubble.
The new satellite will look on an angle about 45 degrees away from
the sun, looking for objects that move from one photo to the next.
The mission a partnership of agencies led by the Canadian Space
Agency and Defence Research and Development Canada. Brad Wallace is the
lead scientist at Defence R&D Canada. The prime contractor is
Dynacon Inc.
"It's a new paradigm for doing science from space. You don't have to
put up hundreds of millions ... or billions of dollars' worth of
hardware," says astronomer Peter Brown of the University of Western
Ontario, a member of the science team for the new satellite. "You can
start doing things in smaller packages with smaller electronics."
Canada space mission targets asteroids
Tom Spears
Canwest News Service
Fri, 02 May 2008 23:55 EDT
Canada is preparing to launch the first space mission ever to search
for asteroids between Earth and the sun -- the type of asteroid most
likely to slam into our planet.
 |
| ©Unknown |
Fittingly for this country, the Near Earth Object Surveillance
Satellite is not a Hubble-sized monster. It's a 60-kilogram
microsatellite, costing a mere $10 million, yet able to deliver science
results never seen before.
NEOSSat will search for asteroids that are closer to the sun than
Earth. These are nearly impossible to see from our planet's surface --
there's too much atmosphere and sunshine -- but easier to spot from
space.
The suitcase-sized satellite is expected to launch in two years.
"This is the first space-based asteroid-searching telescope, period
. . . Why shouldn't Canada be the leader in a field? And it happens in
this case, we are," says Alan Hildebrand of the University of Calgary,
one of two principal scientists for the satellite.
Canada's specialty is in shrinking the equipment that holds a
satellite stable in space, which allows a very small satellite to aim a
telescope without having its aim wobble.
"It happens that we're the world leaders in this technology," he added.
Instead of launching an 11-tonne Hubble, Canada can send up a 60-kilogram "microsatellite."
Astronomers have been watching asteroids for many years. Most are
located in a belt on the far side of Mars, but others are scattered
here and there through the solar system. Most of the ones we know are
outside Earth's orbit.
"Most people are interested in the possibility that an asteroid may impact the Earth," Hildebrand said.
"What you can do from the space that you can't do from Earth is, if
you have a baffle (to block sunlight), you can look close to the sun."
Asteroids from far out in the solar system sometimes swing past
Earth, but they don't stay long. The ones between us and the sun hang
around our neighbourhood permanently. And the most dangerous of these
have an orbit that crosses ours at times.
As well, some of these asteroids match Earth's own speed fairly closely, making it relatively easy to fly to one and land there.
"I think the most exciting thing about this mission is we are going
to find asteroids that are accessible from our planet," Hildebrand said.
"So I see it as leveraging other exploration, both manned and unmanned," to land on asteroids.
"We've been to the moon. There's always more you can do (there), but
asteroids have so much more to teach us about the origins of the solar
system."
Many asteroids are leftovers from the original material of the solar
system, unlike the moon, which has evolved over time. And some have
water and other materials of interest. As well, their weak gravity
makes it easier to land, and escape again, than the moon and Mars allow.
No one has ever done a systematic survey for asteroids inside
Earth's orbit. Estimates say there could be about 50 big ones -- more
than a kilometre wide -- and perhaps thousands of little ones.
The mission is a partnership of agencies led by the Canadian Space Agency and Defence Research and Development Canada.
The eta Aquarid meteor shower peaks
Space Weather
Sun, 04 May 2008 18:48 EDT
The eta Aquarid meteor shower peaks this year
on Monday, May 5th, and Tuesday, May 6th. The best time to look, no
matter where you live, is during the hours immediately before sunrise.
If you can, get away from city lights; you will see more meteors from
the dark countryside.
2008 should be a good year for the eta Aquarid meteors. The Moon is
new, which means no lunar glare, and Earth is expected to pass through
an unusually dense region of comet dust, driving meteor rates as high
as 70 per hour in the southern hemisphere. Sky watchers in Australia,
New Zealand, South America and southern Africa are favored. It is
possible to see the shower from the northern hemisphere, too, but rates
are reduced to less than 30 per hour.
The eta Aquarids are flakes of dust from Halley's Comet, which last visited Earth in 1986. Although the comet is now far away,
beyond the orbit of Uranus, it left behind a stream of dust. Earth
passes through the stream twice a year in May and October. In May we
have the eta Aquarid meteor shower, in October the Orionids. Both are
caused by Halley's Comet.
The eta Aquarids are named after a 4th-magnitude star in the
constellation Aquarius. The star has nothing to do with the meteor
shower except that, coincidentally, meteors appear to emerge from a
point nearby. Eta Aquarii is 156 light years from Earth and 44 times
more luminous than the Sun.
The constellation Aquarius does not rise very far above the horizon
in the northern hemisphere, and that's why northerners see relatively
few meteors. But the ones they do see could be spectacular
Earthgrazers.
Sky maps: Northern Hemisphere | Southern Hemisphere
Earthgrazers are meteors that skim horizontally through the upper
atmosphere. They are slow and dramatic, streaking far across the sky.
The best time to look for Earthgrazers is between 2:00 to 2:30 a.m.
local time when Aquarius is just peeking above the horizon.
Experienced meteor watchers suggest the following viewing strategy:
Dress warmly. Bring a reclining chair, or spread a thick blanket over a
flat spot of ground. Lie down and look up somewhat toward the east.
Meteors can appear in any part of the sky, although their trails will
point back toward Aquarius.
Tidbits:
* Eta Aquarid meteoroids hit Earth's atmosphere traveling 66 km/s.
* Typical eta Aquarid meteors are as bright as a 3rd magnitude star.
Asteroid Impact 65 Million Years Ago Triggered A Global Hail Of Carbon Beads
ScienceDaily
Mon, 05 May 2008 20:10 EDT
 |
| ©Mark Harvey |
| Carbon
cenospheres are tiny, carbon-rich particles that form when coal and heavy fuel are heated intensely. Scientists have now learned that cenospheres can form in the wake of asteroid impacts, too. |
The asteroid presumed to have wiped out the dinosaurs struck the
Earth with such force that carbon deep in the Earth's crust liquefied,
rocketed skyward, and formed tiny airborne beads that blanketed the
planet, say scientists from the U.S., U.K., Italy, and New Zealand in
this month's Geology.
The beads, known to geologists as carbon cenospheres, cannot be
formed through the combustion of plant matter, contradicting a
hypothesis that the cenospheres are the charred remains of an Earth on
fire. If confirmed, the discovery suggests environmental circumstances
accompanying the 65-million-year-old extinction event were slightly
less dramatic than previously thought.
"Carbon embedded in the rocks was vaporized by the impact,
eventually forming new carbon structures in the atmosphere," said
Indiana University Bloomington geologist Simon Brassell, study coauthor
and former adviser to the paper's lead author, Mark Harvey.
The carbon cenospheres were deposited 65 million years ago next to a
thin layer of the element iridium -- an element more likely to be found
in Solar System asteroids than in the Earth's crust. The iridium-laden
dust is believed to be the shattered remains of the 200-km-wide
asteroid's impact. Like the iridium layer, the carbon cenospheres are
apparently common. They've been found in Canada, Spain, Denmark and New
Zealand.
But the cenospheres' origin presented a double mystery. The
cenospheres had been known to geologists only as a sign of modern times
-- they form during the intense combustion of coal and crude oil.
Equally baffling, there were no power plants burning coal or crude oil
65 million years ago, and natural burial processes affecting organic
matter from even older ages -- such as coals from the
300-million-year-old Carboniferous Period -- had simply not been cooked
long or hot enough.
"Carbon cenospheres are a classic indicator of industrial activity,"
Harvey said. "The first appearance of the carbon cenospheres defines
the onset of the industrial revolution."
The scientists concluded the cenospheres could have been created by
a new process, the violent pulverization of the Earth's carbon-rich
crust.
Geologists do believe the Earth burned in spots as molten rock and
super-hot ash fell out of the sky and onto flammable plant matter. But
the charcoal-ized products of these fires only appear in some places on
Earth, and are more often found near the asteroid impact site of
Chicxulub Crater, just west of Mexico's Yucatan Peninsula. Some
geologists had thought all carbon particles resulting from the impact
was ash from global scale forest fires, but the present research
strongly contradicts that assumption.
The scientists examined rock samples from eight marine locations in
New Zealand, Italy, Denmark and Spain. They also examined carbon-rich
particles from five non-marine locations in the U.S. and Canada.
Following chemical and microscopic analysis, the researchers concluded
the particles were carbon cenospheres, similar to the ones produced by
industrial combustion.
The scientists also found that the farther the sample site was from
the Chicxulub Crater, the smaller the cenospheres tended to be. That
observation is consistent with the expectation that particles were
produced by the asteroid impact, since once the particles are ejected,
heavier particles should fall back to Earth sooner (and travel shorter
distances) than lighter particles.
Last, the scientists estimated the total mass of carbon cenospheres
ejected by the asteroid collision, assuming a global distribution, to
be perhaps as much as 900 quadrillion kilograms. Whether or not the
carbon cenospheres are truly ubiquitous, however, needs further
corroboration.
"There are still clues to unravel about the events occurring around
the time of the impact," Brassell said. "And there are aspects of the
Earth's natural carbon cycle that we didn't previously consider."
Harvey is interested in the unique properties of the cenospheres
themselves. "Perhaps we can generate and study carbon cenospheres to
better understand them," he said. "We also need to look for the
cenospheres in other parts of the world and also around the time of
other extinction events."
Harvey conducted the research while he was a master's student at IU
Bloomington. He is now a geoscientist for Sinclair Knight Merz in New
Zealand. Claire Belcher (University of London) and Alessandro Montanari
(Coldigioco Geological Observatory) also contributed to the study. It
was funded by the Geological Society of America, the Indiana University
Department of Geological Sciences, and the Society for Organic
Petrology.
65-million-year-old asteroid impact triggered a global hail of carbon beads
Indiana University
Mon, 05 May 2008 14:25 EDT
The asteroid presumed to have wiped out the dinosaurs struck the
Earth with such force that carbon deep in the Earth's crust liquefied,
rocketed skyward, and formed tiny airborne beads that blanketed the
planet, say scientists from the U.S., U.K., Italy, and New Zealand in
this month's Geology.
The beads, known to geologists as carbon cenospheres, cannot be
formed through the combustion of plant matter, contradicting a
hypothesis that the cenospheres are the charred remains of an Earth on
fire. If confirmed, the discovery suggests environmental circumstances
accompanying the 65-million-year-old extinction event were slightly
less dramatic than previously thought.
"Carbon embedded in the rocks was vaporized by the impact,
eventually forming new carbon structures in the atmosphere," said
Indiana University Bloomington geologist Simon Brassell, study coauthor
and former adviser to the paper's lead author, Mark Harvey.
 |
| ©Mark Harvey |
| Carbon
cenospheres are tiny, carbon-rich particles that form when coal and heavy fuel are heated intensely. Scientists have now learned that cenospheres can form in the wake of asteroid impacts, too. |
The carbon cenospheres were deposited 65 million years ago next to a
thin layer of the element iridium -- an element more likely to be found
in Solar System asteroids than in the Earth's crust. The iridium-laden
dust is believed to be the shattered remains of the 200-km-wide
asteroid's impact. Like the iridium layer, the carbon cenospheres are
apparently common. They've been found in Canada, Spain, Denmark and New
Zealand.
But the cenospheres' origin presented a double mystery. The
cenospheres had been known to geologists only as a sign of modern times
-- they form during the intense combustion of coal and crude oil.
Equally baffling, there were no power plants burning coal or crude oil
65 million years ago, and natural burial processes affecting organic
matter from even older ages -- such as coals from the
300-million-year-old Carboniferous Period -- had simply not been cooked
long or hot enough.
"Carbon cenospheres are a classic indicator of industrial activity,"
Harvey said. "The first appearance of the carbon cenospheres defines
the onset of the industrial revolution."
The scientists concluded the cenospheres could have been created by
a new process, the violent pulverization of the Earth's carbon-rich
crust.
Geologists do believe the Earth burned in spots as molten rock and
super-hot ash fell out of the sky and onto flammable plant matter. But
the charcoal-ized products of these fires only appear in some places on
Earth, and are more often found near the asteroid impact site of
Chicxulub Crater, just west of Mexico's Yucatan Peninsula. Some
geologists had thought all carbon particles resulting from the impact
was ash from global scale forest fires, but the present research
strongly contradicts that assumption.
The scientists examined rock samples from eight marine locations in
New Zealand, Italy, Denmark and Spain. They also examined carbon-rich
particles from five non-marine locations in the U.S. and Canada.
Following chemical and microscopic analysis, the researchers concluded
the particles were carbon cenospheres, similar to the ones produced by
industrial combustion.
The scientists also found that the farther the sample site was from
the Chicxulub Crater, the smaller the cenospheres tended to be. That
observation is consistent with the expectation that particles were
produced by the asteroid impact, since once the particles are ejected,
heavier particles should fall back to Earth sooner (and travel shorter
distances) than lighter particles.
Last, the scientists estimated the total mass of carbon cenospheres
ejected by the asteroid collision, assuming a global distribution, to
be perhaps as much as 900 quadrillion kilograms. Whether or not the
carbon cenospheres are truly ubiquitous, however, needs further
corroboration.
"There are still clues to unravel about the events occurring around
the time of the impact," Brassell said. "And there are aspects of the
Earth's natural carbon cycle that we didn't previously consider."
Harvey is interested in the unique properties of the cenospheres
themselves. "Perhaps we can generate and study carbon cenospheres to
better understand them," he said. "We also need to look for the
cenospheres in other parts of the world and also around the time of
other extinction events."
Nasa plans landing on 40m-wide asteroid travelling at 28,000mph
Ian Sample
Guardian
Wed, 07 May 2008 15:10 EDT
· US eyes 2000SG344 for Armageddon-type mission
· Rock seen as stepping stone to deep space
It was once considered the most dangerous object in the universe,
heading for Earth with the explosive power of 84 Hiroshimas. Now an
asteroid called 2000SG344, a lump of rock barely the size of a large
yacht, is in the spotlight again, this time as a contender for the next
giant leap for mankind.
 |
| ©Science Photo Library / Guardian |
| Initial
calculations showed that there was a chance that the asteroid Apophis would strike Earth at its close approach on April 13 2029. |
Nasa engineers have identified the 1.1m tonne asteroid, which in
2000 was given a significant chance of slamming into Earth, as a
potential landing site for astronauts, ahead of the Bush
administration's plans to venture deeper into the solar system with a
crewed voyage to Mars.
The mission - the first to what officials call a Near Earth Object
(NEO) - is being floated within the US space agency as a crucial
stepping stone to future space exploration.
A report seen by the Guardian notes that by sending
astronauts on a three-month journey to the hurtling asteroid,
scientists believe they would learn more about the psychological
effects of long-term missions and the risks of working in deep space,
and it would allow astronauts to test kits to convert subsurface ice
into drinking water, breathable oxygen and even hydrogen to top up
rocket fuel. All of which would be invaluable before embarking on a
two-year expedition to Mars.
Under the Bush administration, Nasa has been charged with sending
astronauts back to the moon, beginning in 2020 and culminating in a
permanent lunar outpost, itself a jumping off point for more distant
Mars missions. With the agency's ageing fleet of space shuttles due to
be retired soon after 2010, the agency has begun work on a replacement
called Orion and a series of Ares rockets that will blast them into
orbit.
In a study due to be published next month, engineers at Nasa's
Johnson Space Centre in Houston and Ames Research Centre in California
flesh out plans to use Orion for a three to six month round-trip to the
asteroid, with astronauts spending a week or two on the rock's surface.
As well as giving space officials a taste of more complex missions,
samples taken from the rock could help scientists understand more about
the birth of the solar system and how best to defend against asteroids
that veer into Earth's path.
"An asteroid will one day be on a collision course with Earth.
Doesn't it make sense, after going to the moon, to start learning more
about them? Our study shows it makes perfect sense to do this soon
after going back to the moon," said Rob Landis, an engineer at Johnson
Space Centre and co-author of the report, which is due to be published
in the journal Acta Astronautica.
More precise measurements of the orbit of 2000SG344 have allayed
fears that it could hit Earth sometime around the end of September
2030, but the asteroid is still expected to come close in astronomical
terms.
The report lays out plans for a crew of two to rendezvous with a
speeding asteroid that is due to pass close by Earth. After a
seven-week outward journey, the Orion capsule would swing around and
close in on the rock.
Because gravity is close to zero on asteroids, the capsule would
need to attach itself, possibly by firing anchors into the surface. For
the same reason, astronauts would not be able to walk around on the
surface as they did on the moon. "On some of these asteroids, you could
jump up and go into orbit, or maybe even leave for good," said Landis.
A round trip to an asteroid could be done with less fuel than a moon
mission, but is technically very challenging. The asteroid is only 40
metres across and spins as it hurtles through space at 28,000mph.
Landis thinks that a trip to an asteroid could capture imaginations
even more than a return to our nearest celestial neighbour. "When we
head back to the moon, I think we'll see many of the same scenes we saw
in the 60s and 70s Apollo programme. We've been to the moon, we got
that T-shirt back in 1969. But whenever we've sent robotic probes to
look at asteroids, we've always been surprised at what we've seen," he
said.
Because asteroids were forged in the earliest days of the solar
system, analysing samples from them could shed light on the conditions
that prevailed when the Earth was formed.
"Near Earth objects are a potential collision hazard to Earth and it
may one day be necessary to deflect an asteroid from a collision course
with Earth," said Ian Crawford, a planetary scientist at Birkbeck
College, London. "Having the capability in your back pocket to deflect
an asteroid might be a good insurance policy for the future, and for
that, you want to know what they are made of, how to rendezvous with
them, and whether you risk getting hit by debris if you fire something
at it."
New York State: NEADS says loud noise could have been a sonic boom
wktv.com
Wed, 07 May 2008 17:13 EDT
We've had lots of phone calls into the newsroom today about a loud
booming sound this afternoon. Some viewers even felt their homes
shaking.
North East Air Defense Sector officials say there was plenty of air
traffic today, and the sound could have been a sonic boom. But that is
not confirmed.
Canada to launch asteroid-hunting satellite
Thetechherald.com
Thu, 08 May 2008 19:24 EDT
 |
| ©CSA |
| The CSA is to launch a suitcase-sized satellite to detect Near Earth Objects. |
A team led by the Canadian Space Agency is set to launch a microsatellite designed to detect near-Earth asteroids from space.
The 60-kilogram, $10 million, Near Earth Object Surveillance
Satellite (NEOSSat) will search for asteroids between the Earth and
Sun, the ones most likely to pose a danger to our planet.
More than 5000 such objects have been found with orbits that would make them a risk of collision with the Earth.
The suitcase-sized satellite will be in a unique position to spot
any danger from the asteroids which are often difficult to detect from
Earth-based observatories.
"This is the first space-based asteroid-searching telescope, period," said Alan Hildebrand of the University of Calgary, one of two principal scientists for the satellite to reporters.
"It happens that we're the world leaders in this technology," he added.
Hildebrand said the mission also was the basis of further asteroid research.
"I think the most exciting thing about this mission is we are going
to find asteroids that are accessible from our planet," Hildebrand
said."So I see it as leveraging other exploration, both manned and
unmanned," to land on asteroids, reported Canada.com.
"We've been to the moon. There's always more you can do (there), but
asteroids have so much more to teach us about the origins of the solar
system," he said.
"NEOSSAT may indeed contribute to our knowledge of extremely
interior asteroids, and in that light I look forward to what it may
find," said Alan Harris of the Space Science Institute in Boulder Colorado, US to the New Scientist.
The satellite will rely on a telescope with a 15-centimetre mirror, similar to that used by amateur astronomers.
It is expected to be launched in two years time.
Comets might have caused ancient American extinctions 13,000 years ago
WebIndia123.com
Thu, 08 May 2008 05:53 EDT
Scientists have come up with a controversial theory which suggests
that huge comet impacts wiped out North America's large mammals 13,000
years ago.
According to a report in National Geographic News, the hypothesis,
first presented in May 2007, proposes that an onslaught of
extraterrestrial bodies caused the mass extinction known as the
"Younger Dryas event" and triggered a period of climatic cooling.
Around this time, large mammals including mammoths, mastodons,
horses, camels, and saber-toothed cats went extinct in North America.
James Kennett, a geologist at the University of California, Santa
Barbara, is one of the main proponents of the comet-impact hypothesis.
He said the theory is consistent in explaining and linking these various phenomena.
"We suggest it's a series of aerial bursts, more of a multiple
Tunguska event, like a shotgun," he said, referring to the explosion of
an extraterrestrial object over Siberia in 1908.
"This would also explain evidence of fires across swaths of North America," he added.
He and his colleagues have also found widespread and abundant
minuscule diamonds and magnetic particles in the layer of Earth that
dates to this time.
These features were formed in the extremely hot and high-pressure
environment created by the series of explosions, Kennett suggested.
"It's obviously an outrageous hypothesis; in the sense that
it wasn't predicted. It has come out of left field," said Kennett. "But
all I can say is that I don't know of any other process that can
account for the wide display of data that we have and continue to
generate other than some kind of an extraterrestrial impact," he added.
But the theory has been debated widely since it was introduced.
Stuart Fiedel from the Louis Berger Group, a private archaeological
firm in Richmond, Virginia, argued that the theory fails to address
some major questions-like how comet blasts could have wiped out woolly
mammoths and saber-toothed cats in North America, while leaving humans
unscathed.
"If this impact was powerful enough to fricassee mammoths and
mastodons and short-faced bears and other big fauna that were on the
landscape, you would think that it would have decimated the human
population as well-not only by direct thermal shock but by wiping out
much of their food source," he said.
"So you should have a marked fall-off or termination of human populations, and we don't see that," he added.
In spite the debate, experts agree that Earth got a shock to its system 12,900 years ago.
The world was in the middle of thawing out from the last ice age,
when the "Younger Dryas event" inexplicably plunged it back into near
glacial temperatures. This anomalous period lasted for about 1,300
years.
Cloudbait Observatory
Thu, 24 Apr 2008 23:54 EDT
This very bright fireball occurred over
Colorado's Western Slope at 11:51 PM MDT, April 24th. One witness north
of Montrose reported a bright, bluish white object showing at least two
distinct fronts as well as a persistent trail.
 |
| ©Cloudbait |
The image is from the Montrose camera. It was also recorded by the Cloudbait camera.
The meteor appears to have begun about 18 miles west of Montrose,
and ended about 10 miles northwest of Olathe. Any meteorites that might
have been produced would probably be found on one of the mesas west or
southwest of Olathe.
Comment: For videos of the increasing number of fireballs over Colorado, captured by Cloudbait Observatory, go here.
High School freshman unearths asteroid, cometary evidence for mammoth extinction
Peter Johnson
Great Falls Tribune
Thu, 01 May 2008 14:16 EDT
After working countless hours digging soil samples and analyzing
them with sophisticated microscopes, Great Falls High School freshman
Katelyn Gibbs has come up with evidence that a comet or meteorite
crashed to Earth in Montana 13,000 years ago and had major impact on
animals living here at the time.
"Bing! She nailed it!" said David Baker of Monarch, a veteran earth
science research scientist who mentored Gibbs on the project. "Katelyn
found definitive proof - nanodiamonds and iron micrometeorites - for
the extraterrestrial impact event that killed the mammoths in Montana.
"She is making discovery after discovery; she's an incredible kid," Baker said.
All that from a 15-year-old student who decided to put a little extra time into a science fair topic.
Jonathan Logan, her Great Falls High science teacher, said he often
has to prod students into doing science fair projects and help them
along the way.
Not Gibbs.
"She is a very self-directed student who spends lots of time on her
regular classes and then two or three hours a night on her science fair
project," Logan said. "She watched a TV show and read a book about how
extraterrestrial events changed the course of animals, and now she's
writing her own Montana chapter."
Gibbs said she watched a National Geographic TV special last year
called "Mammoth Mystery" that showed research elsewhere in North
America that an extraterrestrial impact event - a comet or meteorite
hitting with huge force - caused the large hairy beasts to die.
"I was hooked and wanted to find out if there was any evidence that such events happened in Montana," she said.
She read Arizona expert Allan West's book, "Cycle of Cosmic Catastrophe," and talked to Logan and Baker about it.
Katelyn, who wants to become an aerospace scientist and possibly an
astronaut for NASA, had impressed Baker when he judged her previous
year's science fair entry, "Protecting Astronauts from Galactic Cosmic
Rays."
"Dr. Baker pointed the finger generally on what sites she should
look for, but Katelyn swung into action," recalled her mother, Celeste
Gibbs, a pre-school teacher.
"Neither my husband, Richard, a supervisor at AvMax, nor I had been
keenly interested in science, so it's been quite a challenge for us to
keep up with her.
"There was a stretch of several months where we went out nearly
every weekend to cover the hills of Montana to find sites in the right
geological layer and time. Katelyn did all the digging and climbing
into an exposed gorge. We were her mule pack, driving and carrying
shovels and a ladder. Katelyn learned how to use all kinds of
microscopes and a special type of Geiger counter."
Essentially, Gibbs followed Baker's suggestions, including where to
look and what to look for. She worked for hours to find rusty brown
soil samples in a particular geological layer at three different sites
whose age had been determined to be from 13,000 years ago, the period
when mammoths became extinct.
She was allowed access to one site on the Rocky Mountain Front near Augusta where mammoth fossils had been discovered.
Other successful sites were at a Hutterite colony near Choteau and a geological dig by Townsend.
She took extensive soil samples and put them in water to see if they
floated, which would indicate they contained carbon, Gibbs explained.
If they still floated when she examined them under a microscope, it
meant they were carbon glass spherules - tiny gray solidified droplets.
Finally, she sent those samples to West, the Arizona scientist and
author, who examined them with a powerful transmission electronic
microscope. He determined she had found nanodiamonds, tiny, shiny
particles formed at ultra-high temperatures, such as when a comet or
meteorite crashes through the Earth's atmosphere.
She also found iron micrometeorites and radioactive particles that
Baker said are all proof that an extraterrestrial impact event -
probably a comet hitting - occurred in Montana 13,000 years ago.
Furthermore, Gibbs found iron micrometeorites embedded in the tusk
of the mammoth, further linking the animal's possible extinction to the
comet striking.
Baker goes even further, noting that the Clovis Culture of
Paleo-Indian people had lived in Montana about the same time and
depended on mammoths for food. Evidence of their culture seemed to
abruptly terminate when the mammoths disappeared, he said.
"I was so excited to be the first in Montana to find this kind of evidence," Gibbs said.
Parents and even judges at science fairs sometimes scratched their
heads at the extensive and complex explanations on Gibbs' science fair
project.
"When they read about extraterrestrial impact events, they think I'm
talking about aliens or ET arriving," she chuckled. The word simply
means "something coming from outside the earth's limits." She's been
looking for something that would crash at high speed and explode.
For example, the micrometeorites are so hot that they form fusion
crusts and flow lines that can be viewed under a microscope, she said.
In fact, Gibbs, her teacher Logan and mentor Baker all noted that
her findings were all microscopic, explaining why they were so hard to
find.
Baker put it in hard-to-fathom scientific terms: "A nanodiamond is approximately 5 to 10 millionth of a millimeter in diameter."
Gibbs' mother Celeste used more understandable terms: "It takes
30,000 nanodiamonds laid side by side to equal the width of a human
hair."
Gibbs did well at the Montana state science fair last month in
Missoula, winning several awards and placing third runner-up for the
grand award.
She will show her project at the Intel International Science and Engineering Fair in Atlanta on May 11-16.
In the meantime, she said she wasn't a bit nervous giving talks to
two Montana science groups. "Katelyn gave a 20-minute presentation to
the Montana Archeological Society in Billings last month and had 60
professional archeologists in the palm of her hands," Baker said.
Flashback:
Comets, dragons & prophets of doom
Bill Napier
Frontiers
Tue, 12 May 1998 16:50 EDT
Ancient myths suggest that a giant comet may have visited the Earth a few thousand years ago, raining fireballs and meteors
Scientists are starting to recognise that the evolution of life on
Earth has been affected, if not largely shaped, by its celestial
environment. We now recognise that throughout its history the Earth has
been bombarded by comets, small asteroids, meteorites (small rocky or
iron bodies) and smaller particle and dust (meteor) showers. Over the
years, astronomers have detected a substantial population of such small
bodies out there in the Solar System, confirming that the threat of
their impact with the Earth is a significant one. Current estimates,
for example, suggest that between 10 and 30 impacts similar to the one
that occurred in Tunguska in Siberia in 1908 have happened over
recorded history, with perhaps one or more exploding with a force
equivalent to that produced by 500 to 1000 megatonnes of TNT.
 |
| ©Frontiers |
| A mediæval representation of a meteorite fall as a serpent in the sky |
The potential hazards vary in size - from asteroids less than a
kilometre wide to comets several hundred kilometres across. There is no
known upper limit to the size of comets. In assessing current and
near-future risks, we must therefore pay attention to the rare, giant
comets that enter short-period, Earth-crossing orbits on timescales of
100,000 years. Such comets, which are made of a mixture of ice and
dust, disintegrate as they approach the Sun. As they do, they generate
a dense swarm of meteors which may include short-lived concentrations
of dust along with streams of sub-kilometre bodies. These
concentrations spread out along the orbit of the comet and are
generally invisible except when the Earth intercepts the track and the
particles manifest themselves as shooting stars. With the Infrared
Astronomical Satellite IRAS, however, which operated in the 1980s, such
trails of material were also detected in the infrared, one of them
following Comet Encke - a short-period comet (orbital period 3.3 years)
first observed in 1786.
If a giant comet were thrown into a short-period, Earth-crossing
orbit, its disintegration under the effect of sunlight would release a
copious amount of dust into the inner planetary system. Ploughing
through such dust, the Earth would acquire a reflective blanket and
cool by up to about 5 degrees, possibly sliding into a new ice age.
Even after this phase, brief, sharp climatic coolings would be expected
during epochs when the Earth passed annually through the comet's meteor
stream. Precession of the cometary orbit, analogous to the slow wobble
of a spinning top, is guaranteed to lead to epochs when the orbits of
Earth and comet intersect. Passing through the 'IRAS trail', annual
meteor storms of huge intensity would then be expected, with a
correspondingly enhanced risk of a Tunguska-like impact, perhaps
concentrated into brief but devastating swarms.
 |
| ©Frontiers |
| Fifth-century
celestial serpents These represent the conflict between Zeus and Typhon. The winged-serpent motif, which was widespread throughout antiquity, may have its origins in cometary activity |
In fact, a number of entities in the inner part of the Solar System,
such as the Taurid meteor stream seen in November - the bulk of meteor
dust responsible for the so-called zodiacal light and Comet Encke
itself (associated with the Taurids) - are thought to be the remnants
of a very large comet. It seems that this object was actively
disintegrating as recently as 5000 years ago, although it may be very
much older. The night sky at that time, and probably for some millennia
after, would have looked very disturbed, lit up by a bright zodiacal
light, with recurring cometary fragments drifting through the
constellations, and with a brilliant firework display recurring
annually in the form of the associated meteor storm.
Evidence for a giant comet
Is there any evidence for this giant comet in the terrestrial
record? One of the most puzzling and widespread features of early
societies is their preoccupation with the sky. People have assumed that
this was driven by the need for a calendar for both agricultural and
ritual purposes. However, this explanation does not account for the
doom-laden nature of much cosmic iconography and early sky-centred
cosmic religions associated with these societies. For example, some of
them involve celestial combat myths in which winged serpents battle it
out in the sky before one or other crashes to Earth. Numerous
prophecies of doom, from Zoroaster to the Book of Revelation, clearly
show celestial impact motifs: the Persian prophet Zoroaster (c. 500 BC)
predicts a world-end in which "Ahriman (Satan) will make a comet strike
the Earth causing a huge conflagration"; the Book of Revelation
describes a huge burning mountain falling from the sky, dropping hail
and fire on the Earth, while the Sun and Moon are darkened by smoke
pouring from the abyss; Sodom and Gomorrah were destroyed by a rain of
fire from Heaven, and so on. Cometary as well as meteor motifs are also
found in these myths (for example, Revelation has a huge, red,
multiple-headed dragon in the sky) and were recognised as such by
ancient writers.
Other hints of an interest extending beyond the practical need for a
calendar are to be found in the omen astrology of the Babylonians,
which was largely fireball-based (a fireball is an extremely bright
meteor), and in the widespread occurrence of icons apparently depicting
comets, such as the omega symbol found throughout the Near East. The
ancient swastika may be another such - for example, it explicitly
represents a cometary type in a Chinese classification scheme depicted
in a Han dynasty tomb dated 168 BC. This symbol is of great antiquity,
going back to at least 1400 BC, and is found from China through India
to the New World.
 |
| ©Frontiers |
| The
Marduk-Tiamat conflict from Babylonian mythology, dated around 1400 BC. Tiamat, representing primaeval chaos, gives birth to giant snakes, a horned serpent, assorted dragons and the like in preparation for a war with Marduk and his host. In the battle Tiamat is distended and splits in two. Marduk, victorious, constructs the heavens from her skin, creates constellations for the gods and regulates the year. The deity goes back to the third millennium BC |
Unless these speculations are backed up by 'hard evidence', however,
cosmic interpretations of history are likely to remain controversial.
Such evidence may be slowly emerging. Tree-ring studies of Irish oaks,
made by Mike Baillie of Queen's University, Belfast, reveal that there
was an abrupt climatic downturn around 2354 - 2345 BC. Digs carried out
by the archaeologists, Courty and Weiss at Tell Leilan in Northern
Syria, have revealed that, also around the same time, a catastrophic
environmental event took place. Their detailed analysis reveals
evidence not only of widespread destruction, but more specifically the
disintegration of mud-brick constructions by 'a blast from the sky'.
Around this time also, there was a near-simultaneous collapse of Bronze
Age civilisations, and evidence from many other sources of widespread
environmental disturbance in the late third millennium BC; but the
dating of the latter events is poor, and whether we can see in them a
cosmic disturbance of the Comet Encke kind is still uncertain.
The concept that an asteroid killed the dinosaurs has seeped into
popular culture over the past 15 years or so. Recently, the question:
"Could it happen to us?," has also become a matter of increasing public
interest. Within the past year, a spate of popular books and movies has
drawn attention to the issue: it seems that the perception of 'humanity
at risk from the sky' is destined to become a part of current culture.
The responsibility of the scientist concerned with the celestial
hazards is, of course, to assess them as realistically as possible. In
making this assessment, it seems that useful information may be
obtainable from a well-informed study of our early history.
Bill Napier is an astronomer at the Armagh Observatory in Northern Ireland.
E-mail: wmn@star.arm.ac.uk
SpaceWeather.com
Tue, 13 May 2008 05:15 EDT
On May 12th, a brilliant green fireball (probably meteoritic) flew over
eastern New Mexico and lit up the ground like a full Moon. Using a
Sandia Labs all-sky camera and a 60-80 MHz radio receiver, Thomas
Ashcraft not only photographed the fireball but also recorded distant
radio stations echoing eerily from the fireball's ionized tail. Click here and enjoy the show.
Gregg Easterbrook
The Atlantic
Wed, 14 May 2008 13:51 EDT
The odds that a potentially devastating space rock will hit
Earth this century may be as high as one in 10. So why isn't NASA
trying harder to prevent catastrophe?
 |
| ©Stéphane Guisard, www.astrosurf.com/sguisard |
Breakthrough ideas have a way of seeming obvious in retrospect,
and about a decade ago, a Columbia University geophysicist named Dallas
Abbott had a breakthrough idea. She had been pondering the craters left
by comets and asteroids that smashed into Earth. Geologists had counted
them and concluded that space strikes are rare events and had occurred
mainly during the era of primordial mists. But, Abbott realized, this
deduction was based on the number of craters found on land - and
because 70 percent of Earth's surface is water, wouldn't most space
objects hit the sea? So she began searching for underwater craters
caused by impacts rather than by other forces, such as volcanoes. What
she has found is spine-chilling: evidence that several enormous
asteroids or comets have slammed into our planet quite recently, in
geologic terms. If Abbott is right, then you may be here today, reading
this magazine, only because by sheer chance those objects struck the
ocean rather than land.
Abbott believes that a space object about 300 meters in diameter hit
the Gulf of Carpentaria, north of Australia, in 536 A.D. An object that
size, striking at up to 50,000 miles per hour, could release as much
energy as 1,000 nuclear bombs. Debris, dust, and gases thrown into the
atmosphere by the impact would have blocked sunlight, temporarily
cooling the planet - and indeed, contemporaneous accounts describe dim
skies, cold summers, and poor harvests in 536 and 537. "A most dread
portent took place," the Byzantine historian Procopius wrote of 536;
the sun "gave forth its light without brightness." Frost reportedly
covered China in the summertime. Still, the harm was mitigated by the
ocean impact. When a space object strikes land, it kicks up more dust
and debris, increasing the global-cooling effect; at the same time, the
combination of shock waves and extreme heating at the point of impact
generates nitric and nitrous acids, producing rain as corrosive as
battery acid. If the Gulf of Carpentaria object were to strike Miami
today, most of the city would be leveled, and the atmospheric effects
could trigger crop failures around the world.
What's more, the Gulf of Carpentaria object was a skipping stone
compared with an object that Abbott thinks whammed into the Indian
Ocean near Madagascar some 4,800 years ago, or about 2,800 B.C.
Researchers generally assume that a space object a kilometer or more
across would cause significant global harm: widespread destruction,
severe acid rain, and dust storms that would darken the world's skies
for decades. The object that hit the Indian Ocean was three to five
kilometers across, Abbott believes, and caused a tsunami in the Pacific
600 feet high - many times higher than the 2004 tsunami that struck
Southeast Asia. Ancient texts such as Genesis and the Epic of Gilgamesh
support her conjecture, describing an unspeakable planetary flood in
roughly the same time period. If the Indian Ocean object were to hit
the sea now, many of the world's coastal cities could be flattened. If
it were to hit land, much of a continent would be leveled; years of
winter and mass starvation would ensue.
At the start of her research, which has sparked much debate among
specialists, Abbott reasoned that if colossal asteroids or comets
strike the sea with about the same frequency as they strike land, then
given the number of known land craters, perhaps 100 large impact
craters might lie beneath the oceans. In less than a decade of
searching, she and a few colleagues have already found what appear to
be 14 large underwater impact sites. That they've found so many so
rapidly is hardly reassuring.
Other scientists are making equally unsettling discoveries. Only in
the past few decades have astronomers begun to search the nearby skies
for objects such as asteroids and comets (for convenience, let's call
them "space rocks"). What they are finding suggests that near-Earth
space rocks are more numerous than was once thought, and that their
orbits may not be as stable as has been assumed. There is also reason
to think that space rocks may not even need to reach Earth's surface to
cause cataclysmic damage. Our solar system appears to be a far more
dangerous place than was previously believed.
The received wisdom about the origins of the solar system goes
something like this: the sun and planets formed about 4.5 billion years
ago from a swirling nebula containing huge amounts of gas and dust, as
well as relatively small amounts of metals and other dense substances
released by ancient supernova explosions. The sun is at the center; the
denser planets, including Earth, formed in the middle region, along
with many asteroids - the small rocky bodies made of material that
failed to incorporate into a planet. Farther out are the gas-giant
planets, such as Jupiter, plus vast amounts of light elements, which
formed comets on the boundary of the solar system. Early on, asteroids
existed by the millions; the planets and their satellites were
bombarded by constant, furious strikes. The heat and shock waves
generated by these impacts regularly sterilized the young Earth. Only
after the rain of space objects ceased could life begin; by then, most
asteroids had already either hit something or found stable orbits that
do not lead toward planets or moons. Asteroids still exist, but most
were assumed to be in the asteroid belt, which lies between Mars and
Jupiter, far from our blue world.
As for comets, conventional wisdom held that they also bombarded the
planets during the early eons. Comets are mostly frozen water mixed
with dirt. An ancient deluge of comets may have helped create our
oceans; lots of comets hit the moon, too, but there the light elements
they were composed of evaporated. As with asteroids, most comets were
thought to have smashed into something long ago; and, because the solar
system is largely void, researchers deemed it statistically improbable
that those remaining would cross the paths of planets.
These standard assumptions - that remaining space rocks are few, and
that encounters with planets were mainly confined to the past - are
being upended. On March 18, 2004, for instance, a 30-meter asteroid
designated 2004 FH - a hunk potentially large enough to obliterate a
city - shot past Earth, not far above the orbit occupied by
telecommunications satellites. (Enter "2004 FH" in the search box at
Wikipedia and you can watch film of that asteroid passing through the
night sky.) Looking at the broader picture, in 1992 the astronomers
David Jewitt, of the University of Hawaii, and Jane Luu, of the
Massachusetts Institute of Technology, discovered the Kuiper Belt, a
region of asteroids and comets that starts near the orbit of Neptune
and extends for immense distances outward. At least 1,000 objects big
enough to be seen from Earth have already been located there. These
objects are 100 kilometers across or larger, much bigger than whatever
dispatched the dinosaurs; space rocks this size are referred to as
"planet killers" because their impact would likely end life on Earth.
Investigation of the Kuiper Belt has just begun, but there appear to be
substantially more asteroids in this region than in the asteroid belt,
which may need a new name.
Beyond the Kuiper Belt may lie the hypothesized Oort Cloud, thought
to contain as many as trillions of comets. If the Oort Cloud does
exist, the number of extant comets is far greater than was once
believed. Some astronomers now think that short-period comets, which
swing past the sun frequently, hail from the relatively nearby Kuiper
Belt, whereas comets whose return periods are longer originate in the
Oort Cloud.
But if large numbers of comets and asteroids are still around,
several billion years after the formation of the solar system, wouldn't
they by now be in stable orbits - ones that rarely intersect those of
the planets? Maybe not. During the past few decades, some astronomers
have theorized that the movement of the solar system within the Milky
Way varies the gravitational stresses to which the sun, and everything
that revolves around it, is exposed. The solar system may periodically
pass close to stars or groups of stars whose gravitational pull affects
the Oort Cloud, shaking comets and asteroids loose from their orbital
moorings and sending them downward, toward the inner planets.
Consider objects that are already near Earth, and the picture gets
even bleaker. Astronomers traditionally spent little time looking for
asteroids, regarding them as a lesser class of celestial bodies,
lacking the beauty of comets or the significance of planets and stars.
Plus, asteroids are hard to spot - they move rapidly, compared with the
rest of the heavens, and even the nearby ones are fainter than other
objects in space. Not until the 1980s did scientists begin
systematically searching for asteroids near Earth. They have been
finding them in disconcerting abundance.
In 1980, only 86 near-Earth asteroids and comets were known to
exist. By 1990, the figure had risen to 170; by 2000, it was 921; as of
this writing, it is 5,388. The Jet Propulsion Laboratory, part of NASA,
keeps a running tally at www.neo.jpl.nasa.gov/stats. Ten years ago, 244
near-Earth space rocks one kilometer across or more - the size that
would cause global calamity - were known to exist; now 741 are. Of the
recently discovered nearby space objects, NASA has classified 186 as
"impact risks" (details about these rocks are at
www.neo.jpl.nasa.gov/risk). And because most space-rock searches to
date have been low-budget affairs, conducted with equipment designed to
look deep into the heavens, not at nearby space, the actual number of
impact risks is undoubtedly much higher. Extrapolating from recent
discoveries, NASA estimates that there are perhaps 20,000 potentially
hazardous asteroids and comets in the general vicinity of Earth.
There's still more bad news. Earth has experienced several mass
extinctions - the dinosaurs died about 65 million years ago, and
something killed off some 96 percent of the world's marine species
about 250 million years ago. Scientists have generally assumed that
whatever caused those long-ago mass extinctions - comet impacts,
extreme volcanic activity - arose from conditions that have changed and
no longer pose much threat. It's a comforting notion - but what about
the mass extinction that occurred close to our era?
About 12,000 years ago, many large animals of North America started
disappearing - woolly mammoths, saber-toothed cats, mastodons, and
others. Some scientists have speculated that Paleo-Indians may have
hunted some of the creatures to extinction. A millennia-long mini - Ice
Age also may have been a factor. But if that's the case, what explains
the disappearance of the Clovis People, the best-documented
Paleo-Indian culture, at about the same time? Their population
stretched as far south as Mexico, so the mini - Ice Age probably was
not solely responsible for their extinction.
A team of researchers led by Richard Firestone, of the Lawrence
Berkeley National Laboratory, in California, recently announced the
discovery of evidence that one or two huge space rocks, each perhaps
several kilometers across, exploded high above Canada 12,900 years ago.
The detonation, they believe, caused widespread fires and dust clouds,
and disrupted climate patterns so severely that it triggered a
prolonged period of global cooling. Mammoths and other species might
have been killed either by the impact itself or by starvation after
their food supply was disrupted. These conclusions, though hotly
disputed by other researchers, were based on extensive examinations of
soil samples from across the continent; in strata from that era,
scientists found widely distributed soot and also magnetic grains of
iridium, an element that is rare on Earth but common in space. Iridium
is the meteor-hunter's lodestar: the discovery of iridium dating back
65 million years is what started the geologist Walter Alvarez on his
path-breaking theory about the dinosaurs' demise.
A more recent event gives further cause for concern. As buffs of the
television show The X Files will recall, just a century ago, in 1908, a
huge explosion occurred above Tunguska, Siberia. The cause was not a
malfunctioning alien star-cruiser but a small asteroid or comet that
detonated as it approached the ground. The blast had hundreds of times
the force of the Hiroshima bomb and devastated an area of several
hundred square miles. Had the explosion occurred above London or Paris,
the city would no longer exist. Mark Boslough, a researcher at the
Sandia National Laboratory, in New Mexico, recently concluded that the
Tunguska object was surprisingly small, perhaps only 30 meters across.
Right now, astronomers are nervously tracking 99942 Apophis, an
asteroid with a slight chance of striking Earth in April 2036. Apophis
is also small by asteroid standards, perhaps 300 meters across, but it
could hit with about 60,000 times the force of the Hiroshima bomb -
enough to destroy an area the size of France. In other words, small
asteroids may be more dangerous than we used to think - and may do
considerable damage even if they don't reach Earth's surface.
 |
| ©NASA/NSSDC |
| ASTEROID 243 IDA, about 35 miles long, and its moon |
Until recently, nearly all the thinking about the risks of
space-rock strikes has focused on counting craters. But what if most
impacts don't leave craters? This is the prospect that troubles
Boslough. Exploding in the air, the Tunguska rock did plenty of damage,
but if people had not seen the flashes, heard the detonation, and
traveled to the remote area to photograph the scorched, flattened
wasteland, we'd never know the Tunguska event had happened. Perhaps a
comet or two exploding above Canada 12,900 years ago spelled the end
for saber-toothed cats and Clovis society. But no obvious crater
resulted; clues to the calamity were subtle and hard to come by.
Comets, asteroids, and the little meteors that form pleasant
shooting stars approach Earth at great speeds - at least 25,000 miles
per hour. As they enter the atmosphere they heat up, from friction, and
compress, because they decelerate rapidly. Many space rocks explode
under this stress, especially small ones; large objects are more likely
to reach Earth's surface. The angle at which objects enter the
atmosphere also matters: an asteroid or comet approaching straight down
has a better chance of hitting the surface than one entering the
atmosphere at a shallow angle, as the latter would have to plow through
more air, heating up and compressing as it descended. The object or
objects that may have detonated above Canada 12,900 years ago would
probably have approached at a shallow angle.
If, as Boslough thinks, most asteroids and comets explode before
reaching the ground, then this is another reason to fear that the
conventional thinking seriously underestimates the frequency of
space-rock strikes - the small number of craters may be lulling us into
complacency. After all, if a space rock were hurtling toward a city,
whether it would leave a crater would not be the issue - the explosion
would be the issue.
A generation ago, the standard assumption was that a dangerous
object would strike Earth perhaps once in a million years. By the
mid-1990s, researchers began to say that the threat was greater:
perhaps a strike every 300,000 years. This winter, I asked William
Ailor, an asteroid specialist at The Aerospace Corporation, a think
tank for the Air Force, what he thought the risk was. Ailor's answer: a
one-in-10 chance per century of a dangerous space-object strike.
Regardless of which estimate is correct, the likelihood of an event
is, of course, no predictor. Even if space strikes are likely only once
every million years, that doesn't mean a million years will pass before
the next impact - the sky could suddenly darken tomorrow. Equally
important, improbable but cataclysmic dangers ought to command
attention because of their scope. A tornado is far more likely than an
asteroid strike, but humanity is sure to survive the former. The
chances that any one person will die in an airline crash are minute,
but this does not prevent us from caring about aviation safety. And as
Nathan Myhrvold, the former chief technology officer of Microsoft, put
it, "The odds of a space-object strike during your lifetime may be no
more than the odds you will die in a plane crash - but with space
rocks, it's like the entire human race is riding on the plane."
Given the scientific findings, shouldn't space rocks be one of
NASA's priorities? You'd think so, but Dallas Abbott says NASA has
shown no interest in her group's work: "The NASA people don't want to
believe me. They won't even listen."
NASA supports some astronomy to search for near-Earth objects, but
the agency's efforts have been piecemeal and underfunded, backed by
less than a tenth of a percent of the NASA budget. And though altering
the course of space objects approaching Earth appears technically
feasible, NASA possesses no hardware specifically for this purpose, has
nearly nothing in development, and has resisted calls to begin work on
protection against space strikes. Instead, NASA is enthusiastically
preparing to spend hundreds of billions of taxpayers' dollars on a
manned moon base that has little apparent justification. "What is in
the best interest of the country is never even mentioned in current
NASA planning," says Russell Schweickart, one of the Apollo astronauts
who went into space in 1969, who is leading a campaign to raise
awareness of the threat posed by space rocks. "Are we going to let a
space strike kill millions of people before we get serious about this?"
he asks.
In January, I attended an internal NASA conference, held at agency
headquarters, during which NASA's core goals were presented in a
PowerPoint slideshow. Nothing was said about protecting Earth from
space strikes - not even researching what sorts of spacecraft might be
used in an approaching-rock emergency. Goals that were listed included
"sustained human presence on the moon for national preeminence" and
"extend the human presence across the solar system and beyond."
Achieving national preeminence - isn't the United States pretty
well-known already? As for extending our presence, a manned mission to
Mars is at least decades away, and human travel to the outer planets is
not seriously discussed by even the most zealous advocates of space
exploration. Sending people "beyond" the solar system is inconceivable
with any technology that can reasonably be foreseen; an interstellar
spaceship traveling at the fastest speed ever achieved in space flight
would take 60,000 years to reach the next-closest star system.
After the presentation, NASA's administrator, Michael Griffin, came
into the room. I asked him why there had been no discussion of space
rocks. He said, "We don't make up our goals. Congress has not
instructed us to provide Earth defense. I administer the policy set by
Congress and the White House, and that policy calls for a focus on
return to the moon. Congress and the White House do not ask me what I
think." I asked what NASA's priorities would be if he did set the
goals. "The same. Our priorities are correct now," he answered. "We are
on the right path. We need to go back to the moon. We don't need a
near-Earth-objects program." In a public address about a month later,
Griffin said that the moon-base plan was "the finest policy framework
for United States civil space activities that I have seen in 40 years."
Actually, Congress has asked NASA to pay more attention to space
rocks. In 2005, Congress instructed the agency to mount a sophisticated
search of the proximate heavens for asteroids and comets, specifically
requesting that NASA locate all near-Earth objects 140 meters or larger
that are less than 1.3 astronomical units from the sun - roughly out to
the orbit of Mars. Last year, NASA gave Congress its reply: an advanced
search of the sort Congress was requesting would cost about $1 billion,
and the agency had no intention of diverting funds from existing
projects, especially the moon-base initiative.
How did the moon-base idea arise? In 2003, after the shuttle
Columbia was lost, manned space operations were temporarily shut down,
and the White House spent a year studying possible new missions for
NASA. George W. Bush wanted to announce a voyage to Mars. Every Oval
Office occupant since John F. Kennedy knows how warmly history has
praised him for the success of his pledge to put men on the moon; it's
only natural that subsequent presidents would dream about securing
their own place in history by sending people to the Red Planet. But the
technical barriers and even the most optimistic cost projections for a
manned mission to Mars are prohibitive. So in 2004, Bush unveiled a
compromise plan: a permanent moon base that would be promoted as a
stepping-stone for a Mars mission at some unspecified future date. As
anyone with an aerospace engineering background well knows, stopping at
the moon, as Bush was suggesting, actually would be an impediment to
Mars travel, because huge amounts of fuel would be wasted landing on
the moon and then blasting off again. Perhaps something useful to a
Mars expedition would be learned in the course of building a moon base;
but if the goal is the Red Planet, then spending vast sums on lunar
living would only divert that money from the research and development
needed for Mars hardware. However, saying that a moon base would one
day support a Mars mission allowed Bush to create the impression that
his plan would not merely be restaging an effort that had already been
completed more than 30 years before. For NASA, a decades-long project
to build a moon base would ensure a continuing flow of money to its
favorite contractors and to the congressional districts where
manned-space-program centers are located. So NASA signed on to the
proposal, which Congress approved the following year.
It is instructive, in this context, to consider the agency's
rhetoric about China. The Chinese manned space program has been
improving and is now about where the U.S. program was in the mid-1960s.
Stung by criticism that the moon-base project has no real justification
- 37 years ago, President Richard Nixon cancelled the final planned
Apollo moon missions because the program was accomplishing little at
great expense; as early as 1964, the communitarian theorist Amitai
Etzioni was calling lunar obsession a "moondoggle" - NASA is selling
the new plan as a second moon race, this time against Beijing. "I'll be
surprised if the Chinese don't reach the moon before we return,"
Griffin said. "China is now a strategic peer competitor to the United
States in space. China is drawing national prestige from achievements
in space, and there will be a tremendous shift in national prestige
toward Beijing if the Chinese are operating on the moon and we are not.
Great nations have always operated on the frontiers of their era. The
moon is the frontier of our era, and we must outperform the Chinese
there."
Wouldn't shifting NASA's focus away from wasting money on the moon
and toward something of clear benefit for the entire world -
identifying and deflecting dangerous space objects - be a surer route
to enhancing national prestige? But NASA's institutional instinct is
not to ask, "What can we do in space that makes sense?" Rather, it is
to ask, "What can we do in space that requires lots of astronauts?"
That finding and stopping space rocks would be an expensive mission
with little role for the astronaut corps is, in all likelihood, the
principal reason NASA doesn't want to talk about the asteroid threat.
NASA's lack of interest in defending against space objects leaves a
void the Air Force seems eager to fill. The Air Force has the world's
second-largest space program, with a budget of about $11 billion - $6
billion less than NASA's. The tension between the two entities is
long-standing. Many in the Air Force believe the service could achieve
U.S. space objectives faster and more effectively than NASA. And the
Air Force simply wants flyboys in orbit: several times in the past, it
has asked Congress to fund its own space station, its own space plane,
and its own space-shuttle program. Now, with NASA all but ignoring the
space-object threat, the Air Force appears to be seizing an opportunity.
All known space rocks have been discovered using telescopes designed
for traditional "soda straw" astronomy - that is, focusing on a small
patch of sky. Now the Air Force is funding the first research
installation designed to conduct panoramic scans of the sky, a
telescope complex called Pan-STARRS, being built by the University of
Hawaii. By continuously panning the entire sky, Pan-STARRS should be
able to spot many near-Earth objects that so far have gone undetected.
The telescope also will have substantially better resolving power and
sensitivity than existing survey instruments, enabling it to find small
space rocks that have gone undetected because of their faintness.
The Pan-STARRS project has no military utility, so why is the Air
Force the sponsor? One speculation is that Pan-STARRS is the Air
Force's foot in the door for the Earth-defense mission. If the Air
Force won funding to build high-tech devices to fire at asteroids, this
would be a major milestone in its goal of an expanded space presence.
But space rocks are a natural hazard, not a military threat, and an Air
Force Earth-protection initiative, however gallant, would probably
cause intense international opposition. Imagine how other governments
would react if the Pentagon announced, "Don't worry about those
explosions in space - we're protecting you."
Thus, the task of defending Earth from objects falling from the
skies seems most fitting for NASA, or perhaps for a multinational
civilian agency that might be created. Which raises the question: What
could NASA, or anyone else, actually do to provide a defense?
Russell Schweickart, the former Apollo astronaut, runs the B612
Foundation (B612 is the asteroid home of Saint-Exupéry's Little
Prince). The foundation's goal is to get NASA officials, Congress, and
ultimately the international community to take the space-rock threat
seriously; it advocates testing a means of precise asteroid tracking,
then trying to change the course of a near-Earth object.
Current telescopes cannot track asteroids or comets accurately
enough for researchers to be sure of their courses. When 99942 Apophis
was spotted, for example, some calculations suggested it would strike
Earth in April 2029, but further study indicates it won't - instead,
Apophis should pass between Earth and the moon, during which time it
may be visible to the naked eye. The Pan-STARRS telescope complex will
greatly improve astronomers' ability to find and track space rocks, and
it may be joined by the Large Synoptic Survey Telescope, which would
similarly scan the entire sky. Earlier this year, the software
billionaires Bill Gates and Charles Simonyi pledged $30 million for
work on the LSST, which proponents hope to erect in the mountains of
Chile. If it is built, it will be the first major telescope to
broadcast its data live over the Web, allowing countless professional
and amateur astronomers to look for undiscovered asteroids.
Schweickart thinks, however, that even these instruments will not be
able to plot the courses of space rocks with absolute precision. NASA
has said that an infrared telescope launched into an orbit near Venus
could provide detailed information on the exact courses of space rocks.
Such a telescope would look outward from the inner solar system toward
Earth, detect the slight warmth of asteroids and comets against the
cold background of the cosmos, and track their movements with
precision. Congress would need to fund a near-Venus telescope, though,
and NASA would need to build it - neither of which is happening.
Another means of gathering data about a potentially threatening
near-Earth object would be to launch a space probe toward it and attach
a transponder, similar to the transponders used by civilian airliners
to report their exact locations and speed; this could give researchers
extremely precise information on the object's course. There is no doubt
that a probe can rendezvous with a space rock: in 2005, NASA smashed a
probe called Deep Impact into the nucleus of comet 9P/Tempel in order
to vaporize some of the material on the comet's surface and make a
detailed analysis of it. Schweickart estimates that a mission to attach
a transponder to an impact-risk asteroid could be staged for about $400
million - far less than the $11.7 billion cost to NASA of the 2003
Columbia disaster.
Then what? In the movies, nuclear bombs are used to destroy space
rocks. In NASA's 2007 report to Congress, the agency suggested a
similar approach. But nukes are a brute-force solution, and because an
international treaty bans nuclear warheads in space, any proposal to
use them against an asteroid would require complex diplomatic
agreements. Fortunately, it's likely that just causing a slight change
in course would avert a strike. The reason is the mechanics of orbits.
Many people think of a planet as a vacuum cleaner whose gravity sucks
in everything in its vicinity. It's true that a free-falling body will
plummet toward the nearest source of gravity - but in space,
free-falling bodies are rare. Earth does not plummet into the sun,
because the angular momentum of Earth's orbit is in equilibrium with
the sun's gravity. And asteroids and comets swirl around the sun with
tremendous angular momentum, which prevents them from falling toward
most of the bodies they pass, including Earth.
For any space object approaching a planet, there exists a "keyhole"
- a patch in space where the planet's gravity and the object's momentum
align, causing the asteroid or comet to hurtle toward the planet.
Researchers have calculated the keyholes for a few space objects and
found that they are tiny, only a few hundred meters across - pinpoints
in the immensity of the solar system. You might think of a keyhole as
the win-a-free-game opening on the 18th tee of a cheesy, incredibly
elaborate miniature-golf course. All around the opening are rotating
windmills, giants stomping their feet, dragons walking past, and other
obstacles. If your golf ball hits the opening precisely, it will roll
down a pipe for a hole in one. Miss by even a bit, and the ball caroms
away.
Tiny alterations might be enough to deflect a space rock headed
toward a keyhole. "The reason I am optimistic about stopping
near-Earth-object impacts is that it looks like we won't need to use
fantastic levels of force," Schweickart says. He envisions a
"gravitational tractor," a spacecraft weighing only a few tons - enough
to have a slight gravitational field. If an asteroid's movements were
precisely understood, placing a gravitational tractor in exactly the
right place should, ever so slowly, alter the rock's course, because
low levels of gravity from the tractor would tug at the asteroid. The
rock's course would change only by a minuscule amount, but it would
miss the hole-in-one pipe to Earth.
Will the gravitational-tractor idea work? The B612 Foundation
recommends testing the technology on an asteroid that has no chance of
approaching Earth. If the gravitational tractor should prove
impractical or ineffective, other solutions could be considered.
Attaching a rocket motor to the side of an asteroid might change its
course. So might firing a laser: as materials boiled off the asteroid,
the expanding gases would serve as a natural jet engine, pushing it in
the opposite direction.
But when it comes to killer comets, you'll just have to lose sleep
over the possibility of their approach; there are no proposals for what
to do about them. Comets are easy to see when they are near the sun and
glowing but are difficult to detect at other times. Many have
"eccentric" orbits, spending centuries at tremendous distances from the
sun, then falling toward the inner solar system, then slingshotting
away again. If you were to add comets to one of those classroom models
of the solar system, many would need to come from other floors of the
building, or from another school district, in order to be to scale.
Advanced telescopes will probably do a good job of detecting most
asteroids that pass near Earth, but an unknown comet suddenly headed
our way would be a nasty surprise. And because many comets change
course when the sun heats their sides and causes their frozen gases to
expand, deflecting or destroying them poses technical problems to which
there are no ready solutions. The logical first step, then, seems to be
to determine how to prevent an asteroid from striking Earth and hope
that some future advance, perhaps one building on the asteroid work,
proves useful against comets.
None of this will be easy, of course. Unlike in the movies, where
impossibly good-looking, wisecracking men and women grab space suits
and race to the launchpad immediately after receiving a warning that
something is approaching from space, in real life preparations to
defend against a space object would take many years. First the
necessary hardware must be built - quite possibly a range of space
probes and rockets. An asteroid that appeared to pose a serious risk
would require extensive study, and a transponder mission could take
years to reach it. International debate and consensus would be needed:
the possibility of one nation acting alone against a space threat or
of, say, competing U.S. and Chinese missions to the same object, is
more than a little worrisome. And suppose Asteroid X appeared to
threaten Earth. A mission by, say, the United States to deflect or
destroy it might fail, or even backfire, by nudging the rock toward a
gravitational keyhole rather than away from it. Asteroid X then hits
Costa Rica; is the U.S. to blame? In all likelihood, researchers will
be unable to estimate where on Earth a space rock will hit.
Effectively, then, everyone would be threatened, another reason nations
would need to act cooperatively - and achieving international
cooperation could be a greater impediment than designing the technology.
We will soon have a new president, and thus an opportunity to
reassess NASA's priorities. Whoever takes office will decide whether
the nation commits to spending hundreds of billions of dollars on a
motel on the moon, or invests in space projects of tangible benefit -
space science, environmental studies of Earth, and readying the world
for protection against a space-object strike. Although the moon-base
initiative has been NASA's focus for four years, almost nothing has yet
been built for the project, and comparatively little money has been
spent; current plans don't call for substantial funding until the
space-shuttle program ends, in 2010. This suggests that NASA could back
off from the moon base without having wasted many resources. Further,
the new Ares rocket NASA is designing for moon missions might be just
the ticket for an asteroid-deflection initiative.
Congress, too, ought to look more sensibly at space priorities.
Because it controls federal funding, Congress holds the trump cards. In
2005, it passively approved the moon-base idea, seemingly just as
budgetary log-rolling to maintain spending in the congressional
districts favored under NASA's current budget hierarchy. The House and
Senate ought to demand that the space program have as its first
priority returning benefits to taxpayers. It's hard to imagine how
taxpayers could benefit from a moon base. It's easy to imagine them
benefiting from an effort to protect our world from the ultimate
calamity.
Valerie Castro
KOB-TV
Mon, 12 May 2008 05:16 EDT
It turns out a mysterious flash of lights over the Sandia Crest was most likely a meteor.
The bright streak was spotted just after 2:00 Monday morning.
Video of the flashing light was captured by an observatory near Santa Fe.
According to a UNM scientist, it was most likely a meteor passing through the earth's atmosphere.
It's a rare sight for anyone to witness, but the real treasure is finding the meteorite once it lands.
"It would be worth something scientifically for sure, and you know
everybody is interested in finding meteorites that come from this
fireball event," said UNM research scientist Dr. James Karner.
Dr. Karner says the dry deserts of New Mexico make it easier to spot meteorites on the ground.
Thomas Ashcraft, the man who captured the video from his
observatory, says the space rock probably landed in eastern New Mexico
or the Texas panhandle.
Oahu North Shore Hawaii Mystery Jolt
KGMB9 News
Tue, 13 May 2008 01:29 EDT
KGMB9 has made multiple calls, but so far what caused a jolt on Oahu's North Shore Tuesday night, is a mystery.
Several families in Pupukea say they felt a jolt just before 10 that night.
Kate from Waimea Bay wrote, "We felt our home shake 3 consecutive times. It felt like a small earthquake."
Kim from Mokuleia wrote "it was felt very strongly here, and we
suspect the military had something to do with it. it was just one large
jolt and did not feel like an earthquake."
Lindsey from Laie felt it too, and wrote "I felt something here in
Laie. Makes me wonder if seeing 4-5 busloads of military going toward
Kahuku had anything to do with it."
Other callers reported everything from hearing giant booms on the
North Shore, to wondering if it was a sonic boom. One even told us he
thought it was an unusually loud fireworks show at Aloha Tower.
KGMB9 has checked with the Pacific Tsunami Warning Center and the
United States Geological Survey, but found no record of an earthquake.
KGMB9 also called the Honolulu Fire Dept., Honolulu Police, Oahu Civil
Defense, Hawaiian Electric Company, and the Board of Water Supply. So
far none of those agencies know what it may have been.
KGMB9 did speak to the Army and Air Force. Both say they had no
training exercises that night. KGMB9 is still waiting for calls back
from the Marines, Navy, and Air National Guard.
Aaron Gronstal
Astrobiology Magazine
Thu, 15 May 2008 15:27 EDT
Asteroid and comet impacts on Earth can cause catastrophic extinction events. They can also bring life back, new research shows.
Many scientists believe that a massive rock from space came crashing
down 65 million years ago at the end of the Cretaceous Period. The
resulting blast set forests ablaze. The skies of Earth were filled with
ash that blocked out the sun and the planet went cold. Vegetation died
in the absence of sunlight. Shortly thereafter, the dinosaurs and many
other life forms on Earth went extinct. Millions of years of evolution
were wiped clean in an instant.
It's frightening that one instantaneous event could completely
change the face of life on Earth. However, a new study supports
longstanding suggestions that asteroid impacts could also help spread
life throughout the universe.
Rocks that are ejected from the Earth - or any other life-bearing
planet - by an asteroid impact might actually protect microbes living
inside them while they float through space. These rocks could then fall
to the surface of other planets, or even back to their planet of
origin. In this way, the microbes could return to their home planet and
're-colonize' the surface after the disastrous effects of the asteroid
impact have worn off.
Blast Off
In order for organisms to survive a trip into orbit, they must
endure a series of life-threatening events. First there's the asteroid
impact itself. Then there's the force of being launched into space.
Next, they must travel in the harsh environment of space until a
planet's gravity reels them in. This means facing an environment of
extreme cold, intense radiation and vacuum exposure. Finally, they need
to fall down through the atmosphere, experiencing extreme pressure,
heating and the shock of landing.
Previous studies have shown that some rock-inhabiting organisms,
known as 'endoliths', might be able to survive a trip through space and
a plunge through a planet's atmosphere to the surface. However, nobody
knew whether these organisms could survive the initial trip into space.
Recently, an international team of researchers, led by Gerda Horneck
of the Institute of Aerospace Medicine in Köln, Germany, selected a
number of hardy microbes from Earth and tested their ability to
'hitchhike' aboard rocks similar to martian meteorites. The organisms
used in the study included bacterial endospores, endolithic
cyanobaterica and lichens. This selection provided a wider range of
organisms than in other studies performed to date, including not just
simple bacteria but also more complex eukaryotic organisms.
The researchers looked at previous studies of martian meteorites
that provided information about the kinds of forces needed to eject
rocks from a large planet. Using this data, the researchers developed a
series of tests designed to simulate these pressures on the selected
organisms. By smashing the life-containing rocks between metal plates,
the researchers were able to determine which organisms are capable of
surviving different pressures caused by asteroid impacts and ejection
into space. Ultimately, they discovered that a wide range of organisms
would be capable of surviving impacts on Mars or Earth.
"Our results enlarge the number of potential organisms that might be
able to reseed a planetary surface after early very large impact
events, and suggest that such a re-seeding scenario on a planetary
surface is possible with diverse organisms," the researchers report.
More details of the study can be found in the Spring 2008 (Volume 8, Number 1) issue of the journal Astrobiology.
Dr. Tony Phillips
NASA
Wed, 21 May 2008 05:23 EDT
Not so long ago, anyone claiming to see
flashes of light on the Moon would be viewed with deep suspicion by
professional astronomers. Such reports were filed under "L" ... for
lunatic.
Not anymore. Over the past two and a half years, NASA astronomers have observed the Moon flashing at them not just once but one hundred times.
"They're explosions caused by meteoroids hitting the Moon," explains
Bill Cooke, head of NASA's Meteoroid Environment Office at the Marshall
Space Flight Center (MSFC). "A typical blast is about as powerful as a
few hundred pounds of TNT and can be photographed easily using a
backyard telescope."
As an example, he offers this video of an impact near crater Gauss on January 4, 2008:
 |
| ©NASA |
| A
lunar impact on Jan. 4, 2008. This is number 86 on the list of 100 impacts recorded by the MEO team since their survey began in 2005.Larger movies: 0.8 MB gif, 5.9 MB avi. |
The impactor was a tiny fragment of extinct comet 2003 EH1. Every
year in early January, the Earth-Moon system passes through a stream of
debris from that comet, producing the well-known Quadrantid meteor
shower. Here on Earth, Quadrantids disintegrate as flashes of light in
the atmosphere; on the airless Moon they hit the ground and explode.
"We started our monitoring program in late 2005 after NASA announced
plans to return astronauts to the Moon," says team leader Rob Suggs of
the MSFC. If people were going to be walking around up there, "it
seemed like a good idea to measure how often the Moon was getting hit."
"Almost immediately, we detected a flash."
That first detection - "I'll never forget it," he says--came on Nov.
7, 2005, when a piece of Comet Encke about the size of a baseball hit
Mare Imbrium. The resulting explosion produced a 7th magnitude flash,
too dim for the naked eye but an easy target for the team's 10-inch
telescope.
A common question, says Cooke, is "how can something explode on the Moon? There's no oxygen up there."
These explosions don't require oxygen or combustion. Meteoroids hit
the moon with tremendous kinetic energy, traveling 30,000 mph or
faster. "At that speed, even a pebble can blast a crater several feet
wide. The impact heats up rocks and soil on the lunar surface hot
enough to glow like molten lava--hence the flash."
During meteor showers such as the Quadrantids or Perseids, when the
Moon passes through dense streams of cometary debris, the rate of lunar
flashes can go as high as one per hour. Impacts subside when the Moon
exits the stream, but curiously the rate never goes to zero.
"Even when no meteor shower is active, we still see flashes," says Cooke.
 |
| ©NASA |
| Above: A map of the 100 explosions observed since late 2005. A complete list with lunar coordinates is available here. |
These "off-shower" impacts come from a vast swarm of natural space
junk littering the inner solar system. Bits of stray comet dust and
chips off old asteroids pepper the Moon in small but ultimately
significant numbers. Earth gets hit, too, which is why on any given
night you can stand under a dark sky and see a few meteors per hour
glide overhead - no meteor shower required. Over the course of a year,
these random or "sporadic" impacts outnumber impacts from organized
meteor showers by a ratio of approximately 2:1.
"That's an important finding," says Suggs. "It means there's no time of year when the Moon is impact-free."
Fortunately, says Cooke, astronauts are in little danger. "The odds
of a direct hit are negligible. If, however, we start building big
lunar outposts with lots of surface area, we'll have to carefully
consider these statistics and bear in mind the odds of a structure
getting hit."
Secondary impacts are the greater concern. When meteoroids strike
the Moon, debris goes flying in all directions. A single meteoroid
produces a spray consisting of thousands of "secondary" particles all
traveling at bullet-like velocities. This could be a problem because,
while the odds of a direct hit are low, the odds of a secondary hit may
be significantly greater. "Secondary particles smaller than a
millimeter could pierce a spacesuit," notes Cooke.
At present, no one knows how far and wide secondary particles
travel. To get a handle on the problem, Cooke, Suggs and colleagues are
shooting artificial meteoroids at simulated moon dust and measuring the
spray. This work is being done at the Vertical Gun Range at NASA's Ames
Research Center in Mountain View, CA: full story.
 |
| ©NASA |
| A
simulated meteoroid explodes on impact at the NASA/Ames Vertical Gun Range. This is a genuine photo showing the spray of secondary particles: more. See story here. |
Meanwhile, back at the observatory, the team has upgraded their
original 10-inch (25 cm) telescope to a pair of telescopes, one 14-inch
(36 cm) and one 20-inch (51 cm), located at the Marshall Space Flight
Center in Alabama. They've also established a new observing site in
Georgia with a 14-inch telescope. Multiple telescopes allow double- and
triple-checking of faint flashes and improve the statistical
underpinnings of the survey.
"The Moon is still flashing," says Suggs. Indeed, during the writing of this story, three more impacts were detected.
New title: 103 Explosions on the Moon.
Stay tuned to Science@NASA for a follow-up story describing how amateur astronomers can participate in this research.
Comment: Left
unsaid here is that the earth, being approximately 3.7 times the
diameter of the moon has an equally exposed area of about 14 times that
of the moon. Therefore the earth got hit with about 1400 meteors in the
same time period. But they're only seeing half the area of the moon.
Thus the true number is double that.
UK: Readers react to red objects in the sky
Sam Greenway
Bromsgrove Advertiser
Fri, 23 May 2008 14:22 EDT
Skygazers have been gripped by our mysterious
red objects story - last week's front page - with many saying they
witnessed them hovering in Bromsgrove skies.
We have had an amazingly large response from readers to the article.
Within hours of the newspaper hitting the streets our newsroom was
inundated with calls and e-mails from residents letting us know what
they saw.
Last week's story concerned Pat Maguire's sighting of two extremely
bright red, unidentified objects heading towards Droitwich on May 16.
However, some of you are now telling us they were out on Saturday
evening, into Sunday morning, and others have seen them in Bromsgrove
skies over the last year.
One Bromsgrove resident said he saw "frequent flashes from the Wychbold area as bright as sheet lightning."
New Road resident Margaret Harries and Wendy Wright, from Harwood
Park, also saw flashes, but Sidemoor resident Patrick Gunnell said the lights changed colour to orange, then yellow.
Town resident Shaun Middlemas said the object appeared to move like a "weather rocket" and launch a probe on a parachute.
Delivery driver Sameer Mitter came to a standstill, distracted by a
strange object - the shape of which he has sent to us (as above).
One explanation is they were Chinese lanterns which, when lit, rise
into the sky using hot air from its own flame to power it. However,
descriptions do vary from this.
Some have described the objects as balls of flame, while
others say they looked like burning hot air balloons, helicopters, even
planes.
Many say the objects dropped out of the sky, turning black, then
seemingly disappeared. Despite differences surrounding their
appearance, and number, the overwhelming majority say they were silent.
Local UFO researcher, John Hanson, who has a written a series of
volumes dating from 1940 to 2008 cataloguing the day-by-day account of
UFO activity in the UK, said: "Chinese lanterns can usually explain
some of the phenomena, but it would be wrong to say it accounts for all.
"Strange things are happening out there," said Alvechurch-based Mr Hanson.
Mark Blackmore, from Breme Park, simply said: "Whatever it was, it was a nice sight for a while."
Meanwhile, John Hanson is now appealing to any residents who saw the objects to contact him on 0121 445 0340.
Researchers will study ways to deflect asteroids
Iowa State University
Mon, 26 May 2008 14:37 EDT
An Asteroid Deflection Research Center (ADRC) has been established
on the Iowa State campus to bring researchers from around the world to
develop asteroid deflection technologies. The center was signed into
effect in April by the Office of the Executive Vice President and
Provost.
"In the early 1990s, scientists around the world initiated studies
to assess and devise methods to prevent near-Earth objects from
striking Earth," said Bong Wie, the Vance D. Coffman Chair Professor in
Aerospace Engineering and director of the center. "However, it is now
2008, and there is no consensus on how to reliably deflect them in a
timely manner," he noted.
Wie, whose research expertise includes space vehicle dynamics and
control, modeling and control of large space structures, and solar sail
flight control system development and mission design, joined the Iowa
State faculty last August. "I am very happy that Professor Bong Wie has
joined the faculty at ISU," said Elizabeth Hoffman, executive vice
president and provost. "His work on asteroid deflection is exciting and
of great importance."
The ADRC will host an International Symposium on Asteroid Deflection
Technology in fall 2008. Scientists and engineers from NASA, the
European Space Agency, academia, and the aerospace industry will be
invited to the Iowa State campus to formulate a roadmap for developing
asteroid deflection technologies.
Despite the lack of an immediate threat from an asteroid strike,
scientific evidence suggests the importance of researching preventive
measures. Sixty-five million years ago, a six-mile-wide asteroid struck
near the Yucatan Peninsula in Mexico and created the 106-mile-diameter
Chicxulub Crater. Most scientists now believe that a global climate
change caused by this asteroid impact may have led to the dinosaur
extinction. Seventy-four million years ago, a smaller one-mile-wide
asteroid struck in central Iowa, creating the Manson Crater. Now
covered with soil, it is the largest crater in North America at more
than 23 miles across.
Just 100 years ago, June 30, 1908, an asteroid or comet estimated at
100 - 200 feet in diameter exploded in the skies above Tunguska,
Siberia. Known as the Tunguska Event, the explosion flattened trees and
killed other vegetation over a 500,000-acre area. But if the explosion
had occurred four hours later, it would have destroyed St. Petersburg
or Moscow with an equivalent energy level of about 500 Hiroshima
nuclear bombs.
The potential for such devastation has astronomers scanning the
skies to find and track asteroids that pose a danger, and it has Wie
initiating this concerted research effort now before any asteroids are
discovered heading toward Earth.
Last November, NASA reported 900 known potentially hazardous objects
(PHOs), most of which are asteroids. PHOs are defined as objects larger
than 492 feet in diameter whose trajectories bring them to within about
4.6 million miles of the Earth's orbit. NASA scientists estimate the
total population of PHOs to be around 20,000. "However," Wie said, "the
asteroid we have to worry about is the asteroid that we don't know."
"Developing technologies that can be used to prevent or mitigate
threats from asteroids while also advancing space exploration is a
challenge we accept as we work to assure a high quality of life for
future generations," said Mark J. Kushner, dean of Iowa State's College
of Engineering. "This research center serves as an excellent
opportunity to provide leadership on an issue that has worldwide
implications."
According to Tom Shih, professor and chair of aerospace engineering, "the
potential for a major catastrophe created by an asteroid impacting
Earth is very real. It is a matter of when, and humankind must be
prepared for it. Our aerospace engineering department
strongly supports Professor Bong Wie's effort in establishing this
center to address the engineering and science issues of asteroid
deflection."
Both high-energy nuclear explosions and low-energy non-nuclear
alternatives will be studied as deflection techniques. The nuclear
approach, which is often assessed to be 10 - 100 times more effective
than non-nuclear approaches as stated in NASA's 2007 report to
Congress, will be researched to verify its effectiveness and determine
its practical viability, according to Wie.
"A 20-meter (66 feet) standoff distance is often mentioned in the
literature for a maximum velocity change of a 1-kilometer (0.6 mile)
asteroid. However, we have to determine how close the nuclear explosion
must be to effectively change the orbital trajectories of asteroids of
different types, sizes, and shapes," Wie explained. "We will develop
high-fidelity physical models to reliably predict the velocity change
and fragmentation caused by a nuclear standoff explosion."
The non-nuclear alternatives include kinetic impactors and slow-pull
gravity tractors. Wie, who has previously worked on solar sail
technology as applied to asteroid deflection, will present his recent
study, "Multiple gravity tractors in halo orbits for towing a target
asteroid," at the American Institute of Aeronautics and Astronautics
Astrodynamics Specialists Conference in August. His paper has been
accepted for publication in the AIAA Journal of Guidance, Control, and Dynamics.
The chances of having to use deflection technologies on an asteroid
in the near future are admittedly remote. Scientists estimate the
frequency of an extinction-class (6 miles in diameter or larger) object
striking Earth as once every 50 - 100 million years, and for a 200-foot
or larger object as once every 100 - 500 years.
The technologies that will be developed, including precision orbital
guidance and navigation and control, however, have other applications
as well. These may include future advanced space vehicles that will
carry astronauts to an asteroid or Mars and homeland security
applications.
Pilot saw flaming object near jet after takeoff in Houston
USA Today
Tue, 27 May 2008 15:33 EDT
Houston - A Continental Airlines pilot told air traffic controllers that an object with a flaming tail and a trail of smoke flew in front of the plane shortly after takeoff, FBI officials said.
The FBI's Joint Terrorism Task Force is involved in the
investigation, but officials said they believe the object seen by the
pilot just east of Houston's airport on Monday was a model rocket.
Officials are unsure how high the object flew or how close it came
to the plane, Federal Aviation Administration spokesman Roland Herwig
said.
The Boeing 737 carried 148 passengers, authorities said. The plane
was never in danger and landed safely, said Scott Wilson, a spokesman
for the FBI's Cleveland office.
The FBI routinely looks into any suspicious activity that involves an airplane, bureau spokeswoman Shauna Dunlap said.
"We don't know if it was a rocket or what," she said. "We will interview everyone and determine the validity of what was seen."
Continental Airlines spokeswoman Kelly Cripe would not discuss what crewmembers saw.
Model rockets can reach as high as 40,000 feet, although enthusiasts
are supposed to notify the FAA if a rocket is entering controlled
airspace, said Robert Morehead of the Amateur Spaceflight Association
in Houston.
The Associated Press
Tue, 27 May 2008 21:22 EDT
AMERICAN FORK -- Three American Fork High School are earning accolades for their stargazing.
Bryce Tholl, Clinton McClesky and Karlee Craig identified a combined
four asteroids as part of a NASA program tied to their astronomy class.
To find the asteroids, students studied Internet images of space
that were taken by powerful telescopes at the Astronomical Research
Institute observatory. NASA research scientist Robert Holmes said the
telescopes see stars 10 million times fainter t han the eye.
The project's goal is to protect the Earth from the possible
dangerous impact of an asteroid, Holmes said. NASA has advanced
technology that could alter the path of an identified asteroid, he said.
"This is very important research these students are working on when
you realize, only a decade ago, comet Shoemaker-Levy 9 slammed into the
planet Jupiter," he said. "If the earth had been the target instead of
Jupiter, it would have had devastating results and none of us would be
here today."
Each student was awarded with a plaque for their asteroid find and earned the praise of their teacher, Curtis Greg.
Finding an asteroid in space is like finding "needles in a haystack," Craig said.
For their part, Tholl, McClesky and Karlee Craig say their discoveries hasn't raised their status on the high school campus.
"It is really neat, though," said Spencer Baxter, another student
who worked on the project. "It will make an impact on the scientific
community."
'Meteorite' lands near petrol pump in Hoshiarpur
The Hindu
Wed, 28 May 2008 17:09 EDT
Hoshiarpur (Punjab): A ball of fire came hurtling from the night
skies and fell in a field adjacent to a petrol pump on the
Hoshiarpur-Tanda road here, convincing owner Palwinder Singh that it's
a meteorite.
A month ago, a similar object had fallen in Hotipur village in
Sangrur district, prompting a Geological Survey of India team to visit
the site and examine it.
The unidentified flying object fell in the field in Lachowal area of
the district at 8.45 p.m. on Friday, when the petrol pump staff were
emptying a diesel tanker, setting nearby bushes ablaze. They rushed
there and extinguished it, Mr. Singh told reporters on Tuesday. - PTI
Pilot reports seeing a 'rocket' in mid-air
Anna Brones
Gadling.com
Wed, 28 May 2008 18:28 EDT
Some weird things can happen in the skies. At least if you are the Continental Airlines pilot who reported seeing a rocket fly past his cockpit window while he was about eight miles away from Houston's George Bush Intercontinental Airport, as reported by the Houston Chronicle.
"We don't know for sure what the object was. But we think it might
be somebody doing model rocketing," said Roland Herwig, an FAA
spokesman. "The pilot saw the rocket and some people saw the rocket's
trail (of smoke)."
The incident has turned into a full-blown federal investigation, with both the FAA and the FBI looking into the matter. Fortunately no one was harmed or scathed. Just a little weirded out that a rocket may have flown past the cockpit window.
Possible Sonic Boom in Columbia
Jen Reeves
KOMU.com
Wed, 28 May 2008 16:13 EDT
Boone County Joint Communications says there is no damage reported after a large boom rocked portions of Columbia.
A large boom was felt and heard in many portions of the city a little after 1:00 PM.
Calls to area emergency departments found no answer to the cause of
the noise. The Columbia Regional Airport also did not have any
information about a possible military flight in the area. Boone County
Joint Communication thinks a sonic boom is the most likely cause of the
shaking.
What is the Fastest Spinning Object in the Solar System? Near-Earth Asteroid 2008 HJ
Ian O'Neill
Universe Today
Wed, 28 May 2008 17:56 EDT
A British astronomer has discovered a strange spinning object. The
fact that it is spinning in itself is not strange, but the speed it is
doing so has raised some eyebrows. The near-Earth asteroid 2008 HJ has
been spotted spinning at a rate of one rotation every 42.7 seconds,
breaking the record for the fastest rotating natural object
in the Solar System. It is so fast that it has been designated as a
"super-fast rotator". What makes this discovery even more interesting
was that it was spotted by an amateur astronomer when using the
Australian Faulkes Telescope South observatory, operating it remotely
over the Internet, in his Dorset home in the south of the UK...
 |
| ©Unknown |
Asteroid 2008 HJ smashes the previous record for fastest rotating
object by 35 seconds. The previous record holder was asteroid 2000 DO8
(discovered eight years ago) with a rotational period of 78 seconds.
This new discovery comes from a new project funded by the Science and
Technology Facilities Council (STFC), which gives UK schools and
colleges access to the world-class Faulkes Telescopes based in
Australia and Hawaii. This finding is one of four recent successes in
the search for small near-Earth asteroids under 150 meters in diameter.
In April this year, the first significant discovery by the project was
of asteroid 2008 GP3 with a measured rotation period of 11.8 minutes.
Perhaps even more exciting than the discovery itself is who spotted
asteroid 2008 HJ in the first place. This isn't a news release from the
Australian observatory, it isn't even an announcement from an academic
institution; the discovery was made by retiree Richard Miles from the
comfort of his own home. Miles is an amateur astronomer and
vice-president of the British Astronomical Association (BAA). He was
able to carry out his research via a remote connection to the Faulkes
Telescope South on the other side of the planet, in the UK. This
charity based program enables enthusiasts and students to control the
research-grade two-metre diameter telescopes, and the discoveries are
coming thick and fast.
"A discovery like this demonstrates the capabilities of amateur
astronomers and school students to produce exciting scientific results
if given the right tools. By providing Richard with access to a big
telescope we have smashed the previous record, and opened up the search
for even faster objects to UK amateur astronomers and school students.
This helps to put all that classroom science, maths and IT to real
use!" - Dr Paul Roche, Director of the Faulkes Telescope Project at
Cardiff University, Wales
The finding of the 12×24 metre asteroid appears to be consistent
with near-Earth asteroid theory, and many sub-minute period asteroids
can be expected. It's just that not very many have been discovered as
yet, so with the help of UK schools and amateur astronomers, more can
be expected to be found.
Near-Earth asteroids are a concern for the future of the planet as
there are many Earth-crossing rocky bodies that could cause significant
damage to us on the ground should one come our way. Although the skies
appear clear for now, our knowledge of these rogue objects is very
limited. It is generally understood that these spinning pieces of rock
(often weighing in at thousands of tonnes) are fragments from ancient
collisions in the early Solar System. Projects such as Faulkes have an
obvious advantage in increasing our knowledge in that it opens up
observation time to a vast number of astronomers.
Iowa State University Center Maps Out Asteroid Defense Strategies
Alexis Madrigal
Wired
Thu, 29 May 2008 17:56 EDT
Asteroid deflection is one of those topics that draws an eclectic mix of serious NASA engineers, professors, and crazy people.
To help sort through decades of scientific research and a century of
science fiction, Iowa State university professor Bong Wie is
establishing the first-ever Asteroid Deflection Research Center.
The Center will look at all available technologies that could be
deployed to some day keep a space rock from slamming into the Earth and
ending civilization.
"As of 2008, there is no consensus among professionals which
approach or technology can be actually used when we have to use it,"
Wie told Wired.com. "So, therefore, we created this center to bring the
experts from around the world together to [undertake] open-minded
technical study."
Scientists believe the Earth has been hit several times by asteroids
large enough to radically alter the planet. Sixty-five million years
ago, a 6-mile-wide asteroid struck the Yucatan peninsula creating an
enormous crater and probably leading to the extinction of most life on
Earth at the time, including the dinosaurs. More recently, an 50-meter
asteroid exploded just above the ground in Siberia with the force of
500 atomic bombs, leveling trees for miles around. Given the high
stakes, Wie considers developing a strategy to push an asteroid off a
collision path with Earth to be an underaddressed problem.
"No one is taking any responsibility for this problem," Wie said.
Still, in recent years, the threat from so-called near-Earth objects has received increasing scrutiny. NASA delivered a 137-page report to Congress on detecting and deflecting the objects, and the European Space Agency has planned a mission to intercept and impact an asteroid. The so-called Don Quijote mission plan is animated in the video.
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The NASA report summarizes the current deflection strategies to stop "potentially hazardous objects":
A wide range of deflection options were considered and evaluated.
Perhaps the simplest of these is the kinetic impactor, where a
spacecraft is collided with the PHO to change its orbit so that the
object misses Earth. Detonating a conventional or nuclear explosive as
part of the deflection effort can increase a kinetic impactor's
effectiveness... In addition, a number of "slow push" techniques such
as a space tug also were considered.
The various specific alternatives are outlined in the table from the
NASA report. The new Iowa State center will not focus on a specific
technique.
"We will look at high-energy nuclear options as well as low-energy
gravity tractor options," Wie said. "We are not biased in favor of any
particular technique."
Wie stressed that blowing up or tugging asteroids was technically
feasible. In fact, what seems most unrealistic about asteroid
deflection is the idea that world governments would commit short-term
money to a long-term, low-probability problem, even if ignoring the
problem could have huge potential impacts. That's not exactly the
average politician's M.O
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