Eos Chasma
Posted on 09/16/2005 9:44:14 AM PDT by LibWhacker
The original home of the world's most famous space rock, the Allen Hills Martian meteorite, has now been identified, thanks to data from the orbiting spacecraft Mars Global Surveyor and Mars Odyssey and a better understanding of cratering dynamics.
The rock, called ALH84001, has been the subject of intense study ever since 1996 when scientists from NASA's Johnson Space Center startled the world by reporting that fossilised microbial life might be embedded inside it. The rock, which formed at the very dawn of the solar system 4.5 billion years ago, was blasted from the surface of Mars around 17 million years ago by an impact and made its way to Earth, landing in Antarctica.
While the claim remains highly controversial, the JSC scientists say further study has bolstered the evidence for fossilised life in ALH84001. So the discovery of the rock's place of origin on Mars could make that spot a strong candidate for a future landing by robots or people searching for extraterrestrial life.
The analysis, based on the rock's mineral characteristics, was presented by Vicky Hamilton of the University of Hawaii at this week's meeting of the Meteoritical Society in Tennessee, US.
Perfect match
Hamilton looked for matches between the laboratory spectrum of the meteorite, a mix of orthopyroxene and basaltic minerals, and data from the Thermal Emission Spectrometer and other instruments on the orbiters. "There was only this one place, in all the places we can look that aren't too dusty, that had a composition that was consistent with the ALH84001," Hamilton told New Scientist.
The site is in the Eos Chasma, a branch of the enormous Valles Marineris canyon system. Hamilton has examined it further using topographic and thermal data and high-resolution imagery. "Putting this all together, it's all consistent with this being the source region," she said.
The pinpointed area is a “lobate flow”, the kind that occurs when an impacting object strikes a fluid-rich soil, as is the case with many Martian craters. There is a crater about 20 kilometres in diameter there, which cratering studies have now shown indicates a large enough impact to eject the rock out of Mars' gravitational field.
There is no single "smoking gun" piece of evidence that proves this was the place the meteorite came from, Hamilton concedes: "There isn't any piece of information that makes this a unique interpretation, other than the fact that we haven't seen any other suitable places."
Fascinating picture
Everett Gibson, one of the JSC scientists behind the original findings of possible signs of life in ALH84001 says the picture put together by Hamilton is "fascinating”. And like his work, there was “no single line of evidence that says, ‘ah, this is it’," he notes.
The meteorite is believed to have first formed deep beneath the Martian surface, and was later transported to the shallow depth from which it was propelled into space.
The Eos Chasma location fits that. The 4-kilometre-high cliffs bordering the canyon have exposed rocks from various ages in the Martian past, and impacts or erosion could have brought the rock to the canyon floor - along with rocks from a major portion of Mars' history.
That makes it a prime site for a landing mission someday, Hamilton said. It would be an opportunity to sample rocks from a wide variety of ages, all in one place. And, if it really is the launchpad from which ALH84001 began its interplanetary travel, it may also be the place where the mystery of whether the rock's unusual contents really are signs of ancient life is finally unravelled.
Apparently, added the astronomer, the meteorite originated only a mile from the birthplace of Senator John Kerry...
Came from a region that might have been wet at the time, looks like. That makes the possibility of fossil life forms reasonable.
It's Bush's fault that Mars experienced global warming several million years ago. He SHOULD have signed that Kyoto Treaty!!!!
"Yes, Virginia, there is a home for the moonbats."
Maybe they can use that thing to find Osama bin Laden on this planet?
So they started with the assumption the meteorite came from Mars, and then said it came from THIS spot simply because "we haven't seen any other suitable places." ???
Is that the scientific method?
It was more than an assumption. The composition matches Mars in general rather than earth.
That's a big CHASMA!............
But but, aparently nothing exploded,(a black hole in nothing none the less) creating a gas cloud for billions of years first, so no rocks were even formed at the 'dawn of the universe', so the timeline doesn't fit, plus it contradicts the BBT event explanation.
Amazing how that "rock survived intact, never burned up in earth atmosphere, or broke up into billions of bits on impact.
Than in itself is very strange. Or a better explanation is this is all moonbat garbage.
Now how can that be? Mars and earth were all formed from the same material according to the BBT.
This is old news. It was originally reported when the rock was found about a year ago.
Meteorites survive intact all the time.
With all due respect, you need to be a rocket scientist to participate fully in this discussion. Our planetary probes have shown that every planet has a unique "signature" of various isotopes in specific percentages. That's the STRONG EVIDENCE that the ALH meteorite came from Mars. This new hypothesis, that the meteroite came from a specific location on Mars, is simply that...a hypothesis that needs more evidence. BTW, the BBT does not state that all planets are made of exactly the same stuff. It is obvious that there were mechanisms at work that differentiated the composition of each celestial body. Furthermore, current generally accepted theory is that the universe is many billions of years older than the Solar System. With the Scientific Method, the best system ever devised to determine Truth, hypotheses and theories are accepted or rejected based on objective proof and data. Belief has nothing to do with it.
I think she should have a one way ticket to go find that flag.
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