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New discoveries raise hopes, questions about life on Mars BY JEFF FOUST SPACEFLIGHT NOW Posted: January 17, 2002 Two separate studies published Thursday both provided new evidence that life could exist on the planet Mars while raising questions about the validity of some of the evidence presented for Martian life. One paper, published in the latest issue of the journal Nature, discussed the discovery of a microbe living deep within the Earth in conditions that resemble those below the surface of Mars. The microbe, found 200 meters below the surface in the mountains of Idaho, are completely cut off from the Earth's ecosystem, thriving in conditions like those on the early Earth, and perhaps within Mars or other worlds. "The microbial community we found in Idaho is unlike any previously described on Earth," said Derek Lovley, head of the microbiology department at the University of Massachusetts, Amherst, and one of the authors of the Nature paper. "This is as close as we have come to finding life on Earth under geological conditions most like those expected below the surface of Mars." Unlike other subterranean life, which survives on organic material carried underground by groundwater seepage, the microbes discovered in Idaho instead exist by combining hydrogen and carbon dioxide gasses dissolved in water to produce methane, releasing energy needed to sustain life. The microbes don't require organic carbon or sunlight to survive. Such "Archaean" microbes were likely commonplace on the Earth early in its history, when hydrogen was commonplace but other organic compounds were not. The existence of the microbes also raises the possibility that such life forms could exist on other worlds, in similar conditions. "On Mars and other planets or moons in our solar system on which life might exist, liquid water is only available below the surface where there is no sunlight," said Lovley. "So, if there is life, it must sustain itself with alternative energy sources. This study demonstrates, for the first time, that certain microorganisms can thrive in the absence of sunlight by using hydrogen gas released from deep in the Earth's surface as their energy source." Mars is the most likely world in the solar system, other than the Earth, where life could have taken root and might still exist today. One controversial piece of evidence for past life on Mars were carbonates found in Martian meteorite ALH84001, first reported over five years ago. However, a separate paper published in Nature suggests that those carbonates may not have an organic origin. Studies by European astronomers, using ESA's Infrared Space Observatory, have turned up evidence of carbonates in two nebulae formed by dying stars. Those carbonates, astronomers say, could not be formed by water, as scientists previously believed was the only way to create them. "The amount of carbonates we find is equivalent to at least 30 Earth masses, far too large to be the relic of a hypothetical planetary system present before the star became a planetary nebula," said Ciska Kemper of the University of Amsterdam. "On the other hand, the age of the dust shell in the nebula is about ten thousand years, which is too short for a new planetary system to form." This implies that the carbonates were formed by another method, although scientists haven't determined what that could be. It does mean that the existence of carbonates is alone not evidence of water, so the discovery of carbonates in a meteorite does not mean that it has been exposed to water, as was assumed for ALH84001. It may also mean that earlier beliefs that liquid water was available within 20 million years of the solar system's formation, based on the discovery of carbonates in other meteorites, may have to be reexamined.
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Women Astronauts Learn about women astronauts,what they do, and how they got to where they are today. Read their story and how attitudes towards women in space changed.Apollo 12 tribute DVD set ![]() New! Featuring the jovial crew of Pete Conrad, Dick Gordon and Alan Bean, the Apollo 12 mission was struck by lightning shortly after liftoff but proceeded on the second successful exploration voyage to the lunar surface. This three-disc DVD brings the mission to life with extraordinary detail. U.S. - U.K. - E.U. - Worldwide Fallen Heroes special patch This special 12-inch embroidered patch commemorates the U.S. astronauts who made the ultimate sacrifice, honoring the crews of Apollo 1, Challenger and Columbia.U.S. - U.K. - E.U. - Worldwide Women in Space Women of Space: Cool Careers on the Final Frontier is for girls, young women, and anyone else interested in learning about exciting careers in space exploration. Includes CD-ROM.U.S. - U.K. - E.U. - Worldwide Mars rover poster This new poster features some of the best pictures from NASA's amazing Mars Exploration Rovers Spirit and Opportunity.U.S. Apollo 11 special patch Special collectors' patch marking the 35th anniversary of the historic Apollo 11 moon landing is now available.U.S. - U.K. Expedition 18 patch & pin The official embroidered patch and lapel pin for the International Space Station Expedition 18 crew is now available to from our stores.Ares patch The Ares Project will develop two new rockets to launch astronauts back to the Moon under NASA's Vision for Exploration. The Ares 1 will employ a single space shuttle solid rocket booster to loft the Orion crew capsule. The gigantic Ares 5 will haul the equipment and cargo needed for such lunar voyages. This is the Ares emblem.![]() Apollo patches The Apollo Patch Collection: Includes all 12 Apollo mission patches plus the Apollo Program Patch. Save over 20% off the Individual price. U.S. STORE Columbus mission patch The official astronaut embroidered patch of Atlantis' STS-122 mission that launched the Columbus science lab in February is available to U.S. customers from our store.Get e-mail updates Sign up for our NewsAlert service and have the latest news in astronomy and space e-mailed direct to your desktop (privacy note: your e-mail address will not be used for any other purpose). Station Calendar
NEW! This beautiful 12" by 12" wall calendar features stunning images of the International Space Station and of the people, equipment, and space craft associated with it, as it takes shape day by day in orbit high above the Earth. |
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