Martian Fossils On Earth: The Story of Meteorite ALH 84001
France on October 3 1815 and was designated chas signite Later other nakhlite meteorites were found in Lafayette Indiana in 1931 and in Governador Valadares Brazil in 1958 Together the shergottite nakhlite and chassignite meteorites are known as SNC meteorites Meteorite ALH 84001 was first identified incorrectly incorrectly as a rare form of another mineral family the diogenites In 1993 meteoriticist meteorite scientist David Mittlefehldt caught the error He announced that meteorite ALH 84001 was the tenth known member of the SNC class Scientists now know of well over 100 SNC meteorites Those rare rocks are very special indeed for scientists now believe that the SNC meteorites are pieces of the planet Mars On August 7 1996 meteorite ALH 84001 became the most famous rock on Earth That day a team of scientists led by David S McKay of JSC made an astounding announcement They believed that meteorite meteorite ALH 84001 contained chemical evidence and fossils of ancient Martian microbes Life may have begun on Mars at about the same time as on Earth
2 HOW WAS METEORITE ALH 84001 DISCOVERED Who would want to live for months in Antarctica where it snows even in the summertime Thousands of scientists from around the world that’s who Among them are the researchers of the Antarctic Search for Meteorites ANSMET project Although meteorites are no more likely to fall on Antarctica than on other places they are much easier to find there And the meteorites found in Antarctica are in better condition
In December as the Antarctic summer begins ANSMET scientists mount their snowmobiles and go looking for dark rocks standing out against the ice When they find one they examine it carefully If it is similar to normal Antarctic rocks they leave it alone It probably came loose from some nearby hillside It almost surely moved with the slowly flowing Antarctic ice sheet for hundreds or thousands of years until by chance it became visible in an area swept free of snow by a steady Antarctic wind
But if the rock is different then the scientists wonder wonder where it came from Was it put there by a person No The only people who have ever inhabited Antarctica live and work in scientific research stations Was it put there by an animal No The only animals that spend part of their lives on land in Antarctica are seals penguins and a few other creatures that are never far from the shore of the Antarctic Ocean No other animals have lived on that frozen continent for millions of years So what’s left Did it fall from the sky If the rock has an odd shape and a glassy surface it almost surely did just that It is probably a meteorite The ice of Antarctica makes it easier to find meteorites meteorites and the climate there protects them In other parts of the world weather conditions such as rain and wind can change the surface of the meteorite meteorite The changing seasons can also damage it In warm months water finds its way into cracks in the rock
