Reports: Mars meteorite has no signs of life
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LITTLE ROCK, Ark. (AP) - Scientists were mistaken when they thought a rock in Antarctica contained evidence suggesting life on Mars, according to three papers in a journal about meteors.
One article to be published today in Meteoritics and Planetary Science at the University of Arkansas says non-Martian rocks showed the same "evidence" of life. The other articles say temperatures were too high for tiny bacteria to form and leave organic evidence in the nooks and crannies of the 4.5 billion-year-old, potato-sized rock in Antarctica.
In 1996, 15 researchers reported that crevices in a meteorite named Allan Hills 84001 contained organic molecules called polycyclic aromatic hydrocarbons, or PAHs. Also present were magnetite and iron sulfide, chemicals that can be related to bacterial action.
Highly magnified pieces of the meteorite also revealed what appeared to be the fossils of "filamentous bacteria."
"If these are really Martian in origin and they are biological, the first test would be if there are similar objects on lunar meteorites," said Derek Sears, the journal's editor. The lunar meteorites shouldn't have the same objects because there's no life on the moon, Sears said.
"Within an hour of looking at the lunar meteorites, we knew," Sears said. "We found objects on the lunar meteorites that we cannot distinguish from the Martian meteorites."
The initial researchers said the PAHs were in a solution that oozed into the rock's cracks -- at low temperatures -- after the rock was formed.
However, Ed Scott of the University of Hawaii said, evidence showed that the carbonate materials were present when the rock was created and, as either a vapor or a very hot fluid, became integrated with the rock before it cooled.
A study led by John Bradley of MVA Inc. of Norcross, Ga., also concluded that iron oxide crystals found in the Martian meteorite also would have formed at temperatures too high to support life. Similar crystals have been found in volcanoes on Earth, and their formation has been attributed to condensation at temperatures eight times higher than that of boiling water.
Allan Hills 84001 is the oldest of 12 known meteorites that are thought to have been jolted from Mars by a massive impact and left drifting in space until they fell to Earth. The rock is thought to have been knocked from the Martian surface with a glancing blow about 15 million years ago and then landed on the Antarctic ice sheet about 13,000 years ago. It was discovered in 1984.