London, November 28 (ANI): Scientists studying a chunk of Mars rock that was found in Antarctica in 1996, have determined that it may show signs of life, in the form of fossilized microbes.
In 1996, David McKay of NASA's Johnson Space Center in Houston, Texax, and colleagues proposed that that a chunk of Mars rock found in Antarctica, called ALH 84001, contained possible signs of past life on the Red Planet, such as complex carbon-based molecules and microscopic objects shaped like bacteria.
Many researchers doubt the claim, however, and various suggestions have been made for how the structures could have been created without life.
One area of disagreement centred around nanocrystal magnetites in the rock, some of which appear to have chemical and physical features identical to those produced by contemporary bacteria.
Skeptics of the biological explanation suggested that the magnetites were created when carbonate decomposed under high pressures and temperatures, perhaps in the heat of the impact that ejected the meteorite 15 million years ago or deep beneath the Martian surface.
Now, according to a report in New Scientist, a fresh analysis by McKay and colleagues rules out the carbonate decomposition explanation.
The researchers have used high-resolution electron microscopy not available 13 years ago to study the physical and chemical make-up of the magnetites in detail, and found that no plausible geological scenario could explain the carbonate decomposition origin.
Dennis Bazylinski at the University of Nevada in Las Vegas told The Times, "Until now, I was on the fence, but this paper has really thrown out the non-biological explanation."
The possibility that the rock contains fossilised microbes received another boost in August when a team led by Paul Niles, also of NASA Johnson, showed that carbon in the meteorite was deposited in balmy water conducive to life, rather than a scorching temperature above 150 degree Celsius as had been proposed previously. (ANI)