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Do NEOs provide evidence for life on Mars?
In 1996 NASA scientists reported the presence of tiny structures with a martian meteorite ALH 84001 which they suggested might be fossilised bacteria.
The meteorite was a small NEO that was blasted off the surface of Mars by the collision of an asteroid or comet and eventually fell in the Antarctic. Extensive studies of martian meteorites, however, reveal that many contain live terrestrial bacteria which can be quickly fossilised on Earth. Furthermore the structures found in ALH 84001 lack features such as cell walls to prove they are fossil organisms and are smaller than similar fossils found on Earth.
Most scientists believe that, as yet, no conclusive evidence has been found in meteorites for extant or extinct life on Mars. However, the presence of abundant water ice in martian soil, as determined by NASA Mars Global Surveyor, and evidence that liquid water flowed on the surface in the geological past suggest that living organisms could have evolved on the planet.
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