A research team on Johnson Space Centre in Houston has been re-examining a meteorite that hit Antarctica 13,000 years ago, and establish the most compelling evidence yet that the planet once harboured bacterial life. The team says that the microscopic crystals that are found in the rock are almost certainly fossilized bacteria that have lots of characteristics in common with bacteria found on Earth.
“The evidence supporting the chance of past life on Mars has been slowly building up during the past decade,” says David McKay, a NASA chief scientist for exploration and astrobiology.
“This evidence includes signs of past surface water including remains of rivers, lakes and possibly oceans and signs of current water close to or at the surface.”
The debate centres on magnetite crystals found in the meteorite. A study is been carried out in 1996 suggested that they were biogenic - produced by living organisms.
Critics, however, recommended that the magnetite was formed by a chemical process called thermal decomposition.
The new paper uses lots of advanced instruments to refute the critics’ theory, arguing that ancient life remains the most plausible explanation.
“We believe that the biogenic hypothesis is stronger now than after we first proposed it 13 years ago,” said Everett Gibson, a NASA scientist.
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