Scientists have discovered compelling new evidence that life has existed on Mars and was brought to Earth in an ancient meteorite.
State-of-the-art instruments and techniques suggest that tiny fossils in the rock found in Antarctica are microscopic aliens and not produced by other effects.
The meteorite found in the Antarctic's deep freeze is called Allan Hills 84001. It hit the headlines 13 years ago in 1996 because of the peculiar fossils it appeared to contain.
NASA suggested then that it was ancient martian microbial life and President Clinton even went on TV to speak to the nation about the historic moment. However, the majority of scientists were unconvinced.
The meteorite, blasted out of the martian surface 16 million years ago, crashed to earth about 13,000 years ago and lay undetected in the icy desert.
Now a new report by NASA scientists at their Johnson Space Centre in Houston says there is powerful new chemical and fossil evidence that the meteorite does indeed contains microscopic martian microbes.
The new research uses more advanced high resolution electron microscopy than was possible 13 years ago. The scientists have examined carbonate discs and tiny magnetite crystals inside the space rock.
The report by the NASA team, led by Kathie Thomas-Keprta, claims that the carbonate disks that are evidence of interaction with water on Mars more than 3.5 billion years ago.
The scientists believe this means the rock formed at a time called the Noachian epoch when vast oceans may have covered Mars and the planet was much more like Earth than the dusty desert it is today. Other scientists have suggested that life could have survived at a time when Mars was warmer.
The NASA team's report says that magnetite fossils "with unusual chemical and physical properties" in the meteorite are "intimately associated within and throughout these carbonate disks".
They believe this is clear evidence that the fossils are microbes from Mars and not bugs from Earth that contaminated the rock in the last few thousand years.
The new findings appear in a 46-page scientific paper being published this month in the respected journal of the Geochemical and Meteoritic Society
Spaceflight Now says the new research centres on so-called magnetic bacteria that on Earth, and apparently Mars as well, leave distinctively-shaped remnants in the rock. Chemical tests also show they are likely to be a biological feature rather than geological.
UK Mars expert Professor Colin Pillinger, of the Open University, told Skymania News: "This is valid, good quality work and more compelling evidence to add to the mix."
"it has been too easy for others to claim they were due to something else. But these guys have been plugging away at this for years and years. It is a very careful study by some very reputable people.
"If you want to prove that there is life on Mars you have to have extraordinary proof. That's why we wanted to go there with Beagle."
Impact expert Dr Emily Baldwin, Deputy Editor of Astronomy Now magazine, told us: "Many scientists argued that what looked like fossils in the meteorite were really caused by the explosive event, such as an asteroid impact, that blasted the rock out of Mars in the first place.
"But the NASA team is now saying they have proved that they could not have been produced by the blast itself.
"If indeed the features turn out to have an extraterrestrial biological origin, and were not formed during the 13,000 years that the meteorite spent lying on the surface of the Earth, then this will have profound implications for our understanding of how life evolved in the Solar System."
Picture: The ALH84001 meteorite being examined in the laboratory. Credit: NASA.
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