Aviation Week & Space Technology, 03/20/2006, page 28

Craig Covault, Houston

New research supporting a hypothesis that primitive microbial life forms existed on Mars during very recent geologic time--or may still exist--will raise new controversy about the possibility that evidence of life is preserved in Martian meteorites recovered on Earth.

The findings were presented at the 37th Lunar and Planetary Science Conference (LPSC) by members of the team that 10 years ago garnered presidential attention when they reported evidence of microbial life in a more ancient 3.6-billion-year-old Martian meteorite (AW&ST Aug. 12, 1996, p. 24).

"If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered," President Clinton said then. The jury is still out as to whether what has been detected is indeed evidence of life--but more evidence has now entered the court of scientific opinion.

The team that made the recent and previous findings is headed by David S. McKay of the NASA Ames Research Center and includes geologist Everett K. Gibson of the Johnson Space Center and other researchers in the U.S., France and the U.K. Colin Pillinger, who headed the ill-fated British Mars Beagle lander project, is also on the team.

According to Gibson, the new findings made in the relatively young Nakhla meteorite from Mars reinforce the evidence reported in 1996 that the much older Allan Hills Martian meteorite carried to Earth organic compounds and life-related mineral features.

McKay, Gibson and eight other international scientists presented the data here, arguing that "a plausible basis for hypothesis" is that carbonaceous material found in the Nakhla meteorite "is biogenic." The researchers believe the meteorite--which fell as multiple pieces in the town of Nakhla, Egypt, in 1911--carried to Earth evidence of microbial life that existed on Mars as recently as 650 million years ago.

This places potential Martian life much closer to the present day than earlier data postulated by the Allan Hills meteorite, which argued for life on Mars--but billions of years earlier, during a different phase of the planet's evolution. The new evidence indicates primitive Martian life could be a more recent or even current occurrence.

In a sample of the meteorite held by London's Natural History Museum, the researchers found a carbon-rich substance filling cracks within the rock. The material resembles that found in veins apparently etched by microbes in volcanic glass from the Earth's ocean floor. Initial measurements suggest that the carbonaceous material did come from Mars and is not contamination from Earth.

The new Nakhla data is supported by a separate group of researchers who also presented here a technique called NanoSIMS to find evidence of microbial life in ancient Earth geology. The technique uses a form of ion mass spectrometry to achieve sub-micron resolution for the distribution of organic elements signifying traces of life in rock. It has detected ancient life forms in Earth rock older than about 600 million years. NanoSIMS was used on the Nakhla meteorite and is cited as part of the evidence for its containing evidence of life on Mars.

In addition to the meteorite news, a different European/U.S. team also cited European Mars Express and NASA Mars Global Surveyor imagery indicating potential geothermal activity on the eastern flanks of the giant Martian volcano Olympus Mons could be a long-term habitat for Martian microbial life (see photo). Yet another ESA Mars Express team reported that reanalysis of earlier Mars imagery--seeming to show dust-covered icebergs or pack ice--affirms, with new evidence from the spacecraft, that the ice fields could have dimensions equivalent to the North American Great Lakes.