Life on Mars? Maybe We Missed It

Oct. 24, 2006 — -- Thirty years ago, the first robot probes from Earth landed on Mars, scooped up soil, and generated a wave of excitement -- which quickly died.

The Viking landers carried miniature laboratories. They fried Martian soil samples to see if there were telltale signs of life in the vapor that was created. The first results were tantalizing, but soon the consensus was that Viking had found nothing.

Or so it seemed. Now a team of Mexican scientists has gone back and re-examined the Viking experiment. Their conclusion: no saying yet whether there's life on Mars -- but if there is, we probably missed it.

Viking's experiment "may be blind to low levels of organics on Mars," write Rafael Navarro-Gonzalez and several fellow researchers in this week's edition of "Proceedings of the National Academy of Sciences."

To prove their point, the scientists repeated the test on soil from some of the most desolate places on earth -- the Dry Valleys of Antarctica, and the deserts of Chile and Libya.

The remarkable thing about such places is that despite blazing sun, frigid nights, and little moisture, they are home to living things. When a few minimal conditions are met on earth -- light or other energy, and at least a little bit of liquid water -- life thrives.

Not according to the Viking experiment. If Martians had sent it on a probe to land in Libya, it would have reported no life here.

For the record, the experiment in question was called "TV-GC-MS" -- short for Thermal Volatization-Gas Chromatography-Mass Spectrometry. It literally vaporized Martian soil samples, then examined the gases that resulted to see if there were telltale signs of organic molecules.

Another experiment looked for signs of slightly radioactive carbon, which would be another sign of life. It found there were a lot of chemical reactions going on in the soil Viking scooped up with its robot arm. But for lack of results from the TV-GC-MS experiment, most scientists concluded Viking had some up dry.