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Life on Mars?

© Robert Davis

In recent days and as we speak, there have been and continue to be some rather dramatic developments in the matter of whether there ever was, or may be now, life on Mars.

Scientists of the European Space Agency were discussing the findings to date of their Mars Express mission, and many of them have become fairly unequivocal in asserting that Mars once harbored bacterial life (bacteria at the very least), and may indeed continue to do so. Ever since the Mariner missions and the negative results of the Viking probes, the idea of current life on Mars has seemed out of the question except to a few hardy individuals drawing inspiration from the most extreme environments on Earth. Yet new evidence continues to point not only to there having very likely been past life on the Red Planet, but also to the nontrivial possibility that life may continue to exist there at present.

For one thing, Mars Express has discovered an equatorial ice deposit some 800 km x 900 km in size that would have been formed within the last 5 million years. In other words, ladies and gentlemen, we've got water on our hands--and in geological terms, extremely recently liquid water at that--and as the biologists have always told us, "Water = Life." Mars Express investigators also believe that whether the volcanic activity that would have sustained underground liquid water at the equator 5 million years ago is still going on; similar processes are probably still active at the Martian North Pole. The Mars Express results do not support the idea of liquid water on the surface of Mars any time within the last 3 billion years, however, though this may not agree with the findings of NASA's Spirit and Opportunity rovers.

They have also detected methane in the Martian atmosphere, which previously had been thought to be lacking (In contrast to Saturn's moon Titan, which is swimming in it.). What's more, they have discovered that the quantity of methane is, to repeat an earlier turn of phrase, nontrivial. That is to say, it exists in such quantites that some among the ESA scientists argue it is likely the byproduct of biological processes. For a bit of whimsical context, consider that the typical Earth cow belches methane four times each minute. Perhaps Martian bacteria are doing something similar. (Presumably there are no titanic Titanian Guernseys responsible for that moon's atmosphere.)

In the end, an informal poll of the scientists attending the conference where these results were being discussed revealed that three-quarters of them thought there had once been life on Mars, and one-quarter further thought that there was life there now.