Note: a couple of news sources have posted about this topic * and have made somewhat misleading claims about it. Let me be clear: No one is claiming they found life on Mars. The idea here is based on speculation of life on Mars, and what it would mean for the tests we use to look for it. Got it? No one has found life on Mars. Yet.
Chris Bjornberg/Science Source/Photo Researchers, Inc.
Some interesting news out of the European Planetary Science Congress 2007 being held currently in Potsdam.
In 1976, the US put the first two landers on the surface of Mars. These Viking probes were designed to look for the presence of life on Mars in three different experiments. Two of the results were negative, and one, which looked at gases released when martian soil was incubated, was maddeningly inconclusive.
Two scientists (Joop Houtkooper of the University of Giessen, Germany, and Dirk Schulze-Makuch from Washington State University) have re-examined the results, and they speculate that an odd form of life could explain the third experiment's results.
Imagine a microscopic bug of some sort that was based not on water, but on a mixture of water and hydrogen peroxide. When heated, they could produce the levels of oxygen and carbon dioxide seen in the experiment -- in fact, the scientists calculate that if the soil is made up of 0.001 by weight of these little critters, it would explain the results tidily. Moreover, the H2O2 would act as a type of antifreeze, allowing the bugs to stay alive in the martian cold.
Do I buy this? Is Mars covered in little flagella with bottle-blond cilia? Well, no, I don't. The evidence is circumstantial, of course, but it's still pretty interesting. The question is, is it interesting enough that we should design experiments on future missions to test for this kind of life more aggressively? That depends on how well received these results are, how difficult it would be to test for this kind of life, and the biggie, how much it would cost.
Earth is a pretty congenial place for water-based life, and there's no real reason to assume all life must be like us; in fact, when life first arose on Earth it was nothing like us -- and I don't mean bipeds with a penchant for reading blogs and starting wars based on superstitions. I mean they weren't even oxygen-based; they grew up to use chemicals like ammonia and methane. Oxygen-users evolved later as O2 was created as a waste product of the earlier life.
We breathe some other long-dead species' pollution.
So who's to say what other kinds of life there are out there? We haven't even sampled all of ours here on Earth yet, and we have some weird stuff going on right here. I don't know if peroxide-based life is plausible, possible, or inevitable, but maybe, just maybe, it's worth a look.
*These two news sources also appear to have broken the midnight GMT embargo (a demand not to release the news by news agencies until that time). This is IMO very skeevy of them.