NASA’s Mars Curiosity rover has reminded everyone that curiosity is a virtue not always rewarded justly. On Sept. 19, NASA announced that an instrument on the extraplanetary buggy designed to detect the presence of methane in the Martian atmosphere had found, to a pretty close approximation, none at all. The finding shocked earthling scientists, many of whom had expected to find at least a little CH4 on the surface. Spectrometer measurements made from Earth, and on flybys by earlier Mars probes, had all pointed to the likelihood of small amounts of methane.
Of the data suggesting the possibility of indigenous life on Mars, these methane measurements had probably been the strongest. Most of the methane in the Earth’s atmosphere is created by biological activity, largely fermentation in wetlands or in the guts of larger animals like us. Our planet has a fairly steady “methane cycle,” much like the water cycle, that is mostly dependent on bacteria and their single-celled cousins the archaea. Until Curiosity reported its surprising results, much of the debate between researchers was over whether the methane thought to be on Mars could be non-biological in origin. Now, barring some sort of instrumentation error, it seems that if there are beasties up there, they’re awfully good at holding in their farts.
One must guard against the danger exobiologists call “carbon chauvinism”; extraterrestrial life could conceivably have some entirely different chemical basis, or could involve phenomena at scales yet unimagined by humans. That said, there are very good reasons for carbon chauvinism. Nothing else seems to make as good a building block for the self-reproducing, orderly structures that define life and make it possible. It forms huge, stable molecules that allow for information coding schemes like the DNA double helix. The proposed alternatives to carbon-based life tend to have a fantastic, fairy-tale flavour, given what we know for sure about the relative abundance of the various elements in the universe.
Methane is the simplest of all hydrocarbons, and its apparent absence in the Martian atmosphere is a real blow to those who hoped to find life there. Martian life is not only not making methane; it is apparently not making anything more complex that would break down into methane. Curiosity has more methane tests to perform, and the European Space Agency is sending up a “trace gas orbiter” in 2016. But this test was the experimentum crucis, the high-stakes exam. Methane in a planet’s atmosphere is what one NASA scientist once classified as a “Category II biosignature.” This would have counted as a pretty intense signal in a scheme wherein Category I is basically “The aliens just built a Quiznos and a statue of Michael Jackson.”
We have all been spectators to the Martian takeover of the American space-exploration agenda, such as it is. An insecure America, nostalgic for the frequent research conquests and the peaceable belligerence of the space race with the Soviets, looks with ever brighter eyes toward the next rock out from the Sun. The international non-profit Mars One project, which has a sketchy program for a manned mission in 2023, has found that thousands of people around the world are eager to sign up for what is very likely to be a one-way trip.
NASA, in its quest for a popular, captivating raison d’être, has at times oversold evidence of possible life on Mars nearly to the point of hype. It is hard to foresee what effect the Great Methane Disappointment of 2013 will have on the publicity machine. Like it or not, a major pretext for unmanned data-gathering missions to Mars, missions like Curiosity’s, will have been lost. But it may mean we can go there personally and do whatever the hell we like, in the authentic, arrogant tradition of Western exploration.
Mars is the only convenient laboratory we have right now for exploring alternative origins of life, and some even think earthly life may have originated there before being carried here on bits of rock and dust. If Mars proves to be a dud, we will not be under any obligation to treat it as an irreplaceable nature preserve, any more than we do Earth’s moon—not that we are doing much with that yet. Instead of dreaming of a handful of doomed, miserable one-way colonists munching hydroponic quinoa in an inflatable tent, we could start imagining more ambitious terraforming projects, envisioning how we would change Mars on the grand scale in order to make it more habitable.
Want to hit Mars with nukes to construct underground caves for later occupation? Or seed it randomly with shiploads of our own hardy “extremophile” micro-organisms and see which ones thrive? Let’s go for it! Nobody’s using it! Maybe the party’s just getting started.