The day the first Viking lander touched down on Mars is still fresh in my memory, particularly the early confusion about the real color of the Martian sky (which had seemed, by data misinterpretation, to be a rich blue). Then the excitement about possible life through experiments combing through the top few inches of Martian soil. Bob Schieffer announced there may be life on Mars — “no fooling”, said Schieffer with a delighted grin — on CBS news not long after, but later studies discounted the one experiment that might have detected biological activity.
Gil Levin, the scientist in charge of the disputed Viking experiment, still thinks it was successful. But other experiments could find no organic molecules in the Martian soil, an assumed prerequisite for life. Now a new paper argues that the Viking methodology was flawed. In fact, similar experiments don’t even find organic molecules in the Atacama Desert between Chile and Peru, where dry conditions seem conspicuously Mars like, and where experiments on remote life detection have continued at a robust pace. Yet updated testing reveals carbon at these sites.
And Rafael Navarro-González (National Autonomous University, Mexico) says in the new study that if the Viking scientists had known these results thirty years ago, they would have interpreted Viking’s work differently. Which is not to say that Viking detected life, but that we can’t discount organic molecules in the soil, which probably houses 1,000 times as many organic molecules as Viking data suggested.
Add to that finding Neill Reid’s recently published work on one-celled organisms from Antarctic lakes and we’re talking about living things in conditions that mimic what we should find on Mars. So let’s not rule Mars out; if bacteria can live almost two miles below the Earth in a South African gold mine, their presence tells us not to be too doctrinaire about what we consider a habitable environment.
The Wall Street Journal‘s fine science correspondent Sharon Begley goes still further in her latest entry:
Something else improves the odds that we are not alone: the building blocks of life are nearly as common in interstellar space as beer at ballparks. In August, astronomers announced they had found eight new biologically significant molecules deep in the giant clouds of gas and dust that spawn planets.
Although names like “methyl-cyano-diacetylene” might not evoke visions of whales or roses or other living things, these carbon-based molecules are the precursors to life. The new octet brings to 141 the number of different organic molecules found in interstellar space, all of which fall onto the surface of planets like seeds.
A universe seeded with life sounded preposterous not so long ago. Now the notion is gaining plausibility. It may take, as Gregory Benford reminds us, human feet on the ground on the Red Planet to conclusively make the call for Mars, but when and if we do find life there, the odds on other abodes in our own Solar System — and certainly around other stars — go up as well.