Why the Phoenix lander could miss life on Mars

What a balls up. When NASA sent Viking to look for life on Mars more than 30 years ago, the one experiment that could identify lil green bugs came up trumps: it produced an overwhelmingly positive result. That’s when the trouble started. Another experiment had found no evidence for organic molecules so, with the eggheads all a-tremble, NASA declared the result null ‘n’ void.

Now NASA looks set to repeat the confusion.

Since Viking, them astrobiologists at NASA have been a-ponderin and a-plottin how to do the experiment properly. And right now they got a spacecraft called Phoenix on its way to Mars with the equipment that they built to spot what they thought was the characteristic chemical signature o’ life.

But Chris “Hochai” Mackay, an astrobiologist at NASA Ames in California, and a few buddies have carried out one of the Phoenix experiments on Earth. And it looks as if Phoenix is gonna produce the same kinda ambiguous results that plagued Viking.

Here’s some background for ya. The famous Viking life-on-Mars experiment mixed some nutrients laced with C-14 into the Martian soil. Everybody agreed that if the mixture cooked up C-14 methane then that would be an unambiguous sign of life cos nothing but life can make methane outta these nutrients.

But when C-14 methane turned up, NASA changed tack and said it musta been made by something else, probably some powerful oxidising agent in the soil such as hydrogen peroxide. So the Mars Phoenix lander which is due to touch down on the Red Planet next May is specifically designed to look for high concentrations of hydrogen peroxide.

But earlier this year, a couple o’ upstarts from the Justus-Liebig-University in Germany pointed out that some organisms on Earth produce hydrogen peroxide and that it’s just possible that life on Mars might thrive on it. So detecting hydrogen peroxide won’t tell ya nothin about whether or not life on Mars exists.

But by then NASA was polishin’ the wing mirrors on ol’ Phoenix which was all but ready to fly. So there was no chance of modifyin the experiment to take the new ideas into account.

So them NASA bods started a-thinkin’ and a-ruminatin’ about what else Phoenix could look for that might settle the question. One possibility is that the hydrogen peroxide would have to be stabilised by another chemical to prevent it reeking havoc within any Martian cells. So perhaps Phoenix could look for the tell tale signs of the stabiliser.

To find out, Hochai Mackay and co simulated the tests by copyin the Phoenix experiment to go a-huntin and a-searchin for the stabiliser on Earth. They say their results indicate that if the stabiliser exists in large quantities (in excess of 3 per cent of the mass of the soil) Phoenix should spot it. If it exists in lower quantities, which it almost certainly will, then Phoenix won’t spot it.

So the bottom line is that Phoenix can’t tell a one-eyed Martian succubus from a bottle top. Back to the drawing board, boys ‘n’ girls. The rest of us might as well get ready for one almighty damp squib when Phoenix arrives next May.

Ref: arxiv.org/abs/0710.1036: Testing the Hydrogen Peroxide-Water Hypothesis for Life on Mars with the TEGA instrument on the Phoenix Lander

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