Martian Life: The NASA Cover-Up?

"What we've shown with the MOD is that you can detect amino acids with very high sensitivities. And using the detection limits of what the Viking GCMS measured for these compounds, and comparing it with our instrument, we estimate that Viking would have missed on the order of thirty million bacteria cells per gramme of soil. So there could have been cells in the soil, but the Viking GCMS wouldn't have seen them."

Oliver Botta reminds us how much our knowledge about the tenacity of life in extreme environments has advanced since Viking. "The problem with the biology package on Viking was that it was really designed to look for terrestrial analogues of life. And we have to realise that, in the Seventies, we didn't know of the variety of lifeforms we have on Earth - high temperature, low temperature, and high acid, or whatever".

Extremophile expert Jonathan Trent of NASA's Ames Research Center can even contemplate life in an environment of hydrogen peroxide. "Cells on Earth have wonderful adaptations for getting rid of peroxide. For example, there's an enzyme called catalase. When you have a wound, and put peroxide on to sterilise it, the peroxide will bubble. The catalase is transforming the peroxide into water and oxygen, and the bubbles are actually oxygen coming off. Many organisms produce catalase, and it isn't inconceivable that they could cope with the peroxide levels on the surface of Mars".

So where does the jury stand these days on the Viking life findings?

CREDIT: Hencoup Enterprises Danny Glavin (left) and Oliver Botta check out samples of meteorites for organic molecules: they hope similar equipment will discover the materials of life on Mars.

David Wynn-Williams is a geologist at the British Antarctic Survey. "When Gil Levin evaluated his system in the Antarctic, he was able to show biological activity at very low densities of micro-organisms. So he's partly right - the GCMS was not as sensitive as his system, but I need more evidence to be convinced that he did actually see microbiological activity on Mars".

'Mr. Mars', NASA-Ames's Chris McKay adds: " If Gil's experiment was the only experiment we had, its results would be consistent with a biological source. But it was inconsistent with the other experiments. Explanations relying on a chemical reaction with the soil are more plausible, but I should say that none of these explanations have been proven".

NASA's John Rummel remembers how Viking's non-detection of life cast a shadow over the Agency. "When I first got to Headquarters with the odour of what was assumed to be a negative result on Viking, there were many astrophysicists quite willing to prove to me that life couldn't exist anywhere in the Universe, including the Earth - and at days in Washington, I agreed with them".