13/04/2012 11:24 BST | Updated 20/06/2012 06:55 BST

Mars: 'Life On The Red Planet Is 99% Certain' As 1976 Samples Taken By Nasa's Twin Viking Landers Are Revisited

New analysis of soil samples taken on a Mars mission in 1976 have revealed evidence of life, a report claims.

The samples, collected by Nasa’s twin Viking Mars landers, were initially thought to show proof of geological activity, but not biological evidence.

But new analysis by researchers at the University of Siena and California’s Keck Institute believe the original experiments may have been flawed and that there was proof of microbial life.

“On the basis of what we’ve done so far, I’d say I’m 99 per cent sure there’s life there,” said Joseph D Miller, associated professor of cell and neurobiology at the University of Southern California’s Keck School.

He added: “To paraphrase an old saying, ‘if it looks like a microbe and acts like a microbe, then it probably is a microbe.”

The only organic chemicals identified in soil samples from the Viking landers were chloromethane and dicholormethane – non-biological chlorine compounds believed at the time to have been caused by a contamination from cleaning fluid.

The matter was revisited after a surprise finding in samples returned by Nasa’s Phoenix Mars Lander in 2008 – namely perchlorate.

When perchlorate was added to desert soil from Chile containing organics and analysed in the same manner of the Viking tests, the same compounds identified in the Viking samples were found.

The research was published this month in the International Journal of Aeronautical and Space Sciences