http://www.newscientistspace.com/article/d...rtian-life.html

NASA’s twin Viking spacecraft may have missed signs of life during their examination of the Martian surface 30 years ago. Researchers now say that the landers’ experiments were not sensitive enough to find life and in any case may not have been able to spot the strange forms that Martian life might take.

I gave the link to the paper, to which PNAS is offering free access, here.

Interesting...will be even more interesting to see what Gilbert Levin will have to say about it.

Still think that positive detection of Martian life (if there is any currently extant) will require a multipronged approach: microscopy, metabolic analysis, and DNA/RNA genome decoding (the latter needed to positively determine non-terrestrial origin). After all, who knows who might've sneezed on Mars 2 just before encapsulation & launch?...