Have the Mars landers not only failed in identifying signs of life on the red planet, but also accidentally been destroying them all along? Scientists are beginning to suggest that may be the case. Oops.
According to New Scientist, there's a possibility that we may have been... cooking... the evidence of Martian life all along:
[L]ast year, NASA's Phoenix lander... stumbled on something in the Martian soil that may have, in effect, been hiding the organics: a class of chemicals called perchlorates.
At low temperatures, perchlorates are relatively harmless. But when heated to hundreds of degrees Celsius they release a lot of oxygen, which tends to cause any nearby combustible material to burn. For that very reason, perchlorates are used in rocket propulsion.
The Phoenix and Viking landers looked for organic molecules by heating soil samples to similarly high temperatures to evaporate them and analyse them in gas form. When Douglas Ming of NASA's Johnson Space Center in Houston, Texas, and colleagues tried heating organics and perchlorates like this on Earth, the resulting combustion left no trace of organics behind.
On the plus side, this discovery means that there may, indeed, be proof of life on Mars... it just makes us look rather embarrassed for having wasted years of possible exploration by accidentally looking in the wrong way for it.
Mars robots may have destroyed evidence of life [New Scientist]