London, May 25 (ANI): NASA's robot explorers may have been destroying the signs of life on Mars, say researchers.
When the twin Viking landers, sent on the planet in 1976, failed to detect even minute quantities of organic compounds, scientists were puzzled because even if Mars has never had life, comets and asteroids that have struck the planet should have scattered at least some organic molecules - though not produced by life - over its surface.
Many scientists have suggested that organics were cleansed from the surface by naturally occurring, highly reactive chemicals such as hydrogen peroxide.
Even last year, NASA's Phoenix lander, also failed to detect organics on Mars, but it did stumble on something in the Martian soil that could have been hiding the organics-a class of chemicals called perchlorates.
Perchlorates, are relatively harmless at low temperatures, but when heated to hundreds of degrees Celsius they release a lot of oxygen, which tends to cause any nearby combustible material to burn.
Both the Phoenix and Viking landers searched for organic molecules by heating soil samples to similarly high temperatures to evaporate them and analyse them in gas form.
Douglas Ming of NASA's Johnson Space Center in Houston, Texas, and colleagues tried heating organics and perchlorates like this on Earth, he found that the resulting combustion left no trace of organics behind.
Chris McKay of Ames said that iron oxides have also been suspected of interfering with the detection of organics, but perchlorates are probably far more effective.
He added that even if organics make up a few parts per thousand of the soil, Viking or Phoenix could have missed them, thus it is too soon to conclude that these materials are not there.
"We haven't looked the right way," he said.
Organic chemicals are not the only substance that mars robots may have missed on the Red Planet, they could have even missed out on carbonate salts littering the surface.
The researchers presented their results at the recent Lunar and Planetary Science Conference in Houston. (ANI)