Washington: Experiments prompted by a 2008 surprise from NASA’s Phoenix Mars Lander suggest that soil examined by NASA’s Viking Mars landers in 1976 may have contained carbon-based chemical building blocks of life.
“This doesn’t say anything about the question of whether or not life has existed on Mars, but it could make a big difference in how we look for evidence to answer that question,” said Chris McKay of NASA.
Scientists had found two organic chemicals - chloromethane and dichloromethane - when the Viking landers heated samples of Martian soil.
Those are exactly what the new study found when a little perchlorate -- the surprise finding from Phoenix - was added to desert soil from Chile containing organics and analyzed in the manner of the Viking tests.
“Our results suggest that not only organics, but also perchlorate, may have been present in the soil at both Viking landing sites,” said Rafael Navarro-Gonzalez of the National Autonomous University of Mexico, Mexico City.
Even if Mars has never had life, scientists before Viking anticipated that Martian soil would contain organics from meteorites.
“For 30 years we were looking at a jigsaw puzzle with a piece missing. Phoenix has provided the missing piece: perchlorate. The perchlorate discovery by Phoenix was one of the most important results from Mars since Viking,” McKay said.
If organic compounds can indeed persist in the surface soil of Mars, contrary to the predominant thinking for three decades, one way to search for evidence of life on Mars could be to check for types of large, complex organic molecules, such as DNA, that are indicators of biological activity.
“If organics cannot persist at the surface, that approach would not be wise, but if they can, it’s a different story,” McKay said.