I was still at school when the NASA’s Viking Landers sent back their first spectacular images of the bleak Martian landscape in the 1970s. I recall that something else that seemed pretty bleak at the time was the disappointing news from the analysis of the soil chemistry that - to all intents and purposes - showed no evidence of microbial life.
Traces of percholrate, an oxidizing salt, were discovered, but were dismissed as contamination from cleaning agents used on the spacecraft. So some 32 years later, when the more sophisticated wet chemistry lab on board the Phoenix Mars Lander showed the self-same percholate, some geophysicists decided to take another look at the tantalizing data from Viking.
Rafael Navarro-González and a geophysical team from the National Autonomous University of Mexico (Unam), asked if the percholate was actually a naturally occurring oxidative agent in the Martian soil. If so, could this mean that carbon-rich organic molecules could still be present on Mars after all?
To find out, the team traveled to a remote spot called Yungay in the arid heart of Chile’s Atacama desert where they knew the soil would most resemble conditions on Mars. In the experiment the researchers mixed the soil they collected with perchlorate and heated it to produce carbon dioxide as well as traces of chloromethane and dichloromethane. These same gases were also detected in the chemical reactions after the Viking Landers heated the Martian soil, suggesting that not only percholate, but also organics, may have been present.
The view from Viking. (NASA)
The real answer, of course, remains unresolved – and could well be put to rest once and for all in 2012 when the Mars Science Lab mission’s Curiosity rover is scheduled to land on the surface. But in the meantime the data collected by the Unam team suggests that data from Viking may have indeed been misinterpreted. Certainly Peter Smith, the principal investigator for the Phoenix mission, seems optimistic that this is so, and that the next mission will see signs of life in a whole new light. Commenting at last week’s Space 2010 conference in Anaheim, Calif, just a few days after the publication of Navarro-González’s paper, Smith says “I predict we will fully-measure organics on Mars at the 10 ppm (parts per million) level.”
Tell-tale ice and maybe more exposed by Phoenix? NASA/JPL and Univesity of Arizona
At the same time, he cautions that all the real answers – and probably those we have yet to ask – will not be fully answered until people arrive on Mars to explore in person. That, he says, will represent ‘the capstone’ of human exploratory endeavors in the 21st century.