A mystery surrounding the 1976 Viking mission to Mars has lingered for a quarter-century, but a recent experiment may have revealed the solution. The new results may guide future Mars missions, particularly those in search of life.
The Viking mission appeared to find that Martian soil can destroy organic molecules. Twenty-five years of trying to identify chemicals that might cause this breakdown hadn’t found a convincing explanation, says Albert S. Yen of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. So, he and his colleagues simulated the Martian surface in their laboratory. They theorized that a chemical agent, superoxide radical ions, could arise and destroy organics on Mars.