A little dramatic perhaps, but a controversy has been rumbling on for many years about the scientific data returned by the 1976 Viking Missions to Mars. For many, the results signalled the final death knell for the long cherished hope that Mars might still harbour some primitive form of life, but not everyone agreed. Conspiracy theorists like to say there was a cover-up of the results, but far more plausible is the belief that the scientists running the probes simply got the results wrong or mis-interpreted them. One such proponent of this theory is Dr. Gilbert V. Levin, who was actually one of the mission scientists in charge of the Viking Labelled Release (LR) experiment. This was designed to detect the uptake of a radioactively tagged liquid nutrient by microbes in the soil. The idea was that gases emitted by these microbes would show the radioactive tagging. Initial results were in line with this prediction but the overall results proved inconsistent. Dr. Levin has since argued vigorously that his experiment did show signs of life, but now we have a new take on the experiment that suggests the probes actually killed any existing Martian microbes. In a paper presented to the American Astronomical Society in Seattle, geology professor Dirk Schulze-Makuch has suggested that the microbes may have been a hydrogen peroxide based life form and that in heating the soil sample during the experiment, the Viking probes would have very effectively killed their intended targets. A NASA scientist is now looking at using the forthcoming Phoenix mission to look into the theory, though it will mean some science on the fly to find a way of adapting the existing instrument package to look for hydrogen peroxide based microbes. ABC News has the detailed story.