Context: The author, Gilbert Levin, was the Principal Investigator of the Labeled Release experiment that was sent with the Viking landers. The experiment is be

Context: The author, Gilbert Levin, was the Principal Investigator of the Labeled Release experiment that was sent with the Viking landers. The experiment is beautiful in its thoroughness and elegance, > In the LR experiment, a sample of Martian soil was inoculated with a drop of very dilute aqueous nutrient solution. The nutrients (7 molecules that were Miller-Urey products) were tagged with radioactive 14C. The air above the soil was monitored for the evolution of radioactive 14CO2 (or other carbon-based[13]) gas as evidence that microorganisms in the soil had metabolized one or more of the nutrients. > The result was quite a surprise, considering the negative results of the first two tests, with a steady stream of radioactive gases being given off by the soil immediately following the first injection. The experiment was done by both Viking probes, the first using a sample from the surface exposed to sunlight and the second probe taking the sample from underneath a rock; both initial injections came back positive.[1] > Sterilization control tests were subsequently carried out by heating various soil samples. Samples heated for 3 hours at 160 °C gave off no radioactive gas when nutrients were injected, and samples heated for 3 hours at 50 °C exhibited a substantial reduction in radioactive gas released following nutrient injection.[14] A sample stored at 10 °C for several months was later tested showing significantly reduced radioactive gas release. There's debate whether it's simple oxidation due to superoxidizers present in the soil due to the high UV environment of Mars, or if the positive detection really was life. Levin and the other scientists on the team have contended that it's likely to be evidence for life. Others have disagreed. Either way, it's a great experiment to re-run with our better technology. This time we could add steps to eliminate the chemical reaction hypothesis more thoroughly. Even if it's a negative, it's still an important result. It is my personal hope that the samples that we'll obtain via Mars Sample Return will go towards ending this debate.