New analysis of an experiment performed by the Viking landers suggests that evidence of microbial life in the Martian soil may have been detected 36 years ago. As one of the authors of this new paper puts it: “on the basis of what we’ve done so far, I’d say I’m 99 percent sure there’s life there.” Whoa.
The experiment that the researchers looked at has been a controversial one for a very long time. It was called the Labeled Release (LR) experiment, and it was one of a set of four different tests that the Viking landers carried to try to detect life on Mars. In the LR experiment, the lander scooped up a sample of Martian soil and dumped it into a chamber which was then sealed up. A drop of a slightly radioactive nutrient solution was added, and then the air above the soil sample was monitored so see if there was anything alive in the soil metabolizing those nutrients.
To the surprise of everyone, the LR experiment detected a steady stream of radioactivity coming out of the soil after the nutrient solution was added. Something was definitely going on. However, the other three experiments didn’t come up with anything at all, and the consensus back in 1976 was that the LR result was just some chemical reaction caused by rocks as opposed to any sign of microbial life.
New research published last month in the International Journal of Aeronautical and Space Sciences has taken a fresh look at the Viking LR experiment results, and the authors of this paper seem confident that the best way to explain the data is through the existence of microbial life after all.