Nearly half a century after NASA’s Viking landers touched Mars, one question shadows their experiments: Did they miss life, or did they destroy it while trying to prove it was there? Dirk Schulze-Makuch, an astrobiologist at Technical University Berlin, has proposed that Viking’s life-detection tests may have exposed native Martian microbes to lethal amounts of liquid water. Organisms adapted to an extremely dry world, he argues, might not have survived the treatment intended to reveal their metabolism. “NASA may have unwittingly uncovered life on Mars nearly 50 years ago and accidentally destroyed it before understanding its significance,” Schulze-Makuch argues. The idea challenges the assumptions behind the 1976 mission. Viking 1 and Viking 2 carried four experiments designed to search Martian soil for organic compounds, metabolic activity and changes associated with living organisms. Viking, Gas Chromatograph Mass Spectrometer. (CREDIT: National Air and Space Museum) Four tests produced an uneven picture The Gas Chromatograph Mass Spectrometer heated soil samples, separated the released compounds and identified molecules by their mass signatures. It found no organic molecules, a result …