 The results from incubating Martian soil with complex media, and from pyrolysis of soil followed by gas chromatography and mass spectrometry of the pyrolysis products, suggested that the surface of Mars is lifeless.Furthermore, in the soil samples analyzed by the Viking program there were no detectable biochemical footprints in the form of organic compounds that might be expected if living organisms ever thrived on Mars.However, in 2013, NASA’s Curiosity rover provided evidence of an ancient Martian lake (in existence about 3.7 billion years ago) that may have been capable of supporting life for long stretches --- perhaps for millions of years.