Two landmark discoveries reveal organic carbon on the red planet, shaping the future hunt for life on Mars.
Curiosity’s latest data reveal that the watery lake that once filled Mars’s Gale Crater catained complex organic molecules about 3.5 billion years ago. Hints of them are still preserved in sulfur-spiked rocks derived from lake sediments. Sulfur may have helped protect the organics even when the rocks were exposed at the surface to radiation and bleach-like substances called perchlorates.
By themselves, the new results aren’t evidence for ancient life on Mars; non-living processes could have yielded identical molecules. At a minimum, the study shows how traces of bygone martians could have survived for eons—if they existed at all—and it hints at where future rovers might look for them.