NASA's Curiosity rover has identified a diverse set of organic molecules on Mars , including a nitrogen-bearing compound similar in structure to DNA precursors. The finding strengthens the case that ancient organic material can survive in the Martian subsurface, though it does not prove past life because the compounds could also come from geology or meteorites. Phys.org reports: The study was led by Amy Williams, Ph.D., a professor of geological sciences at the University of Florida and a scientist on the Curiosity and Perseverance Mars rover missions. Curiosity landed on Mars in 2012 to find evidence that ancient Mars had conditions that could support microbial life billions of years ago; the Perseverance rover, which landed in 2021, was sent to look for signs of any ancient life that might have formed. Among the 20-plus chemicals identified by the experiment, Curiosity spotted a nitrogen-bearing molecule with a structure similar to DNA precursors -- a chemical never before spotted on Mars.…