The issue focused on allegations that NASA investigators overlooked chemical contamination from spacecraft instruments aboard Mercury's famed Pathfinder spacecraft during experiments performed before NASA launched NASA's Curiosity rover in August 2012. The probe landed with scientific discoveries including signs of microbial life and traces of methane hydroxide — an odorless chemical suspected of generating greenhouse gases — among other chemicals detected by instrument measurements and laboratory analyses. NASA scientists concluded at the time that NASA scientists missed chemical contamination due to incomplete engineering controls used during laboratory experiments on Mercury spacecraft prior to landing. NASA