Remember the discovery of methane in the martian atmosphere? Now scientists can't find any evidence of it, at all

In 2003, scientists from NASA's Goddard Space Center made the first-ever detection of trace amounts of methane in Mars' atmosphere, a find which was confirmed a year later by the ESA's Mars Express orbiter. In December of 2014, the Curiosity rover detected a tenfold spike of methane at the base of the Gale Crater, and uncovered evidence that indicated that Mars has a seasonal methane cycle, where levels peak in the late northern summer.