Since methane was first detected in Mars' atmosphere 20 years ago, scientists have struggled to uncover its origins and how it is transported around the Red Planet. Measurements from atmospheric samples collected by NASA's Curiosity rover at Gale crater reveal fluctuations in methane levels over days and seasons, but pinpointing the timing and reasons for the variability has proved difficult. These emissions, possibly produced by subsurface microbes, could provide vital evidence of life on Mars. However, sampling strains Curiosity's limited resources, so determining both why fluctuations occur and when to best capture samples is paramount.