Figure 2

Estimated methane fluxes from the aeolian abrasion of analogue Martian rock samples using a period of 30 sols and assuming vertical mixing over the entire Martian atmospheric column; a – g the methane flux was calculated from: (a) basalt with abrasion rate of 1 × 10⁻⁵ µm yr⁻¹, (b) evaporites, 1 × 10⁻⁴ µm yr⁻¹, (c) shale, 1 × 10⁻⁴ µm yr⁻¹, (d) basalt, 0.75 µm yr⁻¹, (e) evaporites, 0.75 µm yr⁻¹, (f) mudstone/shale, 0.75 µm yr⁻¹, (g) basalt, 50 µm yr⁻¹, (h) evaporites, 500 µm yr⁻¹, (i) mudstone/shale, 500 µm yr⁻¹. The purple line is the average (33 ppb) methane flux of the plume measured by ground-based observations³, the red and blue lines are the peak (700 ppb) and average (400 ppb) values of methane measured by the Curiosity rover respectively² and the dashed line represents the methane flux from organic breakdown⁵. The box that represents each sample is bound by the maximum and minimum flux from a range of measurements (see Supplementary Information), and the line situated in the box represents the median value of the fluxes from the samples.