Locations of all the ACS detection attempts close to Gale crater with their corresponding information given in the table on the right. Red circles correspond to the location where the upper limit was inferred, while the red line extending from it corresponds to the track of the LOS tangent point projected on the surface while its altitude was drifting in the 0 to 50 km altitude range. The displayed spectrum corresponds to the closest approach that revealed a CH₄ upper limit of ~100 pptv and that is compared to a synthetic CH₄ signature of 100 and 500 pptv.