Mars Methane Sources in Northwestern Gale Crater Inferred from
Back-Trajectory Modeling
Abstract
During its five years of operation as of 2017, the Sample Analysis at
Mars (SAM) Tunable Laser Spectrometer (TLS) on board the Curiosity rover
has detected six methane spikes above a low background abundance in Gale
crater. The methane spikes are likely sourced by nearby emission from
the surface. Here we use inverse Lagrangian modeling techniques to
identify upstream emission regions on the Martian surface for these
methane spikes at unprecedented spatial resolutions. Inside Gale crater,
the northwestern crater floor casts the strongest influence on the
detections. Outside Gale crater, the upstream regions extend towards the
north. The contrasting results from two consecutive TLS methane
measurements point to an active emission site to the west and the
southwest of the Curiosity rover on the northwestern crater floor. The
observed spike magnitude and frequency also favor emission sites on the
northwestern crater floor, unless there are fast methane removal
mechanisms at work, or either the TLS methane spikes or the Trace Gas
Orbiter (TGO) non-detections can not be trusted.