MODELED SEISMIC EFFECTS OF RECENT METEOROID IMPACTS ON MARS: PREDICTIONS FOR THE INSIGHT LANDER

The detailed structure of the Martian interior places essential constraints on the formation, evolution, and dynamics of Mars. Impact events are key sources of seismic waves for interrogating internal structure that will be detected by the future NASA Discovery Program lander InSight. InSight is instrumented to monitor thermal, seismic, and other geophysical parameters within Mars. Recent, fresh craters formed by ongoing impacts are detectable in high-resolution orbital images of the Martian surface providing an extremely accurate epicenter for seismic recordings of the impact, and enabling calibration of Martian seismic velocities and retrieval of internal structure. Thus detecting and subsequently imaging recent impacts will be an invaluable source of information for constraining the interior as well as the current cratering rate on Mars.

We use a detailed characterization of crater morphometry and spatial information for new, dated impacts to investigate recent impact-produced seismic activity on Mars. New imaging with the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter conducted for the mission landing site selection process has revealed multiple impacts features that were not visible in images collected prior to 2008. For example, a new 5.81 m diameter crater (4.290° N; 135.260° E) that is surrounded by a ~150 m blast zone with significant dust removal was identified using HiRISE images. This impact feature is located within two of the landing ellipses being considered for InSight .

For a range of target properties (bedrock vs. regolith), we calculate that this recent impact would have produced a seismic event with a magnitude between 0.5 to 2.1 M_w, a moment release well within the detectability of the nearby InSight SEIS instrument. The resulting seismic amplitudes for this and similar impacts allow us to quantify the detectable distances for body and surface wave phases and also to implement techniques to recover Martian internal structure from a single 3-component seismometer.