Geology of the InSight landing site on Mars

Abstract

spacecraft landed successfully on Mars and imaged the surface to characterize the surficial geology. Here we report on the geology and subsurface structure of the landing site to aid in situ geophysical investigations. InSight landed in a degraded impact crater in Elysium Planitia on a smooth sandy, granule-and pebble-rich surface with few rocks. Superposed impact craters are common and eolian bedforms are sparse. During landing, pulsed retrorockets modified the surface to reveal a near surface stratigraphy of surficial dust, over thin unconsolidated sand, underlain by a variable thickness duricrust, with poorly sorted, unconsolidated sand with rocks beneath. Impact, eolian, and mass wasting processes have dominantly modified the surface. Surface observations are consistent with expectations made from remote sensing data prior to landing indicating a surface composed of an impactfragmented regolith overlying basaltic lava flows.

Calibration of the HP3 Radiometer on InSight

“…The cause of this increase is unknown but the sensitivity of both sensors now have a similar value that is consistent with expectations for that design. The temperatures observed using the recalibrated sensitivity are consistent with expectations for the observed surface (Golombek et al, ).…”

“…The intended use of these sensors was to provide some spectrally resolved information in case that there is a large surface inhomogeneity in the FOV, for example, from larger boulders or pockets of aeolian dust. The InSight landing site is fairly homogeneous and flat, without any clasts larger than 10 cm within the FOVs of RAD (Golombek et al, ), so that such information is less useful. The narrowband sensors, however, might still be useful in investigating the temperature response to the lander shadow moving throughout the spot observed by FOV 1.…”

“…Differences could be related to local differences of albedo and other thermophysical properties from those used in the model, and the effect of the InSight lander itself. Golombek et al () report that the thermal inertia indicated by the FOV 2 broadband sensor data is in the range of 160 to 230 Jm −2 K −1 s −1/2 . The dust cover near the lander has been disturbed by the landing rockets, reducing the albedo by approximately 35% (Golombek et al, ).…”

“…Golombek et al () report that the thermal inertia indicated by the FOV 2 broadband sensor data is in the range of 160 to 230 Jm −2 K −1 s −1/2 . The dust cover near the lander has been disturbed by the landing rockets, reducing the albedo by approximately 35% (Golombek et al, ). The spot observed by RAD FOV 1 in approximately 0.5‐m distance from the lander deck (see Figure 11 in Spohn et al, ) is affected by solar panel shadows passing through in the morning and afternoon Figure shows the periods of shadowing based on the nominal lander orientation and distance to the surface, which are approximately the same as the actual values.…”

“…In case the full depth cannot be reached or if measurements cannot take place over a full Mars year, the HP 3 instrument also includes a radiometer (Kopp et al, ), abbreviated to RAD, to observe the surface brightness temperature and thus the external forcing directly. In situ radiometers can also be used to derive thermophysical properties of the observed ground, such as thermal inertia (e.g., Fergason et al, ; Golombek et al, ; Grott et al, ; Vasavada et al, ). The InSight lander also has a comprehensive suite of meteorological sensors, which enable atmospheric science that is enhanced by the RAD data (Banfield et al, ; Spiga et al, ).…”