Details

Autor(en) / Beteiligte

• Charalambous, C.
• McClean, J. B.
• Baker, M.
• Pike, W. T.
• Golombek, M.
• Lemmon, M.
• Ansan, V.
• Perrin, C.
• Spiga, A.
• Lorenz, R. D.
• Banks, M. E.
• Murdoch, N.
• Rodriguez, S.
• Weitz, C. M.
• Grant, J. A.
• Warner, N. H.
• Garvin, J.
• Daubar, I. J.
• Hauber, E.
• Stott, A. E.
• Johnson, C. L.
• Mittelholz, A.
• Warren, T.
• Navarro, S.
• Sotomayor, L. M.
• Maki, J.
• Lucas, A.
• Banfield, D.
• Newman, C.
• Viúdez‐Moreiras, D.
• Pla‐García, J.
• Lognonné, P.
• Banerdt, W. B.

Titel

Vortex‐Dominated Aeolian Activity at InSight's Landing Site, Part 1: Multi‐Instrument Observations, Analysis, and Implications

Ist Teil von

• Journal of geophysical research. Planets, 2021-06, Vol.126 (6), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2021

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• We report the aeolian changes observed in situ by NASA's InSight lander during the first 400 sols of operations: Granule creep, saltation, dust removal, and the formation of dark surface tracks. Aeolian changes are infrequent and sporadic. However, on sols, when they do occur, they consistently appear between noon to 3 p.m., and are associated with the passage of convective vortices during periods of high vortex activity. Aeolian changes are more frequent at elevated locations, such as the top surfaces of rocks and lander footpads. InSight observed these changes using, for the first time, simultaneous in‐situ and orbital imaging and high‐frequency meteorological, seismological, and magnetic measurements. Seismometer measurements of ground acceleration constrain the timing and trajectory of convective vortex encounters, linking surface changes to source vortices. Magnetometer measurements show perturbations in magnetic field strength during the passage of convective vortices consistent with charged‐particle motion. Detachment of sand‐scale particles occurs when high background winds and vortex‐induced turbulence provide a peak surface friction wind speed above the classic saltation fluid threshold. However, detachment of dust‐ and granule‐scale particles also occurred when the surface friction wind speed remained below this threshold. This may be explained by local enhancement of the surface roughness and other effects described here and further studied in Part 2 (Baker et al., 2021). The lack of saltation and bright dust‐coated surfaces at the InSight landing site implies surface stability and the onset of particle motion may be suppressed by dust “cushioning.” This differentiates the InSight landing site from other areas on Mars that exhibit more aeolian activity. Plain Language Summary Aeolian activity, the movement of dust and sand by the wind, is common on Earth and has been observed on other planets, including Mars. A new Mars lander, InSight, has for the first time monitored aeolian changes by combining imaging with weather, seismic and magnetic field measurements. Sand grains are seen moving along the ground and dust is lifted from both artificial and natural surfaces. We found these changes were rare, but almost always happened in the early afternoon when tornado‐like phenomena, called convective vortices, passed by the lander, sometimes leaving dark surface trails behind. The combination of the background wind speed and the rotational wind speed within a vortex was likely to be high enough to detach particles from the surface and set them into motion. When these vortices passed by the lander, the seismometer detected the ground tilting, and there was a pulse in the magnetic field, indicating charged particles were part of these dust‐clearing events. Key Points Aeolian activity at InSight is observed using imaging, meteorological, seismological, and magnetic field measurements for the first time on Mars Infrequent episodes of creep, dust removal, saltation, and track formation coincide with passage of convective vortices in early afternoon Paucity of observations of saltation coupled with the bright appearance of dust‐coated surfaces suggests surface stability around InSight