Black and white photo of particles and a bar graph.
(a) View of the particles that fell from Dump #3 (picture width: 1.53 meters) and b) frequency of grain size in plume generated by Dump #3, given a wind speed of 5.3 meters/second. The color of boxes in (a) corresponds to the grain size shown in (b). Credit: Verdier et al. [2023], Figure 21
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Planets

Imagine letting a handful of sand flow through your fingers on a windy day. The biggest grains fall straight to the ground, but the smaller ones get carried away. By simulating how wind entrains and sorts the grains, you could deduce the distribution of grain sizes in your fistful of sand.

Verdier et al. [2023] did exactly that, but on Mars. They took advantage of an opportunistic observation made while the InSight Lander scooped Martian soil and poured it over the tether connecting the lander to the seismometer it carried. The purpose of the maneuver was to bury the tether and improve the quality of seismic signals. As it monitored the procedure, the InSight team observed that some grains were carried up to 2 meters downwind even as they fell from the scoop 50 centimeters above the ground. The authors determined that grains larger than 500 microns fell close to the pile of dump soils and that the wind entrained particles as small as 100 microns. Even smaller dust particles were simply blown away.

This innovative measurement of the grain size distribution in Martian soil supports hypotheses that fine sand is mobilized by low-velocity winds on Mars and is involved in forming the active dunes that other rovers documented.

Citation: Verdier, N., Ansan, V., Delage, P., Ali, K. S., Beucler, E., Charalambous, C., et al. (2023). Using wind dispersion effects during the InSight tether burial activities to better constrain the regolith grain size distribution. Journal of Geophysical Research: Planets, 128, e2022JE007707.

— Laurent G. J. Montesi, Editor in Chief, JGR: Planets; and Germán Martínez, Associate Editor, JGR: Planets

Text © 2023. The authors. CC BY-NC-ND 3.0
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