Rate of wind abrasion on Mars

Abstract

Estimation of the rate of aeolian abrasion of rocks on Mars requires knowledge of (1) particle flux, (2) susceptibilities to abrasion of various rocks, and (3) wind frequencies on Mars. Fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the Viking meteorology experiment. Assuming an abundant supply of sand‐sized particles, estimated rates range up to 2.1×10−2 cm of abrasion per year in the vicinity of Viking Lander 1. This rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux. The discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces.We consider the primary reason to be related to the agents of abrasion. Either windblown grains are in very short supply, or the grains are ineffective as agents of abrasion. At least some sand‐sized (∼100 μm) grains appear to be present, as inferred from both lander and orbiter observations. High rates of abrasion occur for all experimental cases involving sands of quartz, basalt, or ash. However, previous studies have shown that sand is quickly comminuted to silt‐ and clay‐sized grains in the martian aeolian regime. Experiments also show that these fine grains are electrostatically charged and bond together as sand‐sized aggregates. Laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand, aggregates form a protective veneer on the target surface and can give rise to extremely low abrasion rates.

Wind-Related Processes Detected by the Spirit Rover at Gusev Crater, Mars

“…1H) is a light-toned, flat rock with ventifact grooves cut into the upper surface. We suggest that the prominent grooves resulted from the trajectories of abrading particles that struck the rock at low angles, gouging the surface, an interpretation consistent with laboratory experiments of rock abrasion under martian conditions (31,32).…”

Rock coatings and aeolian abrasion on Mars: Application to the Pathfinder landing site

“…The wind frequency at MPF could be lower than at VL1. The value of Zo for VL 1 was less than a centimeter [Sutton et al, 1978], which was deemed to have a negligible effect on [Greeley et al, 1982]. Compare this to MPF, where Zo = 2 cm and u,t increases substantially, thus requiring stronger winds averaged over the landing site area to move 100-1am sand.…”

“…Abrasion un-where q is the particle flux, fis the wind frequency, and S,, is the der current atmospheric conditions will likely result from parti-susceptibility to abrasion [Greeley et al, 1982] and R has units of cles with low saltation velocities. mass per area per unit time (e.g., g cm -2 s'•).…”

Introduction to the Planetary Dunes special issue, and the aeolian career of Ronald Greeley

“…In lieu of that, following are some key topics in planetary aeolian studies to which he made significant contributions over the years: wind tunnel and laboratory experiments (Greeley et al, 1974(Greeley et al, , 1980(Greeley et al, , 1981(Greeley et al, , 1982(Greeley et al, , 1984a(Greeley et al, ,b, 2000b(Greeley et al, , 2003aGreeley and Iversen, 1985;Lorenz et al, 2005;Neakrase et al, 2006;Neakrase and Greeley, 2010); erosion and abrasion by wind-blown sand (Greeley et al, 1982;Greeley and Iversen, 1985;Bridges et al, 1999;Golombek et al, 2006;Thomson et al, 2008); particle motion induced by the wind White et al, 1976;Greeley et al, 1976Greeley et al, , 1980Greeley et al, , 1988Greeley andIversen, 1985, 1987;Greeley, 2002;Sullivan et al, 2008); dust mobilization and dust devils (Greeley et al, 1981(Greeley et al, , 2000b(Greeley et al, , 2003a(Greeley et al, , 2004b(Greeley et al, , 2006bGreeley and Iversen, 1985;Greeley and Williams, 1994;Greeley, 2002;Neakrase et al, 2006;Stanzel et al, 2008;Neakrase and Greeley, 2010); field investigations of aeolian sites (Greeley andIversen, 1985, 1987;Lancaster et al, 1987;…”