High Survivability of Micrometeorites on Mars: Sites With Enhanced Availability of Limiting Nutrients

Abstract

NASA's strategy in exploring Mars has been to follow the water, because water is essential for life, and it has been found that there are many locations where there was once liquid water on the surface. Now perhaps, to narrow down the search for life on a barren basalt‐dominated surface, there needs to be a refocusing to a strategy of “follow the nutrients.” Here we model the entry of metallic micrometeoroids through the Martian atmosphere, and investigate variations in micrometeorite abundance at an analogue site on the Nullarbor Plain in Australia, to determine where the common limiting nutrients available in these (e.g., P, S, Fe) become concentrated on the surface of Mars. We find that dense micrometeorites are abundant in a range of desert environments, becoming concentrated by aeolian processes into specific sites that would be easily investigated by a robotic rover. Our modeling suggests that micrometeorites are currently far more abundant on the surface of Mars than on Earth, and given the far greater abundance of water and warmer conditions on Earth and thus much more active weather system, this was likely true throughout the history of Mars. Because micrometeorites contain a variety of redox sensitive minerals including FeNi alloys, sulfide and phosphide minerals, and organic compounds, the sites where these become concentrated are far more nutrient rich, and thus more compatible with chemolithotrophic life than most of the Martian surface.

Micrometeorites: Insights into the flux, sources and atmospheric entry of extraterrestrial dust at Earth

“…Antarctic moraines are also undoubtedly wind traps for dense particles (Genge et al, 2018). Bare rock crevasses also have the potential to trap wind transported grains (Tomkins et al, 2019).…”

“…Bi et al, 1993). In some localities in which micrometeorites are found, such as within fluvial deposits (Bi et al, 1993) or within sand dunes (Fioretti et al, 1998), the accumulation of particles is entirely the result of sedimentary concentration and thus abundances of MMs might be several orders of magnitude larger than the background flux (Tomkins et al, 2019). Roof top gutters can also be included in this category since they are essentially hydrodynamic traps and concentrate large dense particles at the expense of low density particles (Genge et al, 2017a).…”

“…2). Winnowing can also be expected to occur in crevasses in rock traps owing to the Bernouli effect during windstorms (Tomkins et al, 2019).…”

A small S-MIF signal in Martian regolith pyrite: Implications for the atmosphere

“…Wittman et al, 2015). Because the Martian surface has been accumulating meteorite and micrometeorite debris for billions of years (Tomkins et al, 2019), another indicator of surface contamination might be unusually elevated HSE abundances. The regolith breccia meteorites are HSE enriched (Goderis et al, 2016), and the surfacecontaminated Miller Range nakhlite samples are subtly HSE enriched (Mari et al, 2019), whereas neither Los Angeles nor NWA 2990 (and pairs) are HSE enriched (Yang et al, 2015), again suggesting minimal surface contamination.…”

Atmospheric entry of sub-millimetre-sized grains into Mars atmosphere: white soft mineral micrometeoroids

“…The total mass of material reaching the planet's surface depends on the fraction of micrometeorites that survive atmospheric entry. Interesting models of micrometeoroids entering Mars atmosphere have been recently developed (Tomkins et al ., 2019; Wilson et al ., 2019): their results suggest that a higher rate of micrograins survive the falling on Mars, therefore they should be more abundant on its surface. Moreover, these particles might provide an important source of nutrients for the emergence of life, since they have temperatures below the maximum hydrocarbon sublimation temperature on Mars.…”