Dunes, dust devils and the Martian weather

October 8, 2015 by Lori Fenton, SETI Institute
Dunes, dust devils and the Martian weather

I study how windblown desert features can be used to monitor wind patterns and atmospheric conditions in remote places, such as Mars, where there are plenty of pictures of the surface but not many instruments on the ground.

These features include and ripples, , and surfaces scoured by sandblasting. I use , remote sensing, and field work at planetary analog sites to figure out how these desert features can be used to learn about, and monitor, changing weather patterns.

Dunes and ripples are windblown piles of sand that align in particular ways, depending on whether a region experiences winds blowing from one, two, or more directions throughout the year. By careful study of the alignment of the dunes and ripples, we can figure out which directions the wind blows, and which winds are the strongest. Wind regimes change as the climate shifts, forcing dunes to reorient – but they take time to do so, so that older can often be seen beneath the new ones, like old ink on a palimpsest. By deciphering these old patterns, we can learn something about ancient wind regimes and the climates that produced them.

Dust devils form in deserts where the surface is much hotter than the air above it; their occurrence, size, and movement can tell us about where they form. Dust devils loft dust into the atmosphere, which absorbs sunlight and influences atmospheric temperatures. On Earth, mineral dust aerosols are a major driver of climate change, but the role they play is not well understood. On Mars, lofted dust is even more important and even less well understood. With a better understanding of devil development and physical characteristics, we can make inferences about local weather conditions in remote places where there are no weather stations.

Dunes, dust devils and the Martian weather
A Piece of Mars: The dark dunes in this 0.96×0.54 km (0.60×0.34 mi) scene are slowly migrating towards the lower left. Look closer and you’ll see brighter ripples between the dunes – the biggest ones are ~8m (26 ft) apart. They form trains in the wake of the dunes. Why? This is where the dunes previously marched on by, obliterating the ripples as they went. Ripples form again after the dunes pass by, growing in size and regularity with time. Credit: HiRISE ESP_01746_2570, NASA/JPL/Univ. of Arizona

How does this relate to astrobiology? Thriving ecosystems only form where local climatic conditions are comfortable and stable. Understanding the climate state of exoplanets requires use of climate models, which need as much input data as they can get. The better we can remotely determine the climate patterns on another world, the better we will be able to figure out if they're stable enough to allow life to form and evolve. My work is to improve those models.

Dunes, dust devils and the Martian weather
A towering dust devil casts a serpentine shadow over the Martian surface in this image acquired by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/Univ. of Arizona

Explore further: Spinning up a dust devil on Mars

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not rated yet Oct 08, 2015
Terraforming theories often focus on providing water to Mars, but Mars obviously already had plenty water and CO2.

What Mars really needs is nitrogen. I suppose that just a millibar worth of nitrogen atmosphere, introduced from mining something like Titan, would be enough to stabilize the atmosphere and transport heat from day side to night side, and from equator to pole, to sublimate the CO2 ice caps and therefore provide long-term stability. The advantage of Nitrogen is that it remains a gas even at the lowest temperatures on Mars, so it would never liquify or freeze out like the CO2 or water vapor.

It's interesting that we have one planet devoid of nitrogen, and we have a large moon teeming with nitrogen inside the same solar system. It's as if the moon was put there to be used to heal the planet Mars.

I think solar sails and ion engines may one day make it possible to move resources between these locations.

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