John Edgar
Gather.town id
FMM06
Poster Title
Following the wind on Mars
Institution
Newcastle University
Abstract (short summary)
In the current cold and arid Martian epoch, wind driven processes have likely been the dominant mode of erosion and landscape modification. Sand fluxes comparable to Earth’s have been observed on Mars through the migration of ripples and dunes across the surface [1, 2]. The driving force behind the movement of such features is the impact of saltating sand sized particles. These impacts result in the abrasion of silicate minerals and the generation of dust [3].
Here we report preliminary results from experiments designed to test the dependence of mineral abrasion on temperature. We simulated the saltation of sand sized (125 – 300 µm) olivine, pyroxene, feldspar, opal and quartz, at temperatures between 193 K and 293 K – typical of the surface of Mars. Our 75 day experiment was equivalent to ~ 6 years of continuous sand mobilisation at close to threshold wind speeds (~ 1 ms-1). This resulted in the comminution of between 4.0 ± 0.4 and 13.6 ± 0.8 % by mass of each sample to below 125 µm. Importantly, each of the minerals tested produced significantly (p .05) less fines at 193 K than at 293 K, with a mean decrease of ~ 22 %.
These results suggest that the contribution of dust generated from saltation on Mars is temperature dependant, potentially linking dust generation to obliquity and other Martian temperature controls such as atmospheric composition and solar luminosity. There may also be implications for Martian drilling campaigns; the increase in resistance to the abrasion of minerals at low temperatures highlighted in this study could lead to slower than expected rates of penetration on Mars.
[1] Bridges, N. T. et al. (2012), Nature 485, 339. [2] Silvestro, S. et al. (2020), JOGR: Planets 125(8) e2020JE006446. [3] Merrison, J., (2012), Aeolian Research 4, 1-16.
Here we report preliminary results from experiments designed to test the dependence of mineral abrasion on temperature. We simulated the saltation of sand sized (125 – 300 µm) olivine, pyroxene, feldspar, opal and quartz, at temperatures between 193 K and 293 K – typical of the surface of Mars. Our 75 day experiment was equivalent to ~ 6 years of continuous sand mobilisation at close to threshold wind speeds (~ 1 ms-1). This resulted in the comminution of between 4.0 ± 0.4 and 13.6 ± 0.8 % by mass of each sample to below 125 µm. Importantly, each of the minerals tested produced significantly (p .05) less fines at 193 K than at 293 K, with a mean decrease of ~ 22 %.
These results suggest that the contribution of dust generated from saltation on Mars is temperature dependant, potentially linking dust generation to obliquity and other Martian temperature controls such as atmospheric composition and solar luminosity. There may also be implications for Martian drilling campaigns; the increase in resistance to the abrasion of minerals at low temperatures highlighted in this study could lead to slower than expected rates of penetration on Mars.
[1] Bridges, N. T. et al. (2012), Nature 485, 339. [2] Silvestro, S. et al. (2020), JOGR: Planets 125(8) e2020JE006446. [3] Merrison, J., (2012), Aeolian Research 4, 1-16.
Plain text (extended) Summary
Slide 1 gives an introduction explaining that Mars is a cold planet, where the wind is the dominant form of erosion. The question is posed: How do different Martian surface materials respond to the erosive forces and how does the temperature affect this? This is important to know because the dust that is generated from this erosion can form oxidants with atmospheric species and these can destroy organic material as well as harm humans. The temperature dependence could also be important if you are trying to drill on Mars at lower temperatures. In the lower right corner there is an image of a sand dune on Mars with 2 types of ripples on it.
Slide 2 shows how cold Mars is over each day for a year using data from NASA’s curiosity rover, a graph shows that the temperatures range from roughly 180 K to 280 K on a given day. It then explains briefly that Mars is basaltic which means its surface contains minerals such as feldspar, olivine and pyroxene. There are also minor amounts of 2 iron minerals magnetite and hematite as well as the silicates quartz and opal. There is an image on the right hand side showing 10 m ripples close to the South Polar Layered Region.
Slide 3 explains how the team simulated the saltation of sand in the lab by putting different minerals in ampoules and attaching them to discs that were then rotated. Each of these set ups can be placed in incubators to regulate the temperature. Each rotation causes the sand to fall from one end of the ampoule to the other causing impacts that replicate the impacts of saltating sand on Mars. There are then two plots of percentage weight abraded vs the temperature at which the minerals were abraded. The first plot shows that all of the minerals they tested were more resistant to abrasion at lower temperatures. The second plot shows that some minerals change resistance to abrasion with temperature at different rates than others.
Slide 2 shows how cold Mars is over each day for a year using data from NASA’s curiosity rover, a graph shows that the temperatures range from roughly 180 K to 280 K on a given day. It then explains briefly that Mars is basaltic which means its surface contains minerals such as feldspar, olivine and pyroxene. There are also minor amounts of 2 iron minerals magnetite and hematite as well as the silicates quartz and opal. There is an image on the right hand side showing 10 m ripples close to the South Polar Layered Region.
Slide 3 explains how the team simulated the saltation of sand in the lab by putting different minerals in ampoules and attaching them to discs that were then rotated. Each of these set ups can be placed in incubators to regulate the temperature. Each rotation causes the sand to fall from one end of the ampoule to the other causing impacts that replicate the impacts of saltating sand on Mars. There are then two plots of percentage weight abraded vs the temperature at which the minerals were abraded. The first plot shows that all of the minerals they tested were more resistant to abrasion at lower temperatures. The second plot shows that some minerals change resistance to abrasion with temperature at different rates than others.
URL
j.o.edgar2@newcastle.ac.uk
Poster file