Dust devil tracks

Many areas on Mars experience the passage of giant dust devils. These dust devils leave tracks on the surface of Mars because they disturb a thin coating of fine bright dust that covers most of the Martian surface. When a dust devil goes by it blows away the coating and exposes the underlying dark surface. Within a few weeks, the dark track assumes its former bright colour, either by being re-covered through wind action or due to surface oxidation through exposure to sunlight and the Martian atmosphere.

Main article: Martian soil § Atmospheric dust
Martian dust devil – in Amazonis Planitia (10 April 2001) (also) (video (02:19)).

Formation and dynamics

Dust devils occur when the sun warms up the air near a flat, dry surface. The warm air then rises quickly through the cooler air and begins spinning while moving ahead. This spinning, moving cell may pick up dust and sand and leave behind a clean surface.[1]

Observation

Dust devils on Mars have been photographed both from the ground and high overhead from orbit. They have even blown dust off the solar panels of two Rovers on Mars, thereby greatly extending their useful lifetime.[2] The pattern of the tracks has been shown to change every few months.[3] A study that combined data from the High Resolution Stereo Camera (HRSC) and the Mars Orbiter Camera (MOC) found that some large dust devils on Mars have a diameter of 700 metres (2,300 ft) and last at least 26 minutes.[4] Measurements from the Curiosity Rover confirms that the pressure drops when a dust devil passes nearby.[5]

Changes through time

A dust devil that was previously imaged in 2009, there was information found about two years later showing the tracks visible from the previous imaging are completely different from the old ones meaning there had been a dust storm to erase the old tracks.[6]

  • Mars without a dust storm on June 2001 (on left) and with a global dust storm on July 2001 (on right), as seen by Mars Global Surveyor

Since it is not always too easy to observe these dust devil tracks on Mars tests have been done on Earth to further our understanding of these storms. Traditionally dust devils leave tracks that are darker, but satellite images have captured some cases where they are lighter than the traditional markings. In conclusion the marks were not darker than usual but the sand had been darkened by five minutes of rainfall during the previous night. Since there is no proof of water on Mars indefinitely it is believed that these lighter marks are being held together by electrostatic forces.[7]

Images
Dust devil on Mars - viewed by the Curiosity rover - (August 9, 2020)
Dust devil on Mars (MGS).
Dust devils cause twisting dark trails on the Martian surface.
Serpent dust devil of Mars (MRO).
Dust devils in Valles Marineris (MRO).

References
  1. HiRISE | (PSP_00481_2410). Hirise.lpl.arizona.edu. Retrieved on 7 August 2011.
  2. Mars Exploration Rover Mission: Press Release Images: Spirit. Marsrovers.jpl.nasa.gov. Retrieved on 7 August 2011.
  3. http://hirise.lpl.arizona.edu/PSP_005383_1255
  4. Reiss, D. et al. 2011. Multitemporal observations of identical active dust devils on Mars with High Resolution Stereo Camera (HRSC) and Mars Orbiter Camera (MOC). Icarus. 215:358–369.
  5. Kahanpaa, H., et al. 2018. MARTIAN DUST DEVILS OBSERVED SIMULTANEOUSLY BY IMAGING AND BY METEOROLOGICAL MEASUREMENTS. 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083). 1442.pdf
  6. "Dust Devil Tracks". HiRISE.com. 15 May 2013. Retrieved 30 November 2016.
  7. Icarus, Dennis (24 September 2010). "Mars Dust-Devil Mystery Solved on Earth". www.wired.com. Wired. Retrieved 30 November 2016.

See also
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