Here, megaripples are shown at the bottom of center adjacent to the north polar sand dunes in this perspective view utilizing data returned from the High Resolution Imaging Science Experiment (HiRISE). These northern polar megaripples and dunes yield the greatest known sand fluxes on the planet, driven by summer katabatic winds modulated by the seasonal CO2 cap retreat. Polar bedform sites with active megaripples, as seen in HiRISE. We mapped megaripples and adjacent bedforms across the north polar sand seas, the most extensive collection of dune fields on Mars,” stated Chojnacki, lead author of “Widespread Megaripple Activity Across the North Polar Ergs of Mars” that appears in Journal of Geophysical Research: Planets.
Here, megaripples are revealed at the bottom of center nearby to the north polar sand dunes in this viewpoint view utilizing data returned from the High Resolution Imaging Science Experiment (HiRISE). These northern polar megaripples and dunes yield the greatest known sand fluxes on the world, driven by summer season katabatic winds regulated by the seasonal CO2 cap retreat.
Megaripples, intermediate-scale bedforms triggered by the action of the wind, have been studied extensively and believed to be largely inactive relics of previous environments, conserve for a couple of exceptions. A new paper by Planetary Science Institute Research Scientist Matthew Chojnacki shows that abundant megaripple populations were recognized throughout the north polar area of Mars and were found to be migrating with ripples and dunes.
Megaripples on Mars have to do with 1 to 2 meters high and have 5 to 40 meter spacing, where there size falls between ripples that are about 40 centimeters high with 1 to 5 meter spacing and dunes that can reach hundreds of meters in height with spacing of 100 to 300 meters. Whereas the megaripples migration rates are slow in contrast (average of 0.13 meters per Earth year), a few of the close-by ripples were found to migrate an average equivalent of 9.6 meters each year over just 22 days in northern summer season– extraordinary rates for Mars. These high rates of sand motion assistance discuss the megaripple activity.
Polar bedform sites with active megaripples, as viewed in HiRISE. Approximate transportation instructions is towards the lower left and the inset is 100 meters large. Credit: HiRISE information are thanks to NASA/JPL/University of Arizona
” Using repeat HiRISE images acquired over long period of time– 6 Mars years or 13 Earth years– we examined the vibrant activity of polar bedforms. We discovered the thin Martian atmosphere can mobilize some grainy megaripples, overturning prior ideas that these were fixed relic landforms from a past climate. We mapped megaripples and nearby bedforms across the north polar sand seas, the most extensive collection of dune fields on Mars,” stated Chojnacki, lead author of “Widespread Megaripple Activity Across the North Polar Ergs of Mars” that appears in Journal of Geophysical Research: Planets.
” Megaripples were found to be prevalent throughout the area and moving at fairly high rates relative to other sites on Mars that are at lower latitudes. “In contrast, other megaripples appear to be stabilized, a most likely result of inter-granular ice within low wind locations.”
Reference: “Widespread Megaripple Activity Across the North Polar Ergs of Mars” by Matthew Chojnacki, David A. Vaz, Simone Silvestro and David C. A. Silva, 12 November 2021, JGR: Planets.DOI: 10.1029/ 2021JE006970.
The job was moneyed by NASA Mars Data Analysis program grant 80NSSC20K1066.
Part of the unpredictability when studying planetary polar landforms is the long, cold polar winter that ultimately covers the area in co2 and water ice. For wind-driven bedforms, such as megaripples, that suggests they are unable to move for nearly half of the year. “However, it appears the late spring and summer season winds that came down off the polar cap more than make up for these other periods of inactivity,” Chojnacki said.