Credit & Copyright: HiRISE,
MRO,
LPL (U. Arizona),
NASA;
Processing:
Wåodek Gåaåewski;
Text: Alex R. Howe (NASA/USRA, Reader's History of SciFi Podcast)
Explanation:
Why are these sand dunes on
Mars striped?
No one is sure.
The featured image shows striped dunes in
Kunowsky Crater on Mars, photographed recently with the
Mars Reconnaissance OrbiterÁs HiRISE Camera.
Many Martian dunes are known to be covered unevenly with carbon dioxide
(dry ice) frost,
creating patterns of light and dark areas.
Carbon dioxide doesnÁt melt, but
sublimates, turning directly into a gas.
Carbon dioxide is also a
greenhouse material even
as a solid,
so it can trap heat under the ice and
sublimate from the bottom up, causing
geyser-like eruptions.
During Martian spring, these eruptions can cause a pattern of dark
defrosting spots, where the
darker sand is exposed.
The featured image, though, was taken during Martian autumn,
when the weather is getting colder Á making these stripes particularly puzzling.
One hypothesis is that they are caused by cracks in the ice that form from weaker
eruptions or
thermal stress as part
of the day-night cycle, but research continues.
Watching these dunes and others through more
Martian seasons
may give us more clues to solve this mystery.
Text: Alex R. Howe (NASA/USRA, Reader's History of SciFi Podcast)
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Based on Astronomy Picture
Of the Day
Publications with keywords: Mars
Publications with words: Mars
See also:
- APOD: 2024 December 3 Á Ice Clouds over a Red Planet
- APOD: 2024 November 10 Á Valles Marineris: The Grand Canyon of Mars
- APOD: 2024 September 9 Á Mars: Moon, Craters, and Volcanos
- APOD: 2024 June 5 Á Shadow of a Martian Robot
- Ares 3 Landing Site: The Martian Revisited
- The Shadow of Ingenuity s Damaged Rotor Blade
- APOD: 2023 November 7 Á A Martian Dust Devil Spins By