Evaporating dry ice chunks create gouges on Mars
Scientists think they have solved the mystery of the gouges that appear seasonally on some hillsides on Mars: Chunks of dry ice that slide down the slope and then evaporate, leaving no trace.
During the martian winter, carbon dioxide ice freezes over parts of the planet’s surface and sublimates back into a gas during the spring thaw. But according to the model presented here today at a meeting of the American Geophysical Union, chunks of warming dry ice may also break off from the crests of dunes and skid down slopes. This is no ordinary tumble—according to the model, the bases of the chunks are continually sublimating, resulting in a hovercraftlike motion that gouges the dune while propelling the ice down slopes. Solid ice that survives to the bottom settles into a pit before dissipating back into the atmosphere.
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Scientists think they have solved the mystery of the gouges that appear seasonally on some hillsides on Mars: Chunks of dry ice that slide down the slope and then evaporate, leaving no trace.
During the martian winter, carbon dioxide ice freezes over parts of the planet’s surface and sublimates back into a gas during the spring thaw. But according to the model presented here today at a meeting of the American Geophysical Union, chunks of warming dry ice may also break off from the crests of dunes and skid down slopes. This is no ordinary tumble—according to the model, the bases of the chunks are continually sublimating, resulting in a hovercraftlike motion that gouges the dune while propelling the ice down slopes. Solid ice that survives to the bottom settles into a pit before dissipating back into the atmosphere.
Readers!
My annual February birthday fund-raising drive for Behind the Black is now over. Thank you to everyone who donated or subscribed. While not a record-setter, the donations were more than sufficient and slightly above average.
As I have said many times before, I can’t express what it means to me to get such support, especially as no one is required to pay anything to read my work. Thank you all again!
For those readers who like my work here at Behind the Black and haven't contributed so far, please consider donating or subscribing. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Every one of those 2020 conclusions has turned out right.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
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P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
How does pure dry ice form on the top of those sand dunes?
As snow or as liquid?
And if liquid wouldn’t it soak into the sand and possibly solidify inside the sand?
So if it soaks in then it would be mostly sand and not carbon dioxide. Frozen mud. The CD ice would just hold the ‘dirt’ together and when it thaws or sublimates away wouldn’t it leave piles of sand and or dirt?
As snow shouldn’t it just sublimate away faster and thus not have a chance to slide down the hill?