Skiing dry ice boulders on Mars, captured in action!
Click for full image.
Today’s cool image is an update on a previous cool image published in April 2020 about how scientists believe the grooves seen on the slope of a giant dune in Russell Crater on Mars are believed to be formed by frozen blocks of carbon dioxide sliding down the slope when spring arrives. The photo to the right, taken on March 3, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and rotated and cropped to post here, shows these grooves. As I wrote then,
Because the block is sublimating away, the gas acts as a lubricant so that it can slide down the hill. If large enough, the dry ice block will stop at the base of the hill to disappear in a small pit. If small enough, it actually might completely vaporize as it slides, explaining the grooves that appear to gradually fade away.
The scientists actually did a test on Earth, buying a dry ice block at a grocery store and releasing it at the top of a desert dune. Go to my April 2020 link above to see the very cool video.
Several planetary scientists did further combing through many MRO photos of this dune and now think they have spotted examples where the camera actually captured a block as it was sliding downhill.
The photo to the right, taken from the supplementary material to their paper, shows the area in the white box above but this time with plumes rising from three places in one groove. From their abstract:
We present satellite imagery of airborne dust plumes lofted by mobile ice blocks sliding down gullies in 2007, 2012, and 2016, captured by two cameras onboard Mars Reconnaisance Orbiter at nearly the same position in the Martian orbit, demonstrating that the activity is seasonal and predictable. The sliding ice blocks agitate dust resting on the surface, thereby generating easily recognizable billowing plumes of dust. Fine‐grained dust is suspended in the atmosphere where it can travel longer distances before settling, whereas coarse‐grained dust saltates away from gullies, settles, and forms bright fringes around the dark sand of active gullies.
Russell Crater is located at about 54 degrees south latitude in the southern cratered highlands. During the winter it is close enough to the pole so that some carbon dioxide in the atmosphere falls as snow to form patches of dry ice on the south-facing slopes of the dune, which get much less sunlight and are mostly in shadow during the winter months. It appears it is that dry ice that slides down the dune’s slopes.
The support of my readers through the years has given me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Four years ago, just before the 2020 election I wrote that Joe Biden's mental health was suspect. Only in this year has the propaganda mainstream media decided to recognize that basic fact.
Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Even today NASA and Congress refuse to recognize this reality.
In 2020 when the world panicked over COVID I wrote that the 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. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
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.
Please consider supporting my work here at Behind the Black.
You can support me either by giving a one-time contribution or a regular subscription. There are five 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:
5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
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. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.
Click for full image.
Today’s cool image is an update on a previous cool image published in April 2020 about how scientists believe the grooves seen on the slope of a giant dune in Russell Crater on Mars are believed to be formed by frozen blocks of carbon dioxide sliding down the slope when spring arrives. The photo to the right, taken on March 3, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and rotated and cropped to post here, shows these grooves. As I wrote then,
Because the block is sublimating away, the gas acts as a lubricant so that it can slide down the hill. If large enough, the dry ice block will stop at the base of the hill to disappear in a small pit. If small enough, it actually might completely vaporize as it slides, explaining the grooves that appear to gradually fade away.
The scientists actually did a test on Earth, buying a dry ice block at a grocery store and releasing it at the top of a desert dune. Go to my April 2020 link above to see the very cool video.
Several planetary scientists did further combing through many MRO photos of this dune and now think they have spotted examples where the camera actually captured a block as it was sliding downhill.
The photo to the right, taken from the supplementary material to their paper, shows the area in the white box above but this time with plumes rising from three places in one groove. From their abstract:
We present satellite imagery of airborne dust plumes lofted by mobile ice blocks sliding down gullies in 2007, 2012, and 2016, captured by two cameras onboard Mars Reconnaisance Orbiter at nearly the same position in the Martian orbit, demonstrating that the activity is seasonal and predictable. The sliding ice blocks agitate dust resting on the surface, thereby generating easily recognizable billowing plumes of dust. Fine‐grained dust is suspended in the atmosphere where it can travel longer distances before settling, whereas coarse‐grained dust saltates away from gullies, settles, and forms bright fringes around the dark sand of active gullies.
Russell Crater is located at about 54 degrees south latitude in the southern cratered highlands. During the winter it is close enough to the pole so that some carbon dioxide in the atmosphere falls as snow to form patches of dry ice on the south-facing slopes of the dune, which get much less sunlight and are mostly in shadow during the winter months. It appears it is that dry ice that slides down the dune’s slopes.
The support of my readers through the years has given me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Four years ago, just before the 2020 election I wrote that Joe Biden's mental health was suspect. Only in this year has the propaganda mainstream media decided to recognize that basic fact.
Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Even today NASA and Congress refuse to recognize this reality.
In 2020 when the world panicked over COVID I wrote that the 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. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
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.
Please consider supporting my work here at Behind the Black.
You can support me either by giving a one-time contribution or a regular subscription. There are five 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:
5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
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. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.
Wheeeee!!!