Spring arrives on the northern polar cap of Mars
Click for full image.
Cool image time! It is now spring in the northern hemisphere of Mars, and the first bits of sunlight are finally reaching its north polar ice cap. During the winter, as happens each Martian year, that polar cap of water ice gets covered by a thin mantle of dry ice no more than six feet thick. Moreover, this mantle doesn’t just cover the ice cap, it extends south as far as about 60 degrees latitude, covering the giant sea of dunes that surrounds the ice cap.
When spring comes that mantle begins sublimate away, with its base first turning to gas. When the pressure builds up enough, the gas breaks out through the frozen mantle’s weakest points, usually the crest or base of dunes or ridges, leaving behind a dark splotch caused by the material thrown up from below that contrasts with the bright translucent dry ice mantle.
Each year for the past decade scientists have been using the high resolution camera on Mars Reconnaissance Orbiter (MRO) to monitor this sublimation process. The photo above, taken on February 24, 2021 and cropped, enlarged, and brightened to post here, marks the start of this year’s monitoring program. Dubbed informally “Buzzell” by Candice Hansen of the Planetary Science Institute in Arizona, it shows dunes with a round pedestal crater just right of center. Though almost everything when this picture was taken is still covered by that dry ice mantle, in the lower left is a single splotch, the first breakout of CO2 gas that marks the beginning of the annual disappearance of this dry ice.
Last Martian year I repeatedly posted images of Buzzell to illustrate this annual process. The second image below was taken on April 4, 2019, at about the same comparable time in spring.
Click for full image.
As you can see, that first dark splotch in this year’s image is close to but not at the same place as a similar splotch two years previously. Both were on dunes, and this change is probable because this process causes slow changes in those dunes each year, meaning that the weak spots are not necessarily going to occur at the same spot each year. As Hansen explained to me recently,
With numerous Mars years we are now looking at interannual variability and the relationship of activity level to dust storms. Also, the number and size of new alcoves is different every year so we are looking at the specifics of the meteorology and snowfall.
I would expect to see splotches on the north side of the pedestal crater this year, as shown by the image from the last Martian spring. Whether they occur in the exact same places is exactly what Hansen wishes to find out.
The wider photo below provides some interesting context. Buzzell is located a little over a mile from the 1,500 to 3,000 foot high edge of the polar ice cap, at a location where each spring avalanches occur so frequently that MRO often catches them as they happen.
That plateau at the pedestal crater is likely bedrock, making it a likely stable site for building a hotel and viewing site for watching those avalanches, just like cruise ships take tourists to watch the icebergs calving off of glaciers in the inside passage of Alaska.
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.
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Click for full image.
Cool image time! It is now spring in the northern hemisphere of Mars, and the first bits of sunlight are finally reaching its north polar ice cap. During the winter, as happens each Martian year, that polar cap of water ice gets covered by a thin mantle of dry ice no more than six feet thick. Moreover, this mantle doesn’t just cover the ice cap, it extends south as far as about 60 degrees latitude, covering the giant sea of dunes that surrounds the ice cap.
When spring comes that mantle begins sublimate away, with its base first turning to gas. When the pressure builds up enough, the gas breaks out through the frozen mantle’s weakest points, usually the crest or base of dunes or ridges, leaving behind a dark splotch caused by the material thrown up from below that contrasts with the bright translucent dry ice mantle.
Each year for the past decade scientists have been using the high resolution camera on Mars Reconnaissance Orbiter (MRO) to monitor this sublimation process. The photo above, taken on February 24, 2021 and cropped, enlarged, and brightened to post here, marks the start of this year’s monitoring program. Dubbed informally “Buzzell” by Candice Hansen of the Planetary Science Institute in Arizona, it shows dunes with a round pedestal crater just right of center. Though almost everything when this picture was taken is still covered by that dry ice mantle, in the lower left is a single splotch, the first breakout of CO2 gas that marks the beginning of the annual disappearance of this dry ice.
Last Martian year I repeatedly posted images of Buzzell to illustrate this annual process. The second image below was taken on April 4, 2019, at about the same comparable time in spring.
Click for full image.
As you can see, that first dark splotch in this year’s image is close to but not at the same place as a similar splotch two years previously. Both were on dunes, and this change is probable because this process causes slow changes in those dunes each year, meaning that the weak spots are not necessarily going to occur at the same spot each year. As Hansen explained to me recently,
With numerous Mars years we are now looking at interannual variability and the relationship of activity level to dust storms. Also, the number and size of new alcoves is different every year so we are looking at the specifics of the meteorology and snowfall.
I would expect to see splotches on the north side of the pedestal crater this year, as shown by the image from the last Martian spring. Whether they occur in the exact same places is exactly what Hansen wishes to find out.
The wider photo below provides some interesting context. Buzzell is located a little over a mile from the 1,500 to 3,000 foot high edge of the polar ice cap, at a location where each spring avalanches occur so frequently that MRO often catches them as they happen.
That plateau at the pedestal crater is likely bedrock, making it a likely stable site for building a hotel and viewing site for watching those avalanches, just like cruise ships take tourists to watch the icebergs calving off of glaciers in the inside passage of Alaska.
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.
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