Scientists discover that mid-sized dunes near Mars’ north pole move
Scientists using images from Mars Reconnaissance Orbiter (MRO) collected over six Martian years (6.5 Earth years) have found that the mid-sized dunes dubbed mega-dunes near the north pole actually do move from year to year, unlike similar sized dunes elsewhere on the planet.
Megaripples on Mars are about 1 to 2 meters tall and have 5 to 40 meter spacing, where there size falls between ripples that are about 40 centimeters tall 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 comparison (average of 0.13 meters per Earth year), some of the nearby ripples were found to migrate an average equivalent of 9.6 meters (32 feet) per year over just 22 days in northern summer – unprecedented rates for Mars. These high rates of sand movement help explain the megaripple activity.
Previously it was believed that such dunes were static planetwide, left over from a time when Mars’ atmosphere was thicker and could then move them more easily. This data however suggests that the winds produced over the north pole when the carbon dioxide in the atmosphere freezes in winter and sublimates back to a gas in summer are sufficient to shift these dunes in the surrounding giant Olympia Undae dune sea.
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Scientists using images from Mars Reconnaissance Orbiter (MRO) collected over six Martian years (6.5 Earth years) have found that the mid-sized dunes dubbed mega-dunes near the north pole actually do move from year to year, unlike similar sized dunes elsewhere on the planet.
Megaripples on Mars are about 1 to 2 meters tall and have 5 to 40 meter spacing, where there size falls between ripples that are about 40 centimeters tall 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 comparison (average of 0.13 meters per Earth year), some of the nearby ripples were found to migrate an average equivalent of 9.6 meters (32 feet) per year over just 22 days in northern summer – unprecedented rates for Mars. These high rates of sand movement help explain the megaripple activity.
Previously it was believed that such dunes were static planetwide, left over from a time when Mars’ atmosphere was thicker and could then move them more easily. This data however suggests that the winds produced over the north pole when the carbon dioxide in the atmosphere freezes in winter and sublimates back to a gas in summer are sufficient to shift these dunes in the surrounding giant Olympia Undae dune sea.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows 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. 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. Only now does it appear that Washington might finally 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.
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
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Cortaro, AZ 85652
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