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Mars’ polar ice canyons are young and the source for mid-latitude ice

Mars' north pole icecap
Mars’ north polar ice cap.

Scientists have now proposed that the giant ice canyons seen at the edges of Mars’ polar ice caps are very young and are also the source of the water that sublimates away when the planet’s rotational tilt (its obliquity) is high, to fall as snow in the mid-latitudes where it forms the glaciers and ice sheets we now find there.

The image to the right, reduced to post here, shows the entire north pole ice cape on the left, with its spiral canyons. The two inserts on the bottom show for scale Hawaii’s Big Island and the Grand Canyon. From the release:

“Erosion formed a huge ice canyon system, and that erosion is a source of the long-known mid-latitude mantles on Mars,” said Rodriguez, lead author of “North polar trough formation due to in‑situ erosion as a source of young ice in mid‑latitudinal mantles on Mars” that appears in Nature Scientific Reports.

The troughs are arranged in a vast spiral pattern covering an area the size of Texas. We find that their growth lateral to katabatic wind (wind that carries high-density colder air from a higher elevation down a slope) directions produced widespread simple intersections, from which the highly complex spiral arrangement emerged, Rodriguez said. “The spiral pattern seen in the troughs is basically an erosional byproduct,” he said. “As the pits grow and intersect over a pre-existing dome-shaped polar cap, the spiral pattern emerges.

“It has long been proposed that sublimation of water ice from the north polar cap during high-obliquity cycles was an essential source of the planet’s mid-latitude icy plains. Our finding identifies the troughs as direct evidence of those sublimation phases,” Rodriguez said.

These spiral trough features formed very recently, in geologic terms: between a few million and 50,000 years ago, Rodriguez said.

This hypothesis, if true, is very important in understanding the long term geological history of Mars. The present theory is that when the obliquity rises to as high of 60 degrees, compared to today’s 25 degrees (similar to Earth’s), the mid-latitudes are colder than the poles, and the ice at the poles then migrates to the mid-latitudes. This paper gives us the place at the poles where the icecap shrinks as that ice sublimates away.

Knowing that these polar canyons are young and the source of the mid-latitude ice scientists can now begin to write the geological history of the polar ice caps themselves. They can also use this information to maybe determine whether the caps are presently in a steady state, as now believed, or growing or shrinking.

The youth of these canyons also suggests that any mid-latitude ice from them is also young, and thus more likely pure water unpoisoned by the toxic perchlorates found in many places on the Martian surface. It will thus be easier to obtain pure drinkable water from them.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!

 

From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

 
Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.

 

“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.

 

All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.

 

Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.

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