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Space: Shallow ice sheets discovered on Mars could aid future astronauts

Introversion

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Exposed ice on steep slopes can also help reveal the Red Planet’s climate history

Science News said:
Martian ice has a thin skin. The newly discovered exposure of ice on steep banks suggests that the Red Planet’s ice sheets are buried by just a meter or two of soil, researchers report in Science January 12.

“What’s new and exciting here is that these ice sheets start quite shallowly,” says planetary scientist Colin Dundas of the U.S. Geological Survey in Flagstaff, Ariz. That could be good news for future astronauts hoping to use that water to drink, or to create oxygen to breathe or make fuel for returning spacecraft (SN: 1/20/18, p. 22).

Dundas and his colleagues used the Mars Reconnaissance Orbiter satellite to observe eight regions where steep slopes called scarps seem to reveal ice. In 2008, the Phoenix Mars lander revealed ice in regions close to the planet’s north pole (SN Online: 6/20/08). But these scarps were closer to the equator, at latitudes of about 55° north or south.

High-resolution images showed that the ice is organized into thin layers. Dundas says these layers probably originated as snowfall millions of years ago, when the north pole pointed in a different direction.

“It’s essentially giving a cross section through recent history,” Dundas says.

...
Click to expand...

Hmmm, not sure I understand the bolded part of the above. I realize that Earth's "magnetic north" flip-flops periodically, and I know that Earth wobbles on its axis of rotation, but I thought the latter was a small effect and due to changes in distribution of water on Earth's surface.

What could cause Mars' axis to change so dramatically?
 
Woollybear

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I believe Mars had a bizarre sort of dynamo collapse event. My guess is this is connected to the N pole comment.

See the link. This may relate.

ORIGIN OF THE MARTIAN CRUSTAL DICHOTOMY?
Geophysical modeling suggests that a Pluto-sized body may have slammed into Mars early in its history, erasing the cratering record of half the planet and leaving behind the low-lying, flat volcanic plains that now form the northern lowlands of Mars.
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http://www.planetary.org/blogs/emily-lakdawalla/2008/1710.html
 

blacbird

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Introversion said:
What could cause Mars' axis to change so dramatically?
Click to expand...

Consensus among planetary astronomers is that it is due to the absence of a large satellite body. Earth's moon exercises a strong gravitational control on the parent planet's rotational axis. Mars doesn't have that.

It is still curious, however, that the current Martian axis tilt is very similar to that of Earth. Current coincidence? Maybe.

caw
 
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Any spinning body precesses (like a top) in the presence of a gravitational field, and therefore the direction of it axis of rotation will change. In addition, the angle of obliquity changes with time. Both of these change the direction of the axis and can trigger changes in climate, perhaps even enough to bring accumulating snow to low latitudes? It's not clear to me that the article is implying a change in axis direction outside of the generally expected variation through time--do you think that it is?
 
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GeoWriter said:
Any spinning body precesses (like a top) in the presence of a gravitational field, and therefore the direction of it axis of rotation will change. In addition, the angle of obliquity changes with time. Both of these change the direction of the axis and can trigger changes in climate, perhaps even enough to bring accumulating snow to low latitudes? It's not clear to me that the article is implying a change in axis direction outside of the generally expected variation through time--do you think that it is?
Click to expand...

I lack an idea of what "generally expected variation" means in this situation -- sounds like the snowline could reasonably be expected to shift significantly. That this is expected wasn't obvious from my read of the article, but I guess that's assumed knowledge for the reader?
 
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Perhaps the shift in snowline is not so much expected as offering evidence for how climate might vary as a function of the expected variations in obliquity. Neither celestial mechanical modeling or climatic modeling are areas of expertise for me, but here are some general thoughts on the issue that I found. https://hirise.lpl.arizona.edu/ESP_034132_1750
 
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