Mars Harder and Colder Than Previously Thought

coondoggie writes "Turns out that the surface of Mars is stiffer and colder than previously thought. New observations from NASA's Mars Reconnaissance Orbiter indicate that any liquid water that might exist below the planet's surface and any possible organisms living in that water would be located deeper than scientists had suspected. NASA made the discovery while using the Shallow Radar (SHARAD) instrument on the Orbiter, which revealed long, continuous layers stretching up to 600 miles, or about one-fifth the length of the United States. The radar pictures show a smooth, flat border between the ice cap and the rocky Martian crust, NASA said. On Earth, the weight of a similar stack of ice would cause the planet's surface to sag. The fact that the Martian surface is not bending means that its strong outer shell, or lithosphere, a combination of its crust and upper mantle, must be very thick and cold."

Comments

vapor pressure

[goombah99]

I compiled the first in situ measurements of the annual temp and pressure cylces on mars (viking lander).

I was always surprised by the mars has water debate when it seemed to me the vapor pressure of the atmosphere was less than the vappor pressure of water.

Thus to my mind if mars had water in any abbundance then it had to be bound up in some mixture that was lowering the vapor pressure.

Apparently there may be another possibility: deep very cold storage.

But either way: no available surface water. No canals. no oceans.

Re:vapor pressure

[mbone]

I was also involved in Viking. At that time, we did not know about the long term (30Kyr and longer) cycles in the Martian obliquity and solar insolation. During the cycle the polar regions lose and gain material - the layering at the poles is clear evidence of that.

Mars, as you point out, is at present very close to the triple point of water, but it is below it (so no liquid water). However, at other times in its dynamical cycle, surface conditions are almost certainly above the triple point, as water and CO2 are lost by the poles and put into the atmosphere. So, it seems pretty clear that Mars goes through wet and dry cycles, although the further implications of that are very much a matter of debate.

length clarification

[Anonymous Coward]

> 600 miles or about one-fifth the length of the United States

Or, to clarify, about 236417 Volkswagen Beetles in length.

Sounds familiar

[LineGrunt]

Mars Harder and Colder Than Previously Thought Sounds like one of my ex-girlfriends...

It's to be expected, really...

[FurtiveGlancer]

He is the god of war after all. I'd imagine that tends to make one cold and hard over the millenia.

Lack of flexure observed before

[amightywind]

This was already suspected. The giant volcanic pile of Tharis fails to cause significant flexure of the lithosphere. This has been known since the Viking days. On earth 14000' feet (the height of Mona Loa) is about how much you can load oceanic crust on earth without causing it to sag. On Mars no such sagging occurs, and Olympus Mons is nearly 90000' above the planetary mean! This has been known since the Viking days. The polar observations add another data point, but the result is not a surprise.

Re:Questionable analogy?

[tomhudson]

The simple fact is that, even on its' surface (pun intended), it's an obviously wrong comparison. The fact that an ice sheet that size would bend the earths' crust is, as I pointed out, irrelevent - the same mass only weights half as much on Mars. Even more irrelevant because the earths' crust is floating, so more weight would cause a plate to sink slightly, like getting into a rowboat - Mars has no plate tectonics.

No surface water... today

[symbolset]

But either way: no available surface water. No canals. no oceans.

According to the article the ice cap on mars is in four layers each a 1/4 mile thick roughly. These layers each represent a million year period of deposition.

It follows that either there was liquid water and water vapor on mars to deposit the ice at the pole, or there was a horde of very determined martians with trucks to move it there :). I would go with the canals and oceans theory myself.

So we have roughly a cylinder of ice a mile thick and a thousand miles across on Mars. With the careful application of energy that's more than enough to produce a breathable atmosphere or at least provide for a considerable human habitat.

I am less concerned about finding life on mars than I am with putting it there. We can leave to the exploration of the asteroid belt the discovery that mere interplanetary distances are not an effective barrier to lichens, let alone intelligent life. Besides, the best evidence for fossil life on mars will be found in the Basal Unit under that mile thick ice. That's a lot of digging for a girl in a space suit.

There is no shortage of water at the poles

[Morgaine]

> If there are not subterranean aquifers close enough to the surface to be accessible, then things are going to be very hard-going.

I'm not sure where you got the impression that there is no easy to reach water on Mars.

There are billions of cubic kilometers of water ice quite easily accessible at the poles. Furthermore, it's right there on the surface at the north pole (except during winter when it gets covered by a layer of CO2 ice about a meter thick). At the south pole, water ice lies about 8 meters under the CO2 surface ices. (These numbers are very rough estimates, please note.)

If you want water, just apply heat! The problem of gathering and transportation in that environment is non-trivial, but at least there's no shortage of actual water ice.

They're searching for liquid water because that's more likely to harbor life, but for sustaining human life all we have to do is to live near the poles and melt a continuous supply. What we'd need most is a plentiful supply of energy and good isolation from the dangerous environment.

For more info on Martian polar ices, Wikipedia provides a reasonable summary.