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."

vapor pressure

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:Water On Mars

A very interesting read is "Is Mars Habitable?" [audiopod.ca] by Alfred Russel Wallace. Written in 1907 it refutes the then current notion put forward by the astronomer Percival Lowell that Mars had canals, flowing water and plant life.

Re:vapor pressure

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

All in all, bad news for people who hoped that Kim Stanley Robinson's trilogy beginning with Red Mars [amazon.com] would be a reasonable vision of the settlement and terraformation of Mars. If there are not subterranean aquifers close enough to the surface to be accessible, then things are going to be very hard-going.

There is no shortage of water at the poles

> 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 [wikipedia.org].

No surface water... today

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.

Re:No surface water... today

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.

How do you turn ice into a breathable atmosphere for a planet? The atmosphere is 78% nitrogen and 20% oxygen. If you could extract oxygen from the ice, you're still missing 4/5 of your atmosphere. Then of course there's the issue of what happens to all that free oxygen. Oxygen is highly reactive and tends to, well, oxidize whatever it comes into contact with; that's going to scrub it out of the atmosphere. That means that you have to produce vastly more than you'd need just to fill an atmosphere, and that's why it took hundreds of millions of years after photosynthesis became common before Earth had anything like a breathable atmosphere.

Re:

The atmosphere is 78% nitrogen and 20% oxygen. If you could extract oxygen from the ice, you're still missing 4/5 of your atmosphere.

All that you need to breath is about 2 psi partial pressure of oxygen. The nitrogen isn't necessary. Mars has enough gravity to support about 5 psi atmospheric pressure, so it isn't really a problem.

Then of course there's the issue of what happens to all that free oxygen. Oxygen is highly reactive and tends to, well, oxidize whatever it comes into contact with; that's going to scrub it out of the atmosphere. That means that you have to produce vastly more than you'd need just to fill an atmosphere, and that's why it took hundreds of millions of years after photosynthesis became common before Earth had anything like a breathable atmosphere.

It took a long time of oxygen to build up on earth beca

Re:

No, life is not known to exist on Mars. Odds are good some spores made it from Earth, but that doesn't mean they'll catch on anything. A bacteria that never leaves spoil form is just something that takes a long time to die. So there might be life there now

Re:vapor pressure

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

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

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

Re:

Perfectly legitimate measurement, if only you had specified what model and year of Volkswagen Beetle.

And a new endeavour for engineering students to try and hang 236417 Beetles from a bridge.

Sounds familiar

Mars Harder and Colder Than Previously Thought

Sounds like one of my ex-girlfriends...

Re:Sounds familiar

Heh! I'm pretty early in this post so let me show you what I saw, for you ppl with thread view enabled...

Sounds familiar (Score:4, Funny)
by LineGrunt (133002) Alter Relationship on Saturday May 17, @10:19AM (#23445472)

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

and then, right below...

Hmmm (Score:3, Funny)
by Anonymous Coward on Saturday May 17, @10:19AM (#23445476)
"Harder and Colder Than Previously Thought"

Sounds like my wife.

POsted at the same time, so the second is probably a coincidence, not a rip off, but the thing that made me LOL was noticing that the guy talking about his ex-gf used his username, and the married guy posted anonymously. I guess some stereotypes have to be true every now and then if they're going to retain their humor.

Hmmm

"Harder and Colder Than Previously Thought"

Sounds like my wife.

Questionable analogy?

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,

On Earth, a similar stack of ice also weighs twice as much ... it's a questionable comparison from which to draw a conclusion without more information.

Re:Questionable analogy?

Odds may be high that they accounted for the differences. However, this is NASA we are talking about. Odds are also high that they used Kg. for one, and lbs. for the other.

Re:Questionable analogy?

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.

Re:

Rock can compress. I imagine that the effect is relatively easily observed when you are considering the compression over several miles of thickness. The article says little to nothing about what exactly they observed, so it's hard to say if the comparison

There's something wrong with the thought of...

Stiff, cold martians.

It's to be expected, really...

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

Lack of flexure observed before

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:

Good post but it underestimates the fact that the gravity on Mars is about one third of that on Earth (0.37 g), so one can't directly compare the force specific geological features effect on the planet's crust.

Re:

Yeah, but that modeling change is trivial. The poster is correct; Tharis proves that the crust is rigid.

Re:Lack of flexure observed before

Great question! I said oceanic crust. Mount Everest sits atop a *double* thickness of continental crust - the Indian plate thrusting atop Asia to form the Himalaya. This crust is relatively bouyant on the mantle, resulting in mountains about double the height of what is usual. Another curiosity is the height of the high Andes at about 20000'. These mountains sit atop a thickened, bouyent accretion wedge from the Nazca subduction zone. So they are a bit higher than the norm on the continents. The theory is simple isostacy. A mountain's height depends on the density of the material beneath it

Harder and Colder Than Previously Thought?

That's exactly what I said about my ex-wife!