November 22, 2008
Massive Mars Glaciers Tempting Target For Global Warming

Good news for future human settlement of Mars: a supply of water for Mars colonists will not be a problem.

AUSTIN, Texas—Vast Martian glaciers of water ice under protective blankets of rocky debris persist today at much lower latitudes than any ice previously identified on Mars, says new research using ground-penetrating radar on NASA's Mars Reconnaissance Orbiter.

Because water is one of the primary requirements for life as we know it, finding large new reservoirs of frozen water on Mars is an encouraging sign for scientists searching for life beyond Earth.

The concealed glaciers extend for tens of miles from edges of mountains or cliffs and are up to one-half mile thick. A layer of rocky debris covering the ice may have preserved the glaciers as remnants from an ice sheet covering middle latitudes during a past ice age.

"Altogether, these glaciers almost certainly represent the largest reservoir of water ice on Mars that's not in the polar caps. Just one of the features we examined is three times larger than the city of Los Angeles, and up to one-half-mile thick, and there are many more," said John W. Holt of The University of Texas at Austin's Jackson School of Geosciences, lead author of a report on the radar observations in the Nov. 21 issue of the journal Science.

"In addition to their scientific value, they could be a source of water to support future exploration of Mars," said Holt.

So would it be better to melt all that ice? Some of the water would evaporate into the atmosphere providing Mars with a higher atmospheric pressure. But it is not clear to me that would help. The amount of radiation reaching the surface would probably still be so high that underground colonies would continue to make the most sense. If the water is kept frozen then colonies could be located around glaciers and only melt as much water as needed.

To make Mars a full outside-living planet where can the oxygen come from? The outer planets seem to have little oxygen. Can anyone point to abundant sources of oxygen in this solar system outside of the Earth? The Mars glaciers are mostly oxygen since water is made from 2 hydrogens and an oxygen. But I doubt enough oxygen is in that water to support a high atmospheric pressure.

Neptune's moon Triton seems like the best place to go (leaving aside energy costs and time) to get oxygen and nitrogen for a Mars atmosphere. We could remove Triton's surface and transport it to Mars for the nitrogen and oxygen.

As with Pluto, 55% of Triton's surface is covered with frozen nitrogen, with water ice comprising 15–35% and dry ice (frozen carbon dioxide) forming the remaining 10–20%.

But does anyone know how much mass of nitrogen and oxygen are on Triton as compared to how much would be needed to give Mars an atmospheric pressure similar to that of Earth?

Or does anyone have a good source for how else enough oxygen and nitrogen could be found to make the Mars atmosphere capable of supporting humans outside?

Update: James Bowery points me to a problematic report on why Mars lost its atmosphere in the first place. David Brain of UC Berkeley says irregular magnetic fields on Mars cause pieces of the Martian atmosphere to pinch off and get blown away by the solar wind.

Brain was scrolling through archival data from Global Surveyor's particles and fields sensors. "We have measurements from 25,000 orbits," he says. During one of those orbits, MGS passed through the top of a magnetic umbrella. Brain noticed that the umbrella's magnetic field had linked up with the magnetic field in the solar wind. Physicists call this "magnetic reconnection." What happened next is not 100% certain, but Global Surveyor's readings are consistent with the following scenario: "The joined fields wrapped themselves around a packet of gas at the top of the Martian atmosphere, forming a magnetic capsule a thousand kilometers wide with ionized air trapped inside," says Brain. "Solar wind pressure caused the capsule to 'pinch off' and it blew away, taking its cargo of air with it." Brain has since found a dozen more examples. The magnetic capsules or "plasmoids" tend to blow over the south pole of Mars, mainly because most of the umbrellas are located in Mars' southern hemisphere.

So how can we create a strong consistent magnetic field on Mars capable of retaining an atmosphere for a long time? Bring iron in from elsewhere in the solar system? If so, where?

Share |      Randall Parker, 2008 November 22 07:16 PM  Space Exploration


Comments
Sanjay said at November 23, 2008 12:04 AM:

If you're already going out that far to find nitrogen, then why not just divert some ammonia-ice(NH3) comets or other similar bodies from the Oort Cloud and Kuiper belt. At least cometary orbits seem to take them in closer to the Sun periodically, which means that there should already be plenty of inbound comets that can be diverted to Mars anyway. They just need the right nudge to have them rendezvous with the planet. I'm wondering if there are even any conveniently large ammonia bodies in the asteroid belt nearby. After all, we do know that Saturn's rings are made of ammonia-ice chunks, although these might be energetically expensive to extract, because of Saturn's huge gravity.

Randall Parker said at November 23, 2008 8:04 AM:

Sanjay,

I do not think we should go somewhere to find nitrogen unless we are going to get oxygen out of the trip as well.

Russ said at November 23, 2008 9:39 AM:

How hard IS it to start up a sustainable magnetic field of tremendous magnitude?

Matt Metcalf said at November 24, 2008 3:22 PM:

You don't actually have to do much to get oxygen to Mars... it has a lot of it already. You just need to release it from the rocks... there's a lot of iron oxide (rusted iron) which is why the planet looks red. If you could separate the iron from the oxygen, you'd gain two useful products.

Engineer-Poet said at November 25, 2008 3:47 PM:

Perhaps you could reduce the iron, but how would you keep it from rusting again?  You'd have to put it deep in the crust.

Reheating the core might help with a magnetic field, but it might be easier to just wrap a big wire around the equator and run a current through it.  Or maybe better:  orbit a cable around the equator and energize it, using magnetic pressure to levitate it and use it as an anchor for skyhooks.

Adam said at November 30, 2008 2:49 AM:

Hi All

Plasmoid loss of atmosphere is very slow in present solar wind conditions. Mars's early atmosphere would've been lost when the solar wind was much stronger in the first billion years of the Sun's life. Thus it's not a terraforming issue.

As for radiation, contrary to the over-imaginative Press and bad movies, most protection is from a dense atmosphere - 10 tons of air covers every square metre of Earth's surface. That's what protects us, not the magnetic field. Mars's lighter gravity means the same atmospheric pressure needs 1/0.378 times the air mass over-head. Mars's surface area is 28.3% of Earth's, so the total air mass needed for one atmosphere of air pressure is 76.5% of Earth's (5,270 trillion tons) - thus Mars needs 4,031 trillion tons.

Triton has nitrogen ice, but Titan has nitrogen gas. Saturn is 3 times closer than Neptune and Titan is further out of the gravity well. Since Titan's gravity is 0.137 of Earth, and its surface pressure is 1.5 bar and 98% nitrogen, that means there's 11 times the gas mass over 0.1634 the area. Thus Titan has 2.3 times Earth's mass of nitrogen. Just 25.2% of Titan's air mass would give Mars an equivalent pressure of nitrogen to Earth.

Just how much water is needed to make the oxygen needed on Mars? If we give the same partial pressure some 6,420 kg of O2 is needed per square metre. Water's molecular mass is 18.015, of which 2.016 is hydrogen and 15.999 is oxygen. Thus 7,229 kg of water is needed on every square metre. That translates into 7.86 metres of ice per square metre, almost 26 feet. Since those newly discovered glaciers represent about 10-15 metres of water over the whole planet I'd say there's definitely enough water for oxygen.

Adam said at November 30, 2008 3:25 AM:

I missed a part of Randall's question - how much ice is needed from Triton. About 130 tons of N2 ice per square metre of Triton is needed for the same pressure on Mars as on Earth. Roughly, the glaciers of the stuff on 55% of Triton need to be at least 230 metres thick. Quite a mining effort. Nitrogen ice is 12% denser than water ice, but has to be kept a lot colder. Wrapped in reflective foil it shouldn't out-gas too much on the way to Mars.

Randall Parker said at November 30, 2008 11:00 AM:

Adam,

Thanks a lot for your answers.

So given nanotechnology to support a massive engineering effort in space and some decades of time we could probably terraform Mars and make it have an Earth-like atmosphere.

Should we add more mass to it from the asteroid belt before going down that path? Or does the asteroid belt lack the needed mass?

Also, should we do some engineering to create massive reflectors in Mars high orbit to focus enough light on Mars to make its level of sunlight closer to that of Earth? Or could we get by on putting some greenhouse gases into the atmosphere? I would expect that it just would always seem dim outside at noon without more light reflected from a larger area around Mars.

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