Subterranean glaciers on Mars!

By Phil Plait | November 20, 2008 1:29 pm

In the next weird thing found on — or below — the Red Planet, a ground-penetrating radar on board the Mars Reconnaissance Orbiter has found vast glaciers under the rocky surface. These glaciers are at the bases of mountains and cliffs, and are covered with rubble that may be protecting them from sublimating away. The even cooler thing is that these are at lower latitudes (nearer the Equator) than ever seen before.

“Altogether, these glaciers almost certainly represent the largest reservoir of water ice on Mars that is not in the polar caps,” said John W. Holt of the University of Texas at Austin, who is lead author of the report. “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. In addition to their scientific value, they could be a source of water to support future exploration of Mars.”

Glacier on Mars
This older image shows a glacier that flowed from one Martian crater
at the base of a mountain to another crater. Courtesy ESA/DLR/FU Berlin (G. Neukum).

I still advocate going to the Moon for a while before heading off to Mars, but Mars does have one big advantage: that water locked up in the glaciers is not that hard to tap into. It can be used for drinking, farming, breathing, and even as protection from solar radiation (the hydrogen in water makes a pretty good radiation shield).

These underground glaciers also answer a question that’s puzzled scientists for years: the existence of aprons, or gently sloped regions surrounding tall features on Mars. Now it seems clear that the ice at the base of these cliffs and mountains lubricated rubble descending from higher up, so instead of getting big piles, the rubble forms a smoother decline. The radar reflections from aprons indicates they are indeed a thin layer of rubble on top of thicker ice.

We’ve known for decades that Mars has water ice. What we’re learning now is the extent of it, how deep it goes, how it’s placed across the surface, and even how wet Mars was in the past. All of this builds us a picture of a once-dynamic planet, and one that still has lots of surprises waiting for us, literally just below the surface.

CATEGORIZED UNDER: Cool stuff, NASA, Science

Comments (28)

Links to this Post

  1. Massive Martian Glaciers | Vault9 Blog | November 20, 2008
  1. James

    Phil I couldn’t find an email address for you, so I’m posting this here (an update on the Texas Science standards fun). I think its the best use of the word retrograde I’ve seen in a while:

  2. Todd P.

    i got chubs for this piece of information.

  3. elgarak

    I knew it!

    “Total Recall” was correct!


  4. Metre

    When I first saw the Mars Express photo that you show, it was billed as a debris field left over from an ancient glacial flow. I remember thinking that it looked more like rubble and debris covering an existing glacier. Turns out my intuition may have been right. There is also a large alluvial fan structure above the crater, just to the right of the mountain. Probably another glacier that flowed down from the plateau.

  5. mocular

    the hydrogen in water makes a pretty good radiation shield

    Huh? I don’t understand.

  6. Clayton

    excellent! so we wont need to build canals after all.

  7. Shnakepup

    “Red Mars” Trilogy anyone?

    (you just wait – the aquifer outflows of the ’61 revolution will be BRUTAL…)

  8. Stark

    mocular –

    Hydrogen does a good job of absorbing various kinds of ionizing radiation (which is the kind that destroys living tissues). What happens, in a vastly simplified explanation, is that the high speed charged particles that make up ionizing radiation impact the hydrogen atoms in water – which slows down the particles. Slower particles mean less energy, less energy means less damage to living tissues – hence we consider water to make a decent shield against various kinds of ionizing radiation.

    If you want to learn more you can start here
    That’s actually not a great laymans introduction though, sorry.

  9. jest

    Very cool. I like that the first crater is sort of a “hanging trough” which, on Earth, is where a valley is cut into a mountain and the valley intersects with a deeper valley also cut by a glacier. In this case, obviously not quite the same process but where one crater ends and the next one begins, it looks the same as a hanging trough.

  10. But I wanna go to Mars now! [/child]

  11. RE: “the hydrogen in water makes a pretty good radiation shield”.

    The atoms of liquid hydrogen are particularly good as a screen for galactic cosmic rays because they don’t fragment into secondary particles as much as heavier elements — like lead — do when bombarded by high-energy radiation. Those secondary particles could be just as harmful as space radiation itself. Generally high-mass density materials, usually of high atomic number, are not good choices for shielding the spacecraft because, when struck by the primary positive ions, the nuclei of these materials fragment and produce a shower of secondary radiation that includes more charged particles, photons, and neutrons, and the thicknesses of heavy shielding material necessary to stop these becomes excessive from a weight standpoint.

    Polyethylene is a good shielding material because it has high hydrogen content, and hydrogen atoms are good at absorbing and dispersing radiation. In fact, researchers have been studying the use of polyethylene as a shielding material for some time.

    Click on my name for the link to the NASA article on Shields to Protect Future Space Crews.

  12. Mu

    Sorry, the “hydrogen makes a good radiation shield” is flat out wrong when talking high energy cosmic radiation. The only thing that helps is mass, and water is about as low density as you can get. Sure, you can hide under 60 ft of water as well as under 12 ft of dirt or 6 ft of lead, but it makes for a very cumbersome top cover, unless you plan on tunneling deep into a glacier for your living quarters. In which case you better hope your glacier ain’t moving much.

  13. Click on my name again for the link to another article by NASA on the subject of Plastic Spaceships.

  14. Mu, the solar wind and other events typically give out relatively low energy radiation compared to galactic cosmic rays. Ice is excellent at absorbing neutrons, too.

  15. Stark

    Mu – While Phil has already pointed out that we’re not really concerned with high energy cosmic rays… water as a radiation shield on Mars makes MUCH more sense than using lead or even dirt. You’d have to transport that 6ft of lead to mars which is less than ideal. You need earthmoving equipment to put 12 ft of dirt on top of your shelter. All you need for the water shelter is a pump, a heat source to melt ice, some flexible piping and water bladders. You would need these water system items even if you decided to use dirt as a radiation cover and since you can use the water storage system as radiation shielding it makes sense to do so and not have to bring the added weight of earthmoving equipment as well – at least for an initial colony. It would of course make sense for later mission to bring earthmoving equipment – since they wouldn’t need to bring basic life support systems as they’d already be
    in place.

  16. IVAN3MAN

    I found this picture on the NASA web-site in an article titled:

    Digging In and Taking Cover
    Lunar and Martian dirt could provide radiation shielding for crews on future missions.
    New Home on Mars
    Click on the picture to link to the article.
  17. mk


    In an earlier post you said this:

    …going back to the Moon can benefit all of space exploration and science if done properly.

    Could you please explain what “done properly” means in this instance?

  18. mocular

    Stark & IVAN3MAN:


  19. Crudely Wrott

    I’ve been anticipating such definitive measurements. After all, Mars is not that much farther from the Sun that Earth is and previous investigations have indicated the presence, or the effects, of water since we started looking. Way cool. Water is good. If there is no water there, you must take some with you.

    A song comes to mind:

    “There’s a great, hot desert
    South of Mexicali.
    If you don’t have the water
    Boy you better not go.

    I can see that you love her
    By the look in your eye, boy.
    She’s the rose of the desert,
    In old Mexico.”

    I think that we should establish a working relationship with a close celestial body (read: Moon) before casting off for more distant shores. In the same way that we learn to creep before we learn how to brace ourselves against a wall and pretend to walk. Just because we perceive Mars as more seductive than the Moon does not implicate that the Moon could not be an instructive and reliable mistress.

    We are now learning lessons on the ISS. Lessons that are a direct result of all our previous experience in space. Mercury, Gemini, Apollo and on to our present understanding. In order to go far, we must know how; not hypothetically, but by virtue of experience. The Moon is the most obvious training ground. Not to mention that it is not only very close, but it is also just far enough away. Let us test ourselves.

  20. LC

    The catch with using lead or other dense metals for charged particle shielding is that they have a nasty problem of generating Bremsstrahlung radiation – meaning that your ‘space crew’ now gets blasted by X-rays. A doctors X-ray machine work by roughly the same principle (charged particles striking a metal target).

    As mentioned by Ivan3, for particle radiation (cosmic rays) you want something with lots of hydrogen in it – water, plastics, etc. However – hydrogen materials are fairly useless against EM radiation (gamma and X-rays). This is where you need the dense materials – lead, tungsten, etc.

    There is a basic overview and some basic equations at ‘Atomic Rocket’. – Radiation and Shielding – Storm Cellars (aka Biowells)

  21. Nigel Depledge

    Aw. LC beat me to it. I was gonna say about the Bremsstrahlung.

  22. BigBob

    Shnakepup quothe – “Red Mars” Trilogy anyone?

    Yes indeed. In fact “Red Mars” is a favourite: Kim Stanley Robinson’s awesome descriptions of the unmanned rover routing past navigation beacons to ferry water to the camp, and the automated water extraction station are very atmospheric for me. They mine ice blocks and the plant refines the water until it’s pure. Think I’m going to have to read it again.

  23. Gary Ansorge

    Mars: the new goal post,,,

    I wonder why anyone would have ever doubted there was subterranean water on MArs? Earth has lots of hydrogen locked up in minerals such as hydrides and oxygen in oxides. Both elements are highly reactive and readily bond with a wide range of metals. They are thus conserved and protected from solar wind dispersal.
    Of course, it’s a LOT easier to retrieve water from underground reservoirs than to extract it from oxides/hydrides, so this discovery is really exciting, from a utilization point of view.

    I expect we’ll find a lot of subterranean Lunar water, when we finally have geo(Luna?)physicists poking around on the moon.

    We just need to go and stay there,,,

    GAry 7

  24. Gary Ansorge

    PS: those are really AWESOME pics,,,

    Gary 7

  25. Randy A.

    FYI — a pile of rubble with a core of ice is called a rock glacier. Based on the photograph and your description, the term would fit for these features on Mars.


  26. Scottso

    But what about the martian bacteria and microbes that will wipe out any future pioneers! We have no resistance to martian microbes and it will make our superior technology irrelevant!!! 😉

  27. MarsDirect

    I’m curious about this push to go to the moon first, and then Mars. I read Robert Zubrin’s “The Case for Mars”, and his plan sounds reasonable, and the moon seems to pose significant problems for human colonization — it has no significant quantities of natural resources to support a large base. Everything needed to survive there would need to be trucked up from Earth. And it wouldn’t make sense to use the moon as a launch platform to go to Mars or elsewhere either, as the fuel and hardware would have to first be launched from Earth again, assembled on the moon (or in orbit around the moon). Using the moon as an intermediate step to going to Mars or elsewhere will delay planetary exploration by decades, cost huge amounts of money, and add more complexity and risks, I think. Granted, I haven’t read any rebuttals to Zubrin’s idea, and I’m open to suggestions. But so far, it seems to me that the moon, lovely as it is — and an excellent platform for giant telescopes — does not do much for us in terms of human exploration or colonization.


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