How Much Water is on the Moon?

I have a new post up at Air & Space that discusses the techniques used to sense water remotely and the amounts of water that may be found in the lunar polar regions.  This post was motivated in part by some of the ignorant comments on lunar water that I see on space chat boards.  Comment here if desired.

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14 Responses to How Much Water is on the Moon?

  1. Gary D Miloglav says:

    Thank you! There are several notable people I follow that still believe there are no resources, nor reasons, to go back to the “dusty, useless, ball”.

  2. Gary Church says:

    “I estimate that between 100 million and one billion metric tons of water are present at each pole.”

    I have cited the infographic in figure 10 on page 155 several times on forums when I am allowed to comment as it was a sea change in my worldview when I first saw it:

    The difference in the energy required to lift a mass free of lunar surface gravity compared to the energy required to lift a mass free of Earth gravity is truly mind boggling.

    Lunar resources are the key to human expansion into the solar system.

    Because the Moon is outside the magnetosphere the use of nuclear pulse devices (bombs) there will not result in fallout contaminating the atmosphere of Earth. Nuclear Pulse Propulsion provides Isp numbers in the tens of thousands and would use about 120 gallons of water, or about 960 pounds, per pulse. Freeman Dyson calculated between two and three thousand pulse units would be required for a journey to the outer solar system and back. The amount of fissile material required for each pulse unit would be between 5 and 20 pounds depending on whether plutonium or uranium is used with material for about 200,000 pulse units in the global non-weapon stockpile.

    These numbers break down to roughly enough unused bomb-grade material sitting around right now as a security problem for about 100 missions to the outer planets and each mission would require about a kiloton of water. Each spaceship would also coincidentally require a minimum of a kiloton of cosmic ray water shielding.

    The bomb pits are here waiting to be sent to the Moon by SLS and the water is on the Moon. We can send humans on missions to anywhere in the solar system we want within ten years.
    This is almost completely unknown to the public.

  3. nova9 says:

    Even if there were absolutely no ice deposits at the lunar poles, the lunar regolith would still be valuable because of its high oxygen content. Approximately 89% of the mass of water is oxygen and 86% of rocket fuel is liquid oxygen.

    The presence of water ice, of course, would mean that hydrogen wouldn’t have to be exported from Earth for human survival on the lunar surface or for trans-lunar and interplanetary missions.

    Crewed spacecraft visiting the lunar surface need to be already designed to use liquid hydrogen and oxygen so that when lunar water becomes available, such spacecraft can immediately use lunar fuel derived from lunar resources.

    But it shouldn’t be difficult or too expensive to design and deploy reusable crewed lunar spacecraft into orbit that can utilize propellant manufacturing water depots located at LEO and EML1 such as the ULA’s XEUS concept or Lockheed-Martin’s MADV concept or Boeing’s Altair descent stage modified to be a reusable single staged vehicle.

    But serious funding for such reusable lunar spacecraft needs to begin by 2019, IMO, if crews are to return to the lunar surface in the near future (early to mid 2020s).

    Recurring cost for crewed lunar missions could be significantly reduced if guest astronauts from other space agencies were invited to fly to the lunar surface along with American astronauts — perhaps at a cost of $150 million per astronaut. Two guest astronauts, therefore, could reduce NASA’s cost per lunar mission by $300 million while each foreign space agency would get a chance to place its astronaut on the moon while bringing back perhaps 10 kilograms of lunar samples for their countries for a mere $150 million.


    • Gary Church says:

      “But serious funding for such reusable lunar spacecraft needs to begin by 2019-”

      Well, the New Shepard propulsion module is flying and in my view that qualifies as serious funding. I never ever thought I would be cheering on a billionaire’s suborbital tourist hobby rocket. But as the Blue Moon lander it will fit right on top of the SLS and away we go Marcel. I am drawn to what exists and what will work. I know the SLS will work because it is essentially a space shuttle and Apollo capsule. I know wet workshops will work because of Skylab. I know frozen Low Lunar Orbits (LLO) and Lunar Cyclers will work because the orbital mechanics are mathematically proven. I know cosmic radiation shielding will have to be massive because Eugene Parker says so and I know artificial gravity will be required because of the condition of astronauts returning from the ISS. I know Nuclear Pulse Propulsion is the only practical system for propelling such true spaceships with shields and tethers to remedy dosing and debilitation.
      And I know the Moon is the only enabler to any of it.

      But there are of course unknowns such as storing and transferring hydrogen in space. Harvesting lunar ice is an unknown. And down the line there are increasing technical challenges and obstacles to the various economic engines to enable human space exploration and colonization. GEO telecom platforms, spaceships carrying the nuclear deterrent, and space solar power all are entail unknowns. But “serious funding” must come from somewhere and in my view going cheap is not the path. There is no cheap. Rather, abandoning LEO and other pursuits and redirecting funding toward building a cislunar infrastructure based on lunar resources must become “the horizon goal” and fantasies like Mars have to go on the shelf indefinitely.

  4. George of Modesto says:

    Our planet is a water world. For those who claim
    ‘there’s no water on our Moon’ have given little or no
    evidence to support their theory. We haven’t been to the
    Moon in nearly fifty years. Who can legitimately make this
    True, there’s little water on the lunar “surface”.
    There’s no atmosphere to hold it. How far down have our
    microwave radiometry devices measured? Just common sense
    says that there has to be water in the lower depths of
    the lunar surface. Even Mars has water. Given the age of
    the Moon and the abundance of hydrogen and oxygen on the
    Earth, chances are there are considerable quantities of
    sub-lunar water.
    Water on Earth does not exist solely on its surface.
    Consider the aquifers. Matter has the tendency to seek its
    own level. The Marianas trench is over 36,000 feet deep.
    That’s almost seven miles down.
    What is the cause of lunar quakes? Why are there tides
    on Earth’s oceans? Something to think about.

  5. Gary Church says:

    “Although more orbital measurements would be valuable, it is most critical to get instruments down on the surface of the Moon next, at the poles, in order to make detailed site surveys—information crucial to formulating good engineering decisions about where to place the lunar outpost(s) and how to go about harvesting the Moon’s water-”

    I was very excited about Dr. Spudis’ proposal to hard land sensors:

    And commented that it would be an excellent first mission for the SLS. Those comments from November of 2015 also have me and Marcel arguing about going cheap.

    Would ten or twenty tons of those sensors at the poles improve the data?

  6. Philip Backman says:

    Hi Paul,

    Just wondering about the geometry, how was the Arecibo antenna able to “look into” the far north Cabeus crater?


    • Paul Spudis says:

      You mean “far south”, right?

      The Moon librates in latitude about 6 degrees every month, so we can look beyond the polar limb about 150-200 km, depending on topography. We took bistatic data at the most favorable southern libration.

  7. Bob Goddard says:

    I’m really pleased you’ve posted this, Paul, as it gives me the opportunity to educate some of the less well-read commentators on facebook, too.

  8. Robert Lucas says:

    I had the idea that if the Moon is supposed to have come out of the Earth that the abundant oxygen in its rocks may have come from that if the hydrogen escaped or bound itself to other atoms. Water is supposed to be tightly locked up in the rocks I believe, so tightly that it took them some time to find it. Perchlorate on Mars, as chlorine makes up 55% of seawater with sodium could be the same thing, although with different processes affecting it. At the end of the day you have to access the resources you find! This is long term and difficult.

    • Paul Spudis says:

      Water is supposed to be tightly locked up in the rocks

      We don’t think this for the lunar poles — the idea is that water is added by some process to the cold traps and the temperatures there are too low for any significant chemical reaction with the surface rocks. Thus, we believe that water exists as some free form of ice or frost.

  9. Michael Wright says:

    FYI, Spudis’ outline of his presentation for Jan 10-12 Lunar Science for Landed Missions Workshop at Ames Research Center,
    I hope this workshop will increase interests of other people (ones with extra millions to spend or setting budgets) to do lunar missions. I think we have plenty of Mars stuff.

    Gbaikie commented on Dennis Wingo’s blog in response to my comment of water on the Moon:

    I think the lunar poles has ice, but problem is the proof. If it were true, that there was billion tonnes of ice at north or south lunar pole – that is useless.

    What is useful or proof is that there is 10,000 tonnes within some location and within 1 km radius and it’s within 1/2 meter of the lunar surface.

    There is good case to explore the Moon in order to find minable water. NASA or someone should do that. And once that is done, a decision can made regarding whether or when lunar water can be mined. NASA shouldn’t make such a decision – it should a commercial decision.

    –end quote–

  10. Gary Church says:

    Cold traps with ice were theorized in 1961 but we never did go look. I would guess Apollo landings at the poles near these craters were too difficult. It is interesting to consider if permanent bases on the Moon might have been established thirty years ago if Apollo astronauts had explored one or more of these cold traps and found abundant water ice.

    I hope another thirty years from now there are not people saying, “permanent bases on the Moon might have been established if we had explored those craters and found ice”. How long before we finally go?

    In my view the Blue Moon Lander on the SLS is the best path right now. A robot that can roll into a crater and harvest water and roll back to fill tanks on the lander- and that small nuclear reactor to turn some of the water into propellants. Both the Lander and the reactor are in development right now but what is not being considered is a wet workshop. SLS upper stages in Low Lunar Orbit with cosmic ray shields filled with water would establish a long duration human presence in cislunar space. These workshops can be attached to each other with tether systems to provide artificial Earth gravity and also be used as shielded Cyclers to carry astronauts to and from the Moon.

    We have the Lander and the reactor and we will be sending upper stages that way- we are so close. Need some robots to roll into those craters.

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