Life Will be Hard for Colonists – Kaguya Can’t Find Water on the Moon


It’s been a long-held belief that the Moon is hiding significant quantities of water ice, safe from the Sun’s ablative effects inside shady craters. One such crater is called Shackleton at the lunar South Pole and previous Moon missions have indicated it might hold a large reservoir of ice for all the water needs of future Moon colonists. Alas, the Japanese lunar mission Kaguya (or the Selenological and Engineering Explorer – “SELENE”) has taken a peek into the crater to find… nothing. At least, it hasn’t spotted any significant quantities of surface ice. So where does this leave future lunar colonies?

In 1994, the US Clementine lunar orbiter (a joint venture between NASA and the Ballistic Missile Defense Organization) carried out the “Bistatic Radar Experiment” which involved bouncing radio signals from the probe’s transmitter from the lunar poles. The reflected signal was then received by the Deep Space Network antennae on Earth. Scientists deduced from the reflected signal that volatile ices were present in the lunar regolith, most probably water ice. However, this claim was disputed after a similar experiment was done using the Arecibo radio telescope in Puerto Rico. This time, radio signals were reflected from regions on the Moon bathed in sunlight (where it would be impossible for water ice to survive) and identical results to the Clementine mission were found.

NASA’s 1998 Lunar Prospector also had mixed results. Using its Neutron Spectrometer (NS) instrument, the probe had detected large quantities of water, leading NASA to make the estimate that 3 billion metric tons of water ice was located at or near the surface of the Moon in its polar regions. However, when the mission ended in 1999, the Lunar Prospector was deliberately crashed into a crater in the lunar South Pole in the hope of kicking up a plume of lunar surface material and detecting water ice from Earth. Unfortunately, no water was discovered. (Out of interest, the Lunar Crater Observation and Sensing Satellite, set for launch in April 2009, has a similar suicidal goal to put a divot in the Moon.)

Now, using the Japanese lunar mission Kaguya, scientists have taken the opportunity to have a closer look into the Shackleton crater, the most likely candidate to have a supply of water ice shaded from the Sun. As there is no atmosphere (apart from some very tenuous outgassed chemicals), sunlight cannot be scattered into the bottom of the crater to illuminate its surface. However, scientists have taken images during lunar mid-summer when enough light is scattered off the crater’s upper inner wall to faintly brighten the darkness below.

Although it is very cold inside the crater (-183°C or -297°F), certainly ideal conditions to preserve ice, there is no visual evidence of any surface ice at all.

Although this isn’t great news for future lunar colonists, don’t pack up your Moon buggies quite yet. The Japanese team have concluded that although there is no visual brightening due to ice, water ice may be mixed in low quantities with the lunar dirt. Or there’s simply no ice in Shackleton crater. Either way, I wouldn’t suggest mounting a manned expedition to Shackleton any time soon…


16 Replies to “Life Will be Hard for Colonists – Kaguya Can’t Find Water on the Moon”

  1. That is something of a blow to lunar colonisation hopes – I’d had the impression people considered the existence of water ice on the moon very likely, and I hadn’t heard about the counter evidence. Guess this means we will be hauling a lot more fluids across. Roll on the space elevator…

  2. Sweet! Finally an excuse to start working on my Comet Catcher satellite. Basically it a giant catchers mitt with an ion engine attached (note to self: don’t post your Nobel Prize caliber ideas until after you patent them)

  3. This is harsh news indeed. Think I’ll just join WETI sit on my sofa and wait for an alien to bring me in a nice cup of tea. (Could be a long wait)

  4. The source of the optimism is the scattering of neutrons from hydrogen. The assumption is that the presence of hydrogen atoms (or protons, which are the basis of the common hydrogen isotope nucleus, which is what the neutron scatters off of), equates to the presence of water. This is one source of the optimism with regard to the anticipation of large quantities of water on Mars, though that optimism is bolstered by the assumption that the features on Mars are water-created or modified and the direct detection of relatively small quantities of water ice. We should note, however, that the widespread existence of the mineral olivine on Mars directly contradicts the notion of widespread water since water dissolves olivine. The moon is teaching us a lesson if we are paying attention. The silver lining is that if the moon harbors hydrogen at the poles in some compound form, or if there is an enhanced solar wind flux at the poles, it may be possible that plentiful oxygen in the regolith (45%) can be extracted (solar energy as a power source) and combined with the hydrogen to make water in a reverse electolysis.

  5. Although the evidence has been disappointing, there is still a good chance that abundant ice does exist on the moon. The reason for this optimism is the fact that our solar system as we know it has plenty of ice, and much of it being carried by asteroids. It is inconceivable that, over the time span of billions of years, the moon has never been hit by some of the icy rocks.

    So I’m not cancelling my reservations just yet 🙂

  6. Heinlein once phrased that The Moon Is a Harsh Mistress.

    And I do wonder how an ambitious society has to be constituted. Question: How could deprivation hinder us? – Depriviation is the most familiar phrase prescribing those with the most successful progeny of mankind. “No water ice found yet?”, this is not an insurmountable obstacle.

    No matter how, whether through the supply chain of a communist version of human kind or by the also unrelenting embossing of individuals: a fraction of mankind is able to reach out for and to take over parts of outer space.

    This is a beginnig!

  7. Honestly?

    I’ve never understood how would the water reach the surface to start with. And not be lost to space. For one, impacts generate large amounts of heat in the surface, which kinda prevents water from staying where they happen. So any water that might exist inside a crater would have to get there after the crater was formed. But how? Where would it come from?

    Then there’s the permanent shade thing. It makes sense, but only if the Moon’s axis of rotation never wobbles. Wouldn’t it wobble after major impacts, though? Wouldn’t that kinda make permanent shade areas non-permanent in the long run?

    Unless someone can show me actual moon ice of explain to me a viable way to put these doubts aside, I’m remaining skeptic. In my view, we may find underground ice deposits one day. But superficial? Don’t think so.

  8. Heck you earthlings have to drill for a large percentage of your fresh water, and you live on a plant flush with oceans. I hardly see this as a downer, you may just have to do a little digging to find what you are looking for.

  9. Put some big engines on the space station and orbit the moon for a while to collect some good data. It’s embarassing that 40 years after we’ve been to the moon, we still don’t know the lunar polar regions contain water ice.

    I also hope Lacrosse doesn’t get cancelled – it’s still worth a shot.

  10. There’s all sorts of water on the moon. You just have to drill for it. Any permanent moon facilities should be subterreanean anyway. Surface structures are too dangerous to live in due to gamma rays, micro meteorites, micro dust particles and extreme temperature fluctuations. But yes, there’s alot of water on the moon. It might be combined with sulfer and other compounds. We would be better off searching for deep natural caverns and chasms with some deep scanning radar. We’ve built small cities and military installations underground here on Earth. The Moon underground would provide a stable temperature and comfortable environment to live in. There’s water on the moon, we’ll just have to filter it, but then, maybe we’ll get lucky. Of course, if we don’t get along with each other here on Earth, it may be another couple thousand years before we go back again. It’s already been three generations since we were there last. Or so we’ve been told.

  11. “Put some big engines on the space station and orbit the moon for a while…”

    That’s much easier said than done.

    ISS is not built to take high thrusts, you’d break modules and solar panels off in the first two minutes. Low thrust engine (ion or the like)? That means slowly spiraling up to escape velocity, spending WAY too much time in the VanAllen belts. (Apollo and most other craft cut across them pretty quickly).

    And neither living things, nor most solid state electronics like ionizing radiation very much.

    But let’s say you get there in spite of that. How do you conduct re-supply and crew rotation? The shuttle obviously can’t get to Lunar orbit. Neither can Soyuz, Progress or ATV.

    And then there’s the small matter of getting the kind of instrumentation onto ISS that might confirm Lunar ice, before you try to leave…

  12. Frank G. – you’re right, leave the space station where it is in low earth orbit. The experiment it’s involved in now – to try to bore earth’s population to death – is much too important.

  13. @TD Says:
    October 25th, 2008 at 2:17 pm


    On topic – time to start recycling wee…

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