Bi-static radar search for lunar water fails

By Phil Plait | September 13, 2009 6:00 pm

Over at Universe Today, Nancy Atkinson is reporting that an experiment looking for water ice under the lunar surface has failed.

I wrote about this observation a little while ago: using radar, NASA’s Lunar Reconnaissance Orbiter and the Indian probe Chandrayaan-1 were going to sweep the crater Erlanger to look for a signal reflection indication the presence of ice. However, Chandrayaan-1 was already well on its way to its final malfunction, and the observations didn’t work. Go to UT for the details.

Bummer. But not all is lost: soon, the LCROSS mission will slam a massive weight into the Moon which will hopefully dislodge any of the ice that’s there, and maybe we’ll get our answer. Unless the Moon doesn’t want us too, of course.


Comments (18)


    Err… I think that should be indicating the presence of ice, not “… indication the presence of ice.” ūüėČ

  2. Buzz Parsec

    In case anyone is confused (as I was until I read the article), the search failed in the sense that the experiment wasn’t done correctly so got no useful data, not that the search worked but found no water. (The problem was Chandrayaan-1’s star trackers were breaking down, and it wasn’t pointing in the right direction.)

    It would be really really good to find water on the Moon, because it can be used to support people there (growing food, creating breathable O2, etc.) but even more importantly, it can be broken down into H2 and O2 for rocket fuel, using solar powered electrolysis. Being able to make fuel on the moon would mean you wouldn’t have to launch it from Earth and land it on the Moon, make Moon exploration drastically cheaper. And Moon-derived fuel could be launched into Lunar orbit or to the Earth-Moon Lagrange points much more cheaply than from the surface of the Earth and could then be used for other destinations.

    Obviously, there would be an enormous cost in R&D to make this practical, but in the long run, in space flight, mass is money, and not having to launch all your fuel from Earth is a huge win.

  3. gruebait

    From the Examiner (at the link in the above link):

    Purposefully crashing something into the moon just to watch what happens is akin to a schoolboy cutting up a live frog to see what makes it jump.

    To see such things written by a putative grown-up is just…disturbing.

    Anyway, it’s obvious that we’ll just have to zip out to the Kuiper belt and grab an icy comet or two, and drop them in a polar crater. No problem, right?

  4. Gary

    Those objecting to crashing a small object on to a lifeless hunk of rock are probably worried about their fellow moonbats.

  5. The way things are going politically… maybe my children will find a use for that water that may be there :(

    It doesn’t look like we will be heading back there any time soon. I’m only 44, and I doubt that we will be back in my lifetime.

  6. Flying sardines

    @ 4. Gary Says:

    Those objecting to crashing a small object on to a lifeless hunk of rock are probably worried about their fellow moonbats.

    LOL! The winning post so far by me.

    I hope we (the West generally & NASA specifically) do go back to the Moon & soon. I hope LCROSS works well too.

    As for (#3 Gruebait) grabbing a comet from the Edgeworth-Kuiper belt : Well there are asteroids a lot closer than that in the main asteroid belt that could serve equally well.

    Even some of the outer moons of the gas giants too. Plus there’s always short-period comets here. No need to go out quite that far – although it would be cool to do so anyway! :-)

  7. Ray

    Bi-static radar? So it goes both ways? :)

  8. Hmm

    My grandparents are concerned that said impact will knock the moon out of orbit and kill us all, and that any reassurances to the contrary can’t be trusted because “they’ve never done it before so how do they know.”


  9. Ray


    How exactly do we *know*?

  10. Vince Charles

    Gary (#4),

    Your post says more about your understanding than anyone else’s.

    The Examiner is a chain of conservative papers, and regularly mocks environmentalists (among others). Thus, the quote is an attack on science- the writer assumes NASA is ‘just tryin’ sumthin’,’ and is thus to be attacked. It is gruebait who reads this correctly, not you, Gary.

    NASA (by which I include outside experts doing independent inquiry and repeatability) has done numerous analyses indicating at least some water should be there, though they differ on how much. Then, multiple probes have indicated different signs of water, including a Department of Defense experiment (moonbats, all of ’em).

    However, the water evidence from these missions is inconsistent. Most are indirect signatures; one direct attempt found none, but that could’ve been procedural error. Missing a water-rich area, seeing only a water-poor area. In hindsight, LCROSS will address all these ambiguities, and will hopefully be the definitive experiment.

    And yet, The Examiner thinks we (including the DoD) are “a schoolboy,” tryin’ sumthin’. Do you agree, Gary, now that I have corrected your (and The Examiner’s) misinformation?

  11. Chris A.

    Only because IVAN3MAN missed an opportunity for pointless pedantry: Shouldn’t that be “Unless the Moon doesn’t want us to” (not “too”)?

  12. Chris A.


    “How exactly do we know (that LCROSS won’t knock the Moon out of orbit)?”

    The same way we know that a mosquito hitting the windshield of a freight train won’t derail the train. Except that LCROSS’s mass compared to the Moon is much, MUCH smaller than the mosquito’s when compared to the train.

  13. JT


    Perhaps you should re-read Gary’s post. Or read it for the first time, since your post doesn’t convince me that you actually did.


    @ Chris A. (#11),

    Yeah, well, er… I must have missed that due to it being late (early hours) here in the U.K.; that’s why, at least, two proofreaders are usually employed. ūüėČ

    Anyway, I did a quick, back-of-the-envelope calculation and I’ve worked out what affect would the combined impacts from both projectiles have on the Moon…

    The momentum (P = mv) of the two impactors are:

    Mass — LCROSS Shepherding Spacecraft: 866 kg (1,909 lb) (max.); Centaur at impact: 2,366 kg (5,216 lb) (max.)*

    Velocity at impact (both objects): 2,500 m/s*

    ∴ [2,366 (m1) × 2,500 (v1)] + [866 (m2) × 2,500 (v2)] = 8,080,000 N⋅s (P)

    Now, the mass of the Moon is 7.3477E+22 kg*, plus the mass of the two impactors at 3,232 kg (Meh… A drop in the ocean!), and the total momentum of both impactors is P / m = v

    ∴ 8,080,000 / 7.3477E+22 = 1.09966384E-16 m/s

    WTF does that mean in plain English? Well, it means that, as a result of both impacts, it will take 1,052,510,199 days (~2,881,565 years) for the Moon’s orbit to deviate by 1 cm.

    So, nothing to worry about! ūüėé

    *Source: Wikipedia — LCROSS; Moon.



    Now, the mass of the Moon is 7.3477E+22 kg, plus the mass of the two impactors at 3,232 kg, and the total momentum of both impactors is P / m = v

    That last bit should read: “… and the total momentum of both impactors is P; [so, if P / m = v]…”

  17. Colin

    What about the danger to “the clangers”

  18. Stinky Pete

    Isn’t anybody else concerned that this impact will erase President Nixon’s boot print from the surface of the moon? What about the birds on earth? They are the direct descendents of the dinosaurs. How will a man-made impact on the moon affect them? Unless this experiment solves the ages old ambiguity of boxers/briefs then I hardly think it is worth doing. Wise up america! Stop going to the real moon when all we have to do is build a life-size replica of the moon out of legos in a dergible hangar in Duluth. DUH!?!?!


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