Spelunking the lunar landscape

By Phil Plait | March 5, 2010 6:30 am

Need a little bit of jaw-droppiness today? Mwuahahaha. Let me show you something:
a hole in the Moon.


[Don't tell anyone, but that's where they faked the Moon landings!]

This is an image from the Lunar Reconnaissance Orbiter, one of my favorite spacecraft in existence. It’s been mapping the Moon at an incredible 50 cm/pixel resolution — that’s 19 inches, my pretties — for a while now, and revealing one astonishing thing after another.

lro_skylight_rilleWhat you’re seeing here is indeed a hole in the Moon: what is almost certainly a skylight, a hole punctured in the roof of a lava tube, an underground tunnel carved by flowing molten material on the Moon. The hole is about 65 meters across — roughly 2/3rd the length of a football field. This region of the Moon is called Marius Hills, and is known to be volcanic in nature. The clincher is that the hole sits in a rille, a sinuous, snaking gully in the lunar surface.

The picture on the left provides a little context. The hole is the very dark feature near the top, and sunlight is coming from the left. The rille is pretty obvious here, snaking more or less top to bottom, and the hole is smack dab in the middle of it. The place is littered with craters, most of which are soft looking, with no rims and very smooth features, which are possible indicators of very great age (erosion from solar wind, newer impacts, and thermal stress from the large day/night temperature swings wear down sharp features over time), or perhaps the regolith (the ground up rocks making a loose soil-like composite) is just very thick here, softening the sides of craters.

Let me show you another view, a bit closer in:


This section is about 1 km (3000 feet) across; in other words, it might take you about 10 minutes to walk across it (here on Earth, that is; in a spacesuit YMMV). The arrow at the bottom shows you the direction of sunlight; the Sun is coming from the left. That’s important, because our eyes get fooled easily if sunlight is coming from below; it makes craters look like domes and vice-versa. A lot of softer craters look like domes to my eye in this shot, so I marked a nice sharp crater with a 2 (the hole itself is labeled 1). See how the right side of the crater is bright? That makes sense if the Sun is on the left.

I marked the top of the rille with a 3, and the base of the sloping side with a 4. Think of it as the top and bottom of a riverbank. The other side of the rille is off the picture to the right.

OK, still with me? Now look at the hole again. The bright crescent around the hole on the right and the dark part on the left must be due to a slope leading into the hole, as if the whole thing is not just a hole punched into the surface, but more like a funnel pushed into it. The hole probably started out somewhat smaller, and the sides collapsed down a bit. Think of digging a hole in dry sand and you’ll get the picture.

This means there’s a lava tube under the rille, probably carved out by an older lava flow. Observations by the Japanese probe SELENE indicate the hole is about 90 meters deep, and the roof — the top part of the tube — is about 25 meters thick. That explains why it hasn’t collapsed under the eons of meteoric bombardment forming all the craters in it. The hole may be a collapsed section, or it may have been punched by a larger meteorite. Given the size of the hole, the impactor couldn’t have been bigger than a few meters across itself. Had it been much bigger, I’d think more of the roof would’ve collapsed.

Incredible! And useful, too: radiation from the solar wind may be a problem for future lunar colonists. A good solar flare could sicken or kill them, so they’ll need protection. Building underground is one way to do that, and here we have a pre-fab cave! It’s unfurnished, a bit of a fixer-upper, but ready for occupants, and priced to move.

You may think a colony on the Moon is fantasy, but I disagree. It’s a matter of realty. And of course, location location location.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures
MORE ABOUT: LRO, Moon, rille, skylight

Comments (85)

  1. chas, PE SE

    In Heinlien’s story, “Nothing ever happens on the Moon”, he has a couple of Lunar Boy Scouts getting caught in a feature like that.

  2. Jacob

    I thought you might want to take a look at today’s SMBC!


  3. Messier Tidy Upper

    Awesome! 8)

    YMMV = ???

    So this could be a future colony site? I hope so. I hope I live to see it. :-)

    Really minor nit to pick though here : SELENA is actually SELENE isn’t it?

    One of the lesser known spaceprobes that one – but still making a good contribution here. Omedeto (congratulations if I recall right) to them! :-)

  4. YMMV = Your Mileage May Vary

    And you are right, my eyes were totally fooled for a second and it looked like light was coming from the right.

  5. Messier Tidy Upper

    ^ Thanks for that Larian Le Quella. :-)

    my eyes were totally fooled for a second and it looked like light was coming from the right.

    Mine too.

    This region of the Moon is called Marius Hills, and is known to be volcanic in nature.

    Isn’t it all volcanic? Far as I remember there aren’t too many sedimentary or even metamorphic rocks on the Moon. ;-)

    BTW. Whereabouts is the Marius Hills region – which is the closest mare or major crater to it? Is it visible with a reasonable telescope?

  6. foolfodder

    Could we create our own cave systems in the following way?

    1. Find big crater.
    2. Build prefab tunnels.
    3. Launch a large number of small asteroids at the Moon to melt a bit of it near the crater.
    4. Blast out a river channel to channel the molten rock over the prefab tunnels.

  7. Greg

    Prolly full of Space Nazis. We’ll have to nuke the site to be sure.

    I like foolfodder’s idea.

  8. Cheyenne

    “…radiation from the solar wind may be a problem for future lunar colonists.”

    “may be…”? Or more like “duh, OF COURSE it will be”? Not to mention cosmic rays as well. ALTEA is one experiment you might want to look into. If you sit a human on the moon for a couple of months you’re going to turn that person into a mental vegetable – with cancer. Unless, of course, you just stuff them down into some Dr. Evil space cavern for the entire time. But what would be the point of that? And no, there are no magic shield space suits that magically stop radiation.

    “High doses in short periods, like what can be experienced during a solar storm, can cause acute radiation sickness, leading to organ failure or even death.” (quote from NASA). I’d just suggest that people that are really gung ho with the urge to launch human bodies at the moon or Mars study what NASA has been discovering recently about the radiation dangers that space travel will have on the human body. Quite obviously, some of the results of radiation testing was a contributing factor to killing Constellation.

    Seems like we’re getting on pretty good with LRO and its friends. Let’s focus on those missions.

  9. Pi-needles

    Wait on .. Could that be the lair of the mighty Moon worm famously ridden by Al Gore? ;-)

    (Futurama ref for those who don’t already know.)

    Think of digging a hole in dry sand

    Don’t you mean digging a hole in green cheese – that’s what the Moon’s really made of after all isn’t it? ;-)

  10. Cheyenne, along with learning about the radiation, we also are learning how to mitigate it aside from just piling dirt on top of an outpost. Since the particles have charges, and energy would be rather plentiful in the form of solar during the highest risk times, an electromagnetic field can do wonders.

    Here is a neat quick look article: http://www.space.com/businesstechnology/lunarshield_techwed_050112.html

  11. Gus Snarp

    On a completely different topic, have you seen today’s SMBC comic: http://www.smbc-comics.com/#comic

  12. alfaniner

    I found that just by tilting my head to the right a bit, the perceived domes snap into pits. An interesting psychological phenomenon!

  13. MoonShark

    Heheh, I was gonna make a moon worm comment too. Damn internet, the whole place is full of Groening references ;)

    FWIW I don’t get the dome illusion at all here. I’ve only gotten it a couple times, ever. But here especially I have to try to make myself see them. Guess I’m wired differently?

  14. cuggy

    Hey Phil did you notice you’re given a name drop in today’s SMBC?

  15. Kimpatsu

    A hole in the Moon? That’s a lunar cavity, right? So where’s the dentist? Galactus?

  16. bouch

    Once I read the text a few times, the direction of the sunlight made sense. To me, the arrow pointing to the right mean that that was the direction the sunlight was coming FROM, and that got me totally confused.

    Phil, might I suggest that you redo that graphic with the arrow pointing left, and the title saying “SUN” instead of sunlight?

  17. Phil. Do you not realize that by telling me there was once lava on the moon, I will now scour the Internet for more information about that? IF I WAS A CAT, THIS SITE WOULD BE KILLING ME.

  18. dumb guy

    While I believe y’all, I’m just not convinced that the sun is at the left.

    Are there no domes in this photo?

    And the contrast between the hole and the other dips is great. Wouldn’t they have the same brightness? I suppose the angle of the land could give a different reflection.

    one seriously dumb guy

  19. rob

    the Heinlein reference is almost right. it is actually an entrance to the arachnid moon base.

  20. Cheyenne

    Larian – Thanks for the link and I know research is ongoing. I did read that article but I don’t think it really helps the case for sending humans to the moon in any way.

    “The researchers are currently not addressing the shield design’s power needs, though scientists with past studies say they may be staggering.

    “The real issue is what type of power levels will this type of shield need,” said NASA physicist Robert Youngquist, who is studying the potential of an electrostatic shield for future spacecraft. “If it’s too much current, that’s a potential showstopper.”

    Respectfully, I think your article causes even more concerns.

  21. Gus Snarp

    @dumb guy (and others pondering the optical effects of the sun’s position) If you click on the first image it actually links to another image that is reversed so the light is coming from the right. You should then easily see what the surface actually looks like, with all the craters looking like craters instead of domes.

  22. Elidor

    Martin Landau and Barbara Bain nod approvingly.

  23. Cheyenne

    @Larian – Not to be too much of a blog troll but that article you highlighted linked to a number of other articles that are rather downers on the whole “extended mission to moon” plans.

    “We can certainly expect that space travel will lead to risks to the central nervous system, said Charles Limoli, a radiation oncologist researcher at the University of California San Francisco who was not related to Josephs study. And those effects are progressive, presently untreatable and poorly understood.”

    There’s about 5 other articles on Space.com concering radiation hazards that I could quote mine from but I won’t. NASA doesn’t have a solution to the problem, and it shouldn’t waste billions of dollars and man hours on human moon plans until it has a better idea of how to solve that problem (and all the others).

  24. Grizzly

    In some respects using a “pre-fab” cavern like this one would bring its own problems. How do you assess the structural integrity of the caven as a result of previous impacts? How do you shore it up if it needs it and/or repair structural flaws?

    This isn’t the great big lava dome of Heinlein’s Menace From Earth… although gee, that image is something that I’m sure more than a few of us remember with fondness. I mean, who wouldn’t want to be able to fly?

  25. bb

    Em, Dr. Plait,

    have you really been mean to the military?

  26. Oh, I totally understand Cheyenne. It IS a very new area of research and consideration after all. Keep in mind, before we set down on the moon back in the ’60s, there were serious doubts about many things that would have made the trip a one way death wish. Just saying that an obstacle doesn’t make the entire endeavor invalid or a lost cause. :)

  27. Cogfizzle

    I’m shocked and disappointed that nobody has made a “shoot the moon” gag yet.

    That is all.

  28. Now let’s see…

    The massage cavern will go right around #4, and the lunarium will be closer to #3. The dance hall will be right in the middle, between the food court and the swimming pool. And at 90 meters the hole would make a swell atrium just off the entrance foyer.

    Yup. Kuhnigget’s Lunar Spa would fit quite nicely.

  29. Nah…the hole’s how they inflate the moon.

  30. Stubby

    I thought it was obvious that the moon has holes in it. Its made out of Swiss cheese after all…

  31. Honest newbie question: if the sunlight is coming from the left, why are the shadows on the left? Can someone explain? Thanks!

  32. My 2004 BIS presentation and 2005 JBIS article about Lunar exploration, including a discussion about building a colony in a lava tube, and bibliography


  33. Mike C.

    Looks suspiciously like a grassy knoll, only without the grass and the knoll.

  34. @kaelinn18. What you’re seeing are dimples not domes. Or craters if you want to be more correct and less alliterative.

    Personally I had to tilt my head way to the right to see the images with the right polarity.

  35. BigBob

    I often fall victim to the mud pie / dome illusion from images of craters. It doesn’t help that there’s a big bright window to the outside world to the right of my desk. So the Bob brain always assumes the picture is lit from the right, even when told it’s the left. Easy solution – I just copied the big image with the numbers, pasted it into my graphics app, and got it to rotate the image 180. Result – instant craters!

  36. Oh, I see now. Thanks, guys!

  37. kev

    Mysterious holes in the ground make me think of X-Files.

    But at 2/3 the length of a football field, that’s a pretty cozy colony. Unless it comes with tunnels underneath as you say, then it would probably be a pretty nice size.

    But if I was a kid living in a lava tube, I’d always be having nightmares about what if the lava starts flowing again!

  38. James

    Because they are crators… The light comes into the hole at an angle. There is nothing in it’s way so it lights up the right hand side. If these were hills it would be the other way round.

  39. rumleech

    It’s where the Clangers (look it up) live. Or the Soup Dragon.

  40. Wow! An ordinal fraction!

  41. Joe Meils

    Caves on the moon? What a fantastical idea! Why… no one’s considered THAT before!


  42. Bramblyspam

    I’m not at all convinced that we’ll see a lunar colony within our lifetimes. The bottom line is, well, the bottom line – shipping stuff to orbit is hideously expensive, shipping it to the moon is doubly so. I don’t see a moon base making economic sense for a very long time. It does make some scientific sense, but I don’t see what science a lunar colony can do that robots couldn’t do far more cheaply, not to mention safely. Further, our robot tech seems to be advancing far more rapidly than launch costs are going down.

    I remember decades ago hearing about future manufacturing facilities in space, for perfectly round ball bearings and crap like that. We still don’t have anything of the sort. Satellites in earth orbit make plenty of economic sense, but only for telecom, weather, and other such applications where you aren’t physically transporting stuff back and forth. Those kinds of applications are better & cheaper done from earth orbit than from the moon.

    I don’t expect us to see a lunar colony until launch costs shrink to a tiny fraction of current levels. Suppose you get costs down to a million dollars for transporting a space shuttle-sized cargo to the moon and back… even at that cost level, what could you do on the moon that would make a space colony make economic sense? I can’t think of any application, aside from perhaps catering to super-rich tourists.

    Just about everything we can do on the moon, we can do better & more cheaply on earth. I’d love to see launch costs reduced to the point where a lunar colony makes sense, but we have a long way to go for that. Yes, I’ve heard all about space elevators and the like, but I heard all that talk decades ago, and still don’t see it turning into reality.

    Need I mention that massive projects always run into unforeseen complications? I don’t suppose I’m the only one who recalls that the space shuttled was billed as a cheap launch vehicle that would get costs down to $5 million per launch.

    Anyway, pardon the derailing. Cool lava tubes!

  43. Cheyenne

    “You may think a colony on the Moon is fantasy, but I disagree. It’s a matter of realty.”

    Wrong. Wrong cubed. Paris Hilton level wrong.

    We keep thinking like this and we make awful policy decisions that have real consequences. Constellation/Ares was a stupid program from the get and a lot of us were trying to point that out. Now we’re out $12-13 billion with nothing to show for it (well, “we” doesn’t include the defense contractors that made out hugely). That’s real money that could have been spent on actual science and exploration.

    Sorry Phil but we need more “reality based thinking” here.

  44. @Bramblyspam (42)

    > even at that cost level, what could you do on the moon

    If you compute the delta-v’s, you will see that a Moon base with local oxygen-extraction facilities would open up the whole Solar system to research, mining, tourism and everything else really

  45. That’s a really good explanation.

  46. I don’t know if this will work for other folks, but whenever there’s one of these images where it’s hard to make your eyes see craters instead of domes, I download the image and rotate it in Photoshop until the sun is apparently coming from the top. Then it all sort of clicks into place. Suddenly they look like craters and holes instead of a confusing texture.

  47. @Cheyenne – read that last word of your quote again. Hint: it’s a pun.

  48. Levi in NY

    No matter how hard I try, my brain won’t let me “see” the sunlight as coming from the left. I know those are all craters there, but dammit, they look like domes to me.

  49. !astralProjectile

    Agreeing it won’t make economic sense for centuries. 3He might be useful for high efficiency power supplies for space drives (because you can get electrical energy directly from the proton), but I doubt it will ever be much used on Earth.

  50. amphiox

    @Cheyenne – so it’s going to be hard. Doesn’t mean it’s not worth doing, or impossible to do.

    Since we already know how to shield against radiation here on earth, we know there’s no scientific or technological barrier that says it is impossible.

    However much (or not much) advances in technology might shorten the time, reduce the risk, or decrease the cost, the fact is we can already do it, today, using current technology. We could ferry up all the necessary building material with unmanned missions (1kg, 2kg, or whatever the lift capacity turns out to be, at a time). Then send robotic missions to start building whatever our robots can handle (however many missions it takes). Then send up humans on short Apollo style missions to complete the building (a couple hours, a couple days, however long we can manage safely, at a time). We build all the infrastructure and all the shielded vehicles necessary for the outdoors work, and then we send up the colonist, 1, 2, 3 or 4 at a time, however many trips it takes.

    It would of course take many, many times our currently yearly GDP, and maybe several centuries or more to get it done this way – but the point is that it is technically possible. There are no fundamental showstoppers here.

    It’s not a question of technology or science, but a question of economics and will. The will to take the time, pay the cost, and accept the risk of deaths and injury.

  51. Mike C.

    Joe Meils — Thanks for posting the link to the trailer of my all-time favorite Lionel Jeffries flick. May that delightful actor, who passed away just recently, rest in eternal slumber, hopefully someplace that has plenty of oxygen, sunny beaches and lots of well-written parts for wonderfully eccentric character actors.

  52. Wayne Robinson

    “I’m not at all convinced that we’ll see a lunar colony within our lifetimes. The bottom line is, well, the bottom line – shipping stuff to orbit is hideously expensive, shipping it to the moon is doubly so. I don’t see a moon base making economic sense for a very long time”.

    Gives me an excuse to mention Frank Schaetzing’s science fiction novel “Limit” published last year. Set in 2025, it has the space elevator (which would make it cheap to get mass into geostationary orbit) and a lunar base at the North Pole mining the lunar regolith for helium-3. In the novel, the astronauts solved the radiation problem by mostly staying underground and restricting their exposure to less than a total of 1 or 2 weeks above ground in a 6 month rotation. Lava tubes also were included in the story.

    Helium-3 (for nuclear fusion) is perhaps the only reason why humans are desperate to return to the Moon. The possibility of getting a new cheap non-polluting energy source makes economic sense.

  53. All together now…

    “Too Far! Too Soon! You saw the hole in the Moon!….”

  54. Jeffersonian

    I don’t get this one. Is it:
    *The exit hole of a worm tube (and the entrance is off-pic)
    *There’s a natural arch in the rim of the crater

  55. locke

    Thanks Cheyenne and Bramblyspam for a dose of much needed reality on the idea of lunar colonies. and @45, I think you’ll find that NEOs make much more economic targets than the surface of the moon, not to mention the better science returns such as determining their structure so we’ll know better how to deflect them, if need be.
    @53 Talking about He-3 reactors reminds me of the joke about the plasma physics community: “just wait 10 more years, and we’ll have working fusion…. ” and they started saying that 40 years ago or so. It’s much more likely we’ll have solved our renewable energy problems LONG before we have any kind of economically sensible fusion reactors.
    Check out http://depletedcranium.com/helium-3-from-the-moon-dumbest-idea ever for some good basic science on He-3 fusion (it’s a little out of date, as we do have a serious He-3 shortage now, but that’s easily fixed if it was REALLY important)

  56. jjmcgaffey

    Nope, they are all very determinedly domes to me – I even tried the inverted version on the clickthrough and it looks the same. Ah well. I believe you, really I do.

    Wow, a hole in the Moon! Neat. I’ve seen lava-tube sinkholes on Earth (though generally tubes with much thinner roofs), but it’s not something I would have thought of as being on the Moon.

  57. I wonder how much air pressure that cavity could retain if it was sealed adequately?

  58. Magnum

    This confirms that the moon is indeed hollow.

  59. JB of Brisbane

    Rather than Heinlein, I was thinking more of “The Lotus Caves” by John Christopher… only those caves were self-sealing.

  60. Gary Ansorge

    25. Grizzly Says:

    ” How do you shore it up if it needs it and/or repair structural flaws?”

    I expect we’d just put inflatable domes inside the tubes. As far as shoring up the tube walls/ceiling, a solar refractory mirror could be used to melt lunar dust, shape it in molds into structural components and use those to stabilize the tunnels. On Earth, we’d probably use concrete but that’s not a likely solution on Luna.

    Electrostatic field effects would act to DEFLECT charged particle radiation, since the incident energy of solar particles and cosmic rays is on the order of billions of electron volts, a true “shield” would have to be hideously powerful(billion volts or so). But we only need to shift those particles to one side, not stop them cold, so a few million volts electric field should do the job of deflection.

    It’s been pointed out by others that only 3 meters of lunar dust could provide adequate radiation shielding. Which is one solution but if you’re adverse to living under dust, the magnetic/electric field solution seems to be a workable one. I just prefer simple solutions to these problems, so living inside a lava tube strikes my fancy(Occams Razor). It’s a pretty elegant solution.

    If we ever get serious about using nuclear power (See: nuclear light bulb), we would also have the exact device to drill holes in a crater rim for habitation(an exhaust temp of 20,000Kelvins would male a great plasma cutter). Just point your fission rocket exhaust at the rim and presto,,,tunnels with their walls melted into a strong, non-porous material.

    The first settlers of the new world came here on foot and by small boats. The next wave came in state supported ships. The first time anyone landed on the moon, it was a national effort by the richest nation on earth(at the time, we controlled 60 % of the worlds resources).

    THAT was for exploration. To develop lunar resources, make them into solar power satellites and other goddies, will likely require the productive capacity of the entire planet.

    Big projects require big cooperation.

    GAry 7

  61. amphiox

    @56 – I agree about the NEOs. In fact I think we should be considering manned missions to at least some of them even before we think about sending people to mars.

    @62 – It is important to note that the historical analogies indicate that big centralized efforts may be necessary for exploration, and for the establishment of colonies, but beyond this first step, the longterm success of the colonization effort is driven entirely by economic imperatives acting on private individuals and organizations. If the first explorers of the Americas had found just a ice strewn or volcano blasted wasteland with no edible animals or plants or drinkable water, no one (save for the occasional scientist on short term trips) would ever have come back.

    The medium and long term success of any space colony, lunar or otherwise, depends on becoming self-sufficient – completely independent from earth. If this does not happen, sooner or later, the colony will fail.

  62. Gary Ansorge

    63. amphiox

    Granted, economic(read as: recovery of essential resources) is the final imperative for large scale development/colonization. If the original explorers to the new world had found gold(and nothing else), I’d expect some entrepreneur would have developed it and that takes man power in situ. The closest parallel we have is the rush to develop arctic resources(no people, no food,everything for human support has to be transported in, except air and water). Or another weak parallel was the development of Saudi oil resources, which was very difficult(vast deserts, little water, etc). Just because something is difficult doesn’t mean it’s impossible. Lunar resources fall in the same category:hard to access but potentially profitable. Just a few more problems to work around.

    GAry 7

  63. Keith

    “Building underground is one way to do that, and here we have a pre-fab cave! It’s unfurnished, a bit of a fixer-upper, but ready for occupants, and priced to move.”

    Phil, you’d be a great real estate broker. :)

  64. steven

    what a load of pish the sun is clearly shining from the right

  65. amphiox

    Just because something is difficult doesn’t mean it’s impossible. Lunar resources fall in the same category:hard to access but potentially profitable. Just a few more problems to work around.

    No argument with you there on the overall principle. But I’m not quite as convinced yet that lunar resources, even with the water the helium-3, have enough economic potential to justify a large scale habitation in the near future. I’m leaning more towards the likelihood that as we colonize space, we’ll bypass the moon for greener pastures – Mars, NEOs, etc.

    There’s also the possibility of a smaller scale occupation of the moon for research/military purposes, of course, or as a waystation for longer journeys (but in these situations the likelihood is that the lunar facility won’t be established first – it’ll come later, after more distant but more profitable colonies have already been set up).

  66. Asimov Fan

    @ 61. JB of Brisbane Says:

    Rather than Heinlein, I was thinking more of “The Lotus Caves” by John Christopher… only those caves were self-sealing.

    Ah yes. I remember really enjoying that novel as a young kid too. Good memory & reference there JB, thanks. :-)

  67. Steve Russell

    D’oh!…. The sunlight is coming from the right, Phil…. all the shadows are on the left.

    Talk about bad astronomy!!

    If you got this most basic and obvious observation wrong, doesn’t that call into question the accuracy of your entire thesis?

    Most definitely NOT awesome.

  68. Steve Russel (70): I showed just why I know the sunlight is coming from the left in the images I have here. Why don’t you show your reasoning?

  69. Gary Ansorge


    Some people can’t tell the difference between a hole in the ground and a mountain,,,maybe he’s a mathematician.

    67. amphiox

    I seriously doubt we’ll have He3 fusion before we have Boron11 + Proton fusion(Bushards preferred fusion cycle). ,,,and Boron11 is a whole lot more available than He3.

    There has been at least one scientist pushing for building solar power generating facilities on the moon and transmitting the power to earth. Presumably because he believes it easier to build such devices under 1/6 G than in free fall. Personally, with Tele operated robots doing the “outside” work in space, I see little to dissuade us from building these mega engineering projects. I expect it will require national commitment on a global scale to really make these projects possible. We only need to show ONE likely profitable return on the investment and solar power sats are one such. Once the infrastructure is in place to build these devices, there will be many other profit making ventures that can piggy back on the initiating venture(Power Sats).

    ,,,or we could just build dams across the Straits of Hormuz and Gibraltar. Both the Persian Gulf and the Mediterranean lose more water from evaporation than is replenished from fresh water flow into these water bodies, so a power generating dam across these sites would allow the water levels to fall and provide the hydraulic drive for these dams. Of course, the millions of people who live around these seas would probably object to losing their shore property but,,,hey, it’s all about (electric) power (to the peeples). Of course, those dams wouldn’t do US much good. They would probably cost just as much as building the infrastructure to create power sats.

    GAry 7

  70. Scott de B.

    “I don’t expect us to see a lunar colony until launch costs shrink to a tiny fraction of current levels. Suppose you get costs down to a million dollars for transporting a space shuttle-sized cargo to the moon and back… even at that cost level, what could you do on the moon that would make a space colony make economic sense? I can’t think of any application, aside from perhaps catering to super-rich tourists.”

    This issue has been discussed since before the first Moon landing. Von Braun pointed out that if you want the cost of some activity to come down, the way to do that is not to sit around hoping for some serendipitous technological solution, but rather to do the activity over and over again. That’s why he wanted Apollo to produce a lasting infrastructure for space travel.

    Yes, sending three men to the Moon was/is hideously expensive. But you do it, and the second time, it’s a little cheaper, since you’ve done it before. Third time is cheaper yet. Commit to a program of sending three men to the Moon every year for the next 50 years, then you can get private companies to compete for the contracts for rockets, space capsules, etc. etc. If we say we’re sending one rocket to the Moon, that’s one thing. Say we’re sending 50 rockets, then the contract to produce those rockets becomes very attractive for companies. Get companies competing against one another for multi-billion dollar contracts, then you’ll get your innovation and your lower costs.

  71. Eric

    Great windows gadget about moon phases http://lunarphasegadget.codeplex.com/

  72. amphiox

    @72 – I share your reservations about He3 fusion. Actually, I’m pretty skeptical about any form of fusion requiring exotic isotypes as a sustainably longterm energy solution. I don’t think anything other than straight out H fusion is going to be viable, and we’re probably a long way off from that.

    Space-based solar power sounds intriguing, and probably has a pretty good chance for being the first big enabling space-based resource that will drive future colonization, but I’m betting that space-based orbital zero-g installations will win out over installations built at the bottom of any pre-existing gravity well, lunar or otherwise.

    @73 – But there’s got to be some compelling reason to motivate building those 50 rockets in the first place. The water, and any other resource for use in situ, is enabling, but alone it isn’t enough, unless you’re talking about exporting that water back to earth, and if it comes to that (a water shortage on earth necessitating the contemplation of importing more from space), I think we’ll be having bigger problems to be worrying about!

    Another possibility is the export of that lunar water to other space based installations, orbital outposts, NEO outposts, etc. But those are situations where the lunar base can’t be our first step off earth. It will only become economical after some other extraterrestrial outpost is established.

    I really think that the likelihood is that the moon will never be a primary destination for space colonization, but instead will at most serve as a waystation/resource source for other, more promising locations.

    (It does remain quite possible that despite such reservations, we will still go ahead and build a lunar colony, which will last several decades, never achieve self-sufficiency, and ultimately fail, possibly because an economic downturn results in earth-based support drying up, BUT that during its period of operation, it will serve as a support hub enabling colonization of other targets further out in the solar system. Then several centuries later, archeologists will come back to dig up the buried ruins of the old lunar colony, ala Jamestown and Vinland, and speculate as to the proximate causes of its failure.

    If this does happen, I suppose with hindsight we can say that the lunar colony succeeded, after all.)

  73. Nikolai

    The dome instead of crater problem is a kind of optical illusion that is common with photographs that are oriented differently than the viewers eye is used to interpreting. I worked as an imagery analyst for a while and found that the easiest way overcome this optical problem is simply to rotate the image.

  74. Cheyenne

    @jtradke – Thanks chief. I do understand how Phil’s puns work. He’s very (very!) good at them and gets at least 2-3 in on the average article he posts.

    But if you are a long time reader of this blog you would know that he has commented/posted/whatever you call it tons and tons of times about his support for a long term presence on the moon and support for the ISS (he may critique it, but only mildly, still supporting us shoveling money into it). He may be right 80% of the time but sorry, on these issues, epic fail. Hurt science kind of fail.

  75. Cheyenne

    @Amphiox – “It would of course take many, many times our currently yearly GDP, and maybe several centuries or more to get it done this way – but the point is that it is technically possible.”

    I completely agree with you…

  76. Gary Ansorge

    75. amphiox:

    You might want to check out this presentation to Google on what appears to be a very viable approach to reducing base launch costs by 95%.


    GAry 7

  77. Donovan

    Yeah, yeah, yeah… You expect us to take the far out notion that some mysterious rock zooming through space hit the moon, punched a hole into a gigantic cave, and vaporized so it leaves no trace, ie no proof? Extraordinary claims, Phil, need extraordinary publicity.

    Look, this hole was to be expected, predicted even, by FSM theology. FSM made the moon, set it upon its axis, and made it spin around and around. The problem was that the spin was wobbly and out of sync with the lunar orbit of the earth. This made the light side and dark side of the moon flash erratically all night long and nearly made humans go extinct from epilepsy. So FSM placed the axis in a more balanced diameter and attached it to the gears that make it stay in sync with it orbit around earth.

    This is basic mythistory, Phil! That hole is where the old axis was.

  78. karen massey

    how is it that i’m surrounded here by a bunch of brilliant bloggers and no one else notices a crucial part of evidence is missing? the damned hole has no solidified lava flow, no eruption patterns. i feel like i’m being bamboozled into believing a diversion hypothesis.

  79. Clive Baker

    While people saying the c0st is going to be a prohibitive…

    Once manufacturing/launch systems are in place on the moon, the costs drop enormously. You no longer have to bring large supplies from Earth, only people. Fuel, systems for escaping Earth’s atmosphere aren’t needed when launching from the moon. You have no(minimal) atmosphere, minimal gravity, etc. Now all that weight in fuel and the lift package can actually go to research equipment, and supplies. Getting materials from space to Earth isn’t nearly as costly as launching them from Earth to space.

    That is why getting a base/colony on the moon is so important to future space exploration.

    But we do have to go back to the cost to get to that point which your points stand, is a large amount and prohibitive.

  80. Fry

    Your NAC image is transposed.


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