Originally published at: https://boingboing.net/2015/05/22/the-man-who-sold-the-moon.html
Makers and hackers develop a robot that creates building materials from sand, and set out to send their 3D-printing marvel to the moon. In the way of their dreams? Code, crowdfunding and cancer.
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The āNomen Luniā link (which should probably be āNomen Ludiā) under the āMore Fictionā heading below the story is broken. (Probably should be http://boingboing.net/features/nomenludi.html )
P.S. Cory, thanks for making your story freely available!
The moon dust will be THE BITCH for any moving parts. Imagine glass grit, with sharp edges and friable, eating through metal like sandpaper and with so variable particle sizes that the bearing seals will have to be equipped with a good luck charm.
Vacuum. Lubrication will become another issue; liquid things will outgas, solid ones often stop working; graphite needs water and air molecules between the layers to work, outgas those and bye bye lubricity. Bare metals cold-weld together, in absence of oxygen to replenish the oxide layers. MoS2 and WS2 do not have such issues, though, so they can do the job if sputtered or otherwise deposited on the parts. But then you get the moon dust to abrade them away. Maybe a metal-matrix composite, or a metal dust sintered together with the solid lubricant particles to retain low friction through the mass as it wears off? Inaccuracy-tolerant design for moving parts, so the wear and increasing play wonāt lead into parts seizing? Magnetic or perhaps even superconductive bearings, so there is actual significant spacing that can be dust-contaminated without adverse effects?
Then there are the temperature swings. MAJOR ones, as the Moon spins; maintaining temperature of the crucial components will be critical. Old Russian probes used radioisotope heaters; Iād be in favor of those as well, maybe even a full-scale small reactor, Russians also had those. The lunar nights are annoyingly long; there is a chance a phase-change material packed through the structure, or perhaps embedded in the construction materials themselves as a filler in another metal-matrix composite, may work for enough time but that may add a lot of mass and make it too expensive. Or the thing can be designed to build its own igloo, or bury into a hole.
Thought. The phase-change material in question could be water. The Gadget may be using that old-now NASA trick of extracting metals and oxygen from the lunar regolith; electrolyze water, use hydrogen for reduction of the oxides, take away the oxygen, reclaim water from the hydrogen and the regolithās oxygen, and salvage the metals. May be an alternative to the ceramics sintering. During lunar days, the thing can operate using sunlight; during nights, all the hydrogen in the machine can be reacted to water and used as a PCM. Or, perhaps better, use both oxygen and hydrogen as energy storage for fuel cells or for catalytic burners to maintain temperature. Stop work when things get too hot or too cold, to prevent seizing or excessive wear on bearings and sliders when the thermal expansion may change their dimensions off limits. Monitor actuator currents and vibrations to have feedback about wear.
Another thought. The Freelunchās design apparently sucked. No redundant systems, no redundant telemetry (even a few milliwatts from a separate transmitter would do a decent job, if a big antenna gets hired on the ground and trained onto the Moon). Multiple solar arrays can have a separate power bus each, with independent hardware; one fails, others go, with lowered total power budget but maintained core mission capability (or at least telemetry to tell us what went wrong). Switches on key systems can be quadrupled - two pairs of parallel ones in series, so any of them can fail either open or closed without total failure; same goes for diodes or gas/liquid valves. Computers must be doubled or multipled. Radio systems must be doubled or multipled, with keepalive signals to keep them from switching between; if communication fails for too long, cycle to next radio (similar with computers); this way we can not accidentally switch to a failing radio and get stuck there, which happened to at least one satellite - if things seem dead, cycle through the redundant units until things go alive again, and liberally use keepalive mechanisms. Pepper the state machines with failsafe behaviors, held in check with keepalives, so the SM wonāt get stuck if anything breaks. Have backups of backups of backups, and then backups of those. And you can have it with low weight, with todayās electronics; you cannot use big chip packages anyway because of differential thermal expansion, so brazing onto CTE-matched copper-tungsten composite heatsink it is, and you can get quite some bare chips there that way. Look at a common FET transistor - peel away all the metal and plastic and you end up with a thin sliver of silicon, or more rarely silicon carbide or gallium nitride or other exotics, with negligible weight and almost negligible size, even for the power ones. In comparison with launch cost, thick-layer hybrid circuits are cheap - I think I inherited some samples made in 80ās or even earlier, saw them under a microscope when I was a kid, and you can buy the wire-bonding gold wire on ebay these days. You can buy the whole fucking wirebonding station, and thatās pretty much all you need for such circuitry; brazing chips to the substrate is an elementary school level material engineering with matching the wetting and CTE characteristics of the substrates and the filler metal, go for germanium-gold alloy in a thin layer for the beginning, itās commonly used, or do a literature research (todoā¦) for a better one.
Thermal management WILL be a royal bitch. In vacuum, nobody convects away the heat, itās conduct off or radiate away. Thought: use a Stirling cycle cooler, with controlled displacer; by controlling the phase of the displacer you can select which end is hot and which end is cold. Have one end on a radiator array, the other one in the middle of the machine, with heat pipes snaking to all parts that need their temperature to be maintained. Heat pipes have no moving parts, Stirlings have just a few and are space-proven by now.
Vacuum and low-g operations are tricky, but there is a large body of literature all over the bittorrents and obscure russian servers.
Gods, I want off this stupid rockā¦!
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Heat pipes can be useful in such an environment.
Also, it might be a useful strategy to blow a little sacrificial gas through the bearings. Sure it will be lost to the vacuum, but it can keep the surfaces bathed to a few torr. That might be enough to mitigate the sticktion/vacuum-welding problem. Use oxygen from extraction of metals from the regolithā¦
Down here, we have the advantage of minerals purified in geothermal springs over eons. Pure quartz crystals in nice large sizes. As far as we know no such process has happened on the moon.
If some of those big lava tubes can actually be found, that would help a lot. . .
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I like this!
On the other hand, this makes the precursors more homogeneous, less variable, more predictable.
Fourth of Juplaya
I didnāt know that was a āthingā. Thanks for this tale, Cory. I must look up more of your work. I confess to not having read any of it up til now.
Sounds like fun, but then I started to wonder, how long until the Blackrock Desert is permanently inhabited? Nah, I guess notā¦
Okay, bear with me here. Could you potentially heat moon rock/dust so that it off gases something that has thermal properties, buy not kick up the corrosive kernals? Basically so you could off gas from native material, and use that gas as a medium for heat exchange?
Or would it be simpler to build just heat exchangers with hydrocarbons from earth!
Ooh, what about harvesting gas from a hydrogen bomb set off on the moon, and use that in exchangers? Giant balloons sucking up gas from a sub terrianian hydro bomb would beā¦ Erā¦ The bomb.
Youāre welcome. Artistic license. Or whatever the most unrestrictive one isā¦
if some trolley wants to patent it, this Boingboing thread can be prior art.
The Moon is pretty much sunbaked. More than traces of gas are unlikely to be there. No carbonates to speak about too. Traces of trapped helium, maybe.
Youāre more likely to find water there, in the craters in polar areas. That will be massively useful. You can also bring your own, slam a comet to the Moon and harvest what remained.
And you can make mooncrete.
More about lunar mineralogy, something I stumbled over, about the lunar meteorites that can be found on Earth. You can even buy little pieces of some.
http://meteorites.wustl.edu/lunar/howdoweknow.htm
Go for Stirling engine heater/cooler, and suitable energy storage. Or a reactor. May be easier.
Wouldnāt it be a sublunar bomb? [nitpick]
At the poles, this could actually be a viable way to extract water!
Look at the attempts to get natural gas from ground using small nukes, e.g. the Gasbuggy nuclear fracking, from the Operation Plowshare. Not only fracture the rock, but also volatilize the ice present so it can be easily extracted.
Dangit! Donāt type and Newcastle Brown Ale at the same time!
Letās do it. I wanna Tsar Bomba the lunar poles so. Bad. Right. Now!
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Suddenly changed my mind about the āgreen moonā enviro movement. Maybe not so crazy after all 
Underground (okay, undermoon) detonation could benefit from more smaller charges.
Surface or above-surface will be rather underwhelming anyway. The beautiful fireballs and boiling, rolling smoke of the mushrooms are dependent on atmosphere; the xray flash that most of the energy goes into has to be absorbed and converted to thermal energy. Omit this, and all you get is bright photoflash. And maybe, if you were low enough, a circle of glowing molten lunar glass. Mechanical effects wonāt be anything great, even a bog-standard meteorite strike would look way better.
Cāmon, letās have some fun, and let the meek inherit this stupid rock!
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You have convinced me. Letās comet the hell out of this lazy, no good satellite. takes off shoe and pounds desk Moon! You are out of order, and your behavior Shall Not Stand!
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Good old shoebang, that always works!
Personally I prefer a little stronger statement here.
[throws the shoe at the Moon]
How has the name of this work been allowed. The 1st novella named āThe Man Who Sold the Moonā by Robert A. Heinlein was published in 1951. I only write this as a Heinlein fan who expected something different when clicking on a link.
Iād call it ānamespace collisionā. Pretty common with person names, less so but still quite common with works of literature.
Same as how your screen name comes right out of Jules Verne. Itās pretty tame as click-bait and so what if you lost a second or two figuring it out?
Great story, Cory! Thanks for making it available free. Now Iām much more likely to pay to read your other stuff.
My chief criticism is itās unlikely 3D printing would not change greatly in the taleās 30-odd year timeframe, or that someone else would have made it back to the moon in the interim. Then again itās been almost 40-odd since the last footprints there, and surprisingly few probes/landers either. Thatās a real challenge to deal with and keep the story tight.
Maybe Elon will bring the Heinlein story to reality?
Nuking it just seems so ā¦ pointless. Crashing comets into it, and youāre bringing nitrogen, an element sorely lacking right now.
Also, I could go for a program to strike its same limb repeatedly, to spin it up, for a ~24 hour lunar day. Now that would be useful āenvironmental damageā, heh heh.
Verne? Where from?
True that, to a degree. But that requires somebody actually wanting to. If there is no commercial interest, the corporations wonāt do much. The 3d printing may as well stagnate, or just the field of moon regolith sintering may not go anywhere fast. Or it may develop, but the developments donāt have to be significant enough to project into the story.
Hopefullyā¦
It gets the water from the deeper layer of the crust out, neatly, with a single drilled hole and one physics package. Iād keep it in the portfolio of methods.
Nitrogen, hydrogenā¦ would be handy.
Also, the heavier asteroids; theyād bring nickel, iron, platinum metalsā¦ useful engineering stuff. Smash a couple into the Moon and build up ore beds for later mining.
The momentum to add could be pretty formidable. (Anybody willing to assume a spherical cow and calculate the ballpark number of asteroids needed?)
It is also fairly useful to have the same face towards Earth. Helps quite a lot with maintenance of radio connectivity without having to bother with relay satellites.
Probably worth mentioning here is that the sintered anhydrite bricks of the story would be pretty fragile, and return to dust fairly quickly. Might be able to clean up by rolling over the igloo with a truck a few times. Anhydrite is soft and crunchy.
If the dust has just a little silica in it, it could be somewhat more durableā¦
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