
"figure out what would be necessary for a railroad network on the Moon"
Step 1 : eliminate the incredibly abrasive influence of Moon regolith on railroad tracks.
We'll continue when you've solved that.
All aboard the space train – DARPA has commissioned defense contractor Northrop Grumman to figure out what would be necessary for a railroad network on the Moon. Northrop Grumman announced that DARPA selected it yesterday, describing the defense agency's vision for a Moon train as one that could transport humans, supplies, and …
The expansion/contraction between the two weeks of night and two weeks of day would be massive, that may be an even bigger issue than the abrasion (since it is safe to assume the railroad would not be particularly busy anytime soon after it is built)
You're all assuming this would run on the surface, which is a mistake, becasue of Solar storms.
Nasa already started thinking about this in the 80s, see the frankly wild proposal for a nuclear powered TBM in this fascinating document about lunar materials, that creates titanium-glass coated tunnels for habitats and or infrastructure.
https://www.lpi.usra.edu/publications/books/lunar_bases/LSBchapter07.pdf
Then the dust will stick to the brushes.
Moon dust is highly charged - positive during the day when solar radiation knocks out its electrons, and negative at night due to electron bombardment from the solar wind. A small charge on the track might be enough to keep the dust off it. Just have to change the charge depending on whether it is day or night, and I suppose not run any trains during sunrise/sunset when the charge is changing?
Wheels similar to those of the Rovers of old, but more of them. A "road train", with (ceramic?) bearings in the axle housings behind a seal or seals to maintain the housings at a positive pressure, thus keeping the dust out It wouldn't take very much pressure at all, and use whatever gas is (relatively) plentiful. Removes the need for any kind of rail system, and allows easy re-routing as necessary. Running overhead wires for power is a no brainer; pantographs and the like are known tech.
>>Running overhead wires for power is a no brainer; pantographs and the like are known tech.
All the moving parts (rather more than you may initially think) required to make overhead lines work for terrestrial trains will need modifying for the incredibly abrasive environment.
Gravity plays a large part in making overhead traction power supplies work here on Sol 3.... slight problem with that on the mun IIRC in that there is much less of it around to keep things pointing generally downwards. Oh and the support gantries will need fixing as well... which is a whole new field of pain.
I would suggest overhead wires for power, on the mun, is far from being a "no brainer".
FLOAT looks like a much more promising system - Maglev, too, is proven tech these days, has fewer moving parts required for traction plus it shouldn't be too hard to keep the induction coils cool (at least 14 days out of 28; granted the rest of the time it might be more tricky)
Yeh - the Vacuum is a mixed blessing. In the dark times it helps by there not being convection to worry about heating up the superconductor, however it means that during the daytime any of the structure hit by unattenuated sunlight has to radiate that energy back to space or get hotter... which isn't good news for many reasons.
Trolley poles don't have that many moving parts. Make the wear points replaceable (as they do down here on Earth), and put a boot around necessary places with a charged brush to repel the abrasive particles "stuck" to the wire. I'm pretty sure that human ingenuity can make something like this work.
Also, schedule trips for times when activity isn't kicking up a lot of dust. Unlike here on Earth, there is no atmosphere to hold particles for hours or days, they should settle out in seconds.
Running overhead wires for power is a no brainer; pantographs and the like are known tech.
For rail though. Where you have a highly consistent distance between wire and rail, and the steel wheels don't compress or bounce.
Sweden have trialled overhead lines for HGVs, and they do work - ishly. But because trucks have bouncy pneumatic tyres they have to keep the line and pantograph at much higher tensions. This leads to more wear and a higher likelihood of breakage. Or dust clogging the joints on the pan.
On the Moon.. with a moderately rough surface (unless it were groomed and paved smooth, which is also a topic of research), it's highly likely that downed wires would be a common occurrence when a vehicle hits a rut at the wrong angle and stretches the OHLE a bit too hard. In which case your stranded vehicles would need battery-powered life support that can last until rescue arrives. Or a battery backup good for at least 50% of the journey (to reach the destination or to get home). At which point you're carrying a battery anyway...
Overcoming the rail abrasion issues seems easier in the long-run (although self-contained BEVs are inevitable in the early days, just as our railways were built using horse and cart), and also lowers the energy requirements of the system, since steel-on-steel uses an order of magnitude less energy than flexible tyres rolling over arbitrary surfaces. Whilst moon dust is highly abrasive, we have to remember that gravity is 16% of Earth's, lowering the pressure and abrasion on the rail. The bigger problem with rails on the moon is going to be thermal expansion.
San Francisco has long used Electric Trolley Buses with standard rubber tires and electric motors powered by overhead wires. It is actually less trouble than the tracked Muni trains.
https://www.sfmta.com/getting-around/muni/munis-electric-trolley-buses
They actually use trolley poles, I shouldn't have said "pantographs and the like are known tech", it gave the wrong idea of what I meant.
Yes, the SF version runs a battery pack so they can go "off wire" for a bit to get around obstacles.
That's a lot of infrastructure to build. Even running "tracks" might be pointless once you pinpoint a safe route around craters, boulders etc. and just follow that same route every time. Just rover style wheels that drive on the surface.
As for power the Moon is ideal for solar, especially if you mostly only travel during the "day" but it could even be made to work during the night if it had to. If the "trains" have detachable battery trailers then you could have waypoints with small solar farms every once in a while that charge up one or more trailers. Your train arrives and your battery trailer(s) automatically detach themselves and drive over to plug into the solar array (even if it is dark the sun will come out eventually) and one or more charged up trailers automatically drives over and attaches, then the train continues on its journey.
If you don't really care how fast the train goes, it could probably drive itself on solar. Might need some lightweight solar trailers that spread a fairly large array of panels if the "train" is hauling something heavy, and it would only move two weeks out of the month, and maybe it only travels at 1 kph, but it would work. I guess it depends on why someone thinks we need a "railroad" on the Moon. What exactly are we going to be hauling, and over how long of a distance? And why aren't we landing/launching or processing from wherever this stuff is going/coming from, instead of hauling it large distances across the Moon?
> Step 1 : eliminate the incredibly abrasive influence of Moon regolith on railroad tracks.
> We'll continue when you've solved that.
Giant mirror in space, focus the sunlight and just(!) glass a path from A to B. Fix any crazing due to day/night heating/cooling stresses with a quick pass to spruce it up at dawn.
Make mirror from thin film across flimsy framework, assembled (inflated) in orbit: cheap and easily replicated, light weight to be shipped up in a multipack. We are supposed to have a staging station in Lunar orbit, so just chuck another one out the door from there as and when.
"Step 1 : eliminate the incredibly abrasive influence of Moon regolith on railroad tracks.
We'll continue when you've solved that."
Tunnels. Bore a tunnel and sweep it clean, it will stay clean so long as you don't let in Charlie Brown's friend Pig-Pen.
Remind me: wasn't there some research recently, in which it was attempted to grow earth seeds in lunar regolith? I have a vague idea that it was too sharp or spiky to provide a secure mechanical support for the growing seedlings, but I could be misremembering.
Yes, it was thale cress and the plants seemed stressed at growing in lunar regolith material. Surprisingly, they didn't test any actual food crops and l think that was a mistake. Link below:
https://www.nasa.gov/humans-in-space/scientists-grow-plants-in-lunar-soil/
Terrestrial plants form relationships with the soil fungi they have co-evolved with... The fungi have an impressive chemical toolkit for breaking down inorganic substrates and accessing nutrients. Consider how fine the mycelia are compared to even the thinnest of plant roots; their surface area is immense.
In return the plants supply sugars to the fungi. Usually. Some plants are parasitic, just as some fungi are.
Vaguely remembering now, I recall when I read the article wondering whether the results would have been happier had more of a terrestrial biome been included in the lunar regolith, rather than just using the regolith as a plant support.
(Makes me wonder about The Martian's potatoes, too...)
I'm guessing that as the The Martian's spuds were growing in the astro-poop there's no need for fungi*, sterile regolith mixed in being mostly to provide a bulked up growing medium & drainage.
Though I'd also hazard that while they might well grow ok they'd not react well to having sharp edges ground into their roots if walked over.
* Do we have any bio-stuff experts with a paragraph to share lurking here?
It was also surprising to me that those NASA scientists did not try out growing the plants in a mixture of the lunar regolith material with sterilised human liquid and solid wasted as featured in The Martian (book and film). That would probably have made for a noticeably better plant compost.
Just make sure not to drive into the Sea of Thirst!
... just not a successful re-entry. It achieved orbital velocity, and the only reason it didn't actually orbit was because it was never intended to.
The engineers that gave us Falcon 9, a reusable rocket that has met its stated goal of making spaceflight seem as boring as civil aviation, appear to know what they are doing.
《What about Musk's own Hyperloop.》The Boring Company came to my mind too.
《Now all that is needed is a Fat Controller》
His Muskiness is showing signs of middle aged spread tending to decidedly porky so position already filled. (He obviously now needs a different kind of special-K. ;) Obviously wouldn't require any retraining for role.
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I imagine cutting open trenches and laying prefabricated tunnel sections in the trenches and backfilling the trenches might be a practical approach.
You get thermal stability and the tunnel could be be dust (regolith) free (a very slight gas pressure could keep the dust from leaking in through small imperfections.)
Obviously such a tunnel as on earth would carry more than rail traffic (comms, power, water, effluent [for recycling], air etc.)
I imagine some sort of lunar cement/concrete could be used to make the tunnel sections.
Not sure an actual rail is required - in a tunnel a trolley bus type vehicle with solid tyres might be adequate.
In a tunnel you could even use a canal if you were producing and transporting enough water and kept it just above 0°C so the vapour press is low (600-800Pa.) Lunar barges. ;)
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I always imagined a trebuchet style devices flinging stuff over the moon's surface - the 1/3g gravity and reduced curvature would give you a fair range and the lack of an atmosphere should mean greater precision and accuracy but with no parachutes which is ok for robust payloads but a bit hard on passengers. ;)
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Moving skyhooks might be another option. A fairly massive satellite in a low circumlunar orbit trailng a cable reaching to near the surface would rapidly pass over the lunar terrain(sic) but could be contrived to pick up cargo in much the same way moving railway trains used to pick up mail bags.
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Ask a silly question I guess.
If they emulate Caifornia's HSR boondoggle, it'll be over 10 times over budget, and they won't even have the right-of-way nailed down for the first (and least needed) portion of the track a decade and a half after construction is authorized to start. Eventually, they will open the first 171 miles of the track over a quarter century after it was authorized (if they are lucky), at a cost of at least 40 billion dollars, and absolutely nobody will use it.
171 miles of HSR for $40 billion?
That's only $234 million per mile. We've managed to make ours cost about $500 million per mile! Costings from this article.
That's ambiguous because US military contractors have been known to do this:
" The year is now 1951: My first engineering job is at Boeing. I’m designing parts for their new B-52A bomber. I use my own drafting instruments as I work at a huge drawing board. But the company provides me with a special ruler. .... Its inches are divided into tenths. And each tenth is subdivided into tiny slices, two one-hundredths of an inch wide. You see, Boeing conceived the airplane itself in one-inch sections. The B-52’s body was – is – one thousand, nine hundred, and twelve inches long.
" Boeing had created its own decimal system within the company. Just think how much labor they cut when we didn’t have to keep multiplying and dividing by 12! How much more time did we save when we didn’t have fractions like three-eighths of an inch? ... "
https://engines.egr.uh.edu/episode/3292
The idea of the United States building a railway on the Moon is laughable given that they're apparently incapable of building a railway in the, err, United States.
Now, if they'd asked for China to tender... there's a country that knows how to get stuff built (if you don't mind a bit of slave labour).
I was going to suggest the Japanese. Given their track record (oh dear) of building Mag-lev railways they at first glance appear to have more relevant experience than a defense contractor such as Northrup Grumman... but then I thought, what's the difference between a Mag-lev railway and a rail gun *really*?
> what's the difference between a Mag-lev railway and a rail gun *really*?
Not wanting to be pedantic[1] apparently[2] you are thinking of a "coilgun", as a "railgun" has the projectile as part of the circuit, meaning it is in contact with the rails during the entire acceleration phase. And has potential (ho ho) for lovely sparks and plasma, so pretty.
[1] oh, who am I kidding?
[2] personally, I reckon they changed the names on us, 'cos I've been using "railgun" instead of "coilgun" since the 1970's! Anyway, that first link is to a PDF on a dot-mil site, just to reassure you that I'm not just relying on Wikipedia (the next two links); plus the PDF also discusses cool stuff like giant lasers - sadly, without sharks.