If we are going to build something really big, perhaps a interplanetary space station for people to live on for years on their way to Pluto (OK not technically interplanetary - well not any more), perhaps a interstellar Orion Drive, is it more practical to build it in low earth orbit or the moon?
Launching such a large craft in one piece is not (yet) practical from Earth. Assembly in low earth orbit requires many small launches and in space assembly, something we have done with the ISS so we have experience. But I want to consider such manufacturing and assembly on the moon, much lower gravity to launch from, plus resources available on the moon, reducing the number of launches, but requires a base on the moon that can gather and process the resources.
It would appear there may be a tipping point where if the project is large and or numerous enough assembly on the moon starts to make sense, perhaps combined with assembly in lunar orbit. Just water for manufacturing fuel on the moon could make a large difference. But what other resources could we reasonably get and use from the moon and is it even a practical consideration.
The logical problem with building it on the Moon is that you’re putting your spaceship in another gravity well for no good reason.
To build something on the Moon you still have to launch it from Earth and into orbit, and then fly it to the Moon, and then land it there, and now you need to launch it from the Moon. If you assemble it in orbit, you don’t need the energy to fly the parts to the Moon and launch them out of the Moon’s gravity. Sending all this to the Moon makes everything vastly harder and more expensive to do - like, literally ten times more expensive, at least.
The Moon has no resources worth going there to find. If you can find fuel there (which even if possible will be very difficult and resource intensive) that’s cool, but there’s more to a spaceship than fuel.
The real question is where the parts are actually being manufactured, not assembled.
If they’re being manufactured on the moon, then it may well be less expensive to build the entire thing on the moon and just launch it from there.
If you have orbital factories, etc… it wouldn’t make a lot of sense to drop them onto the moon to build it.
And finally, if your factories are on Earth, you probably just want to pay the minimum necessary to get them out of your own gravity well, and not to get them all the way to the moon, and then have to launch them from there as well, so building the components as large as you can on Earth and then launching them into orbit is probably the right approach (as exemplified by the ISS).
More than thirty years ago, I read a book by a Princeton physics professor named Gerard K O’Neill, who described how large space stations could be built at the L4/L5 points using materials taken from the moon and launched into space using a mass driver. You might be able to do something similar to build interplanetary spaceships.
The Moon certainly does have resources – there are minerals in those there rocks, and plenty of ore you don’t have to haul out of an earth-sized gravity well.
see here, for instance, or in O’Neill’s proposals for construction of his space colonies using lunar resources as dewey Finn notes:
There are still plenty of unknowns, but it’s probably energetically cheaper to manufacture materials from the raw materials on the Moon than on the earth and get them to orbit. It might be easier to do it on the Moon than in orbit.
There are plenty of raw materials on the Moon to support factories creating space vehicles. But we would most likely need to develop a system of space elevators between Earth and the Moon to make them economically sustainable. It will be a long time before that is achievable.
You mean Helium-3. Helium-3 fusion is the cleanest form we know of, and looks like it eliminates neutron flux escape (and corresponding neutron activation of the reactor’s own materials), but it’s also the highest-temperature and probably hardest one to attain. So, expanding on what Darren Garrison points out, not only do we have to figure out controlled fusion, we’d have to figure out the hardest kind to attain and control.
But a dang nice idea. I’ve always hated the thought that for the most feasible forms of controlled fusion, your reactor vessel and containment would itself eventually become tons of high-level nuclear waste. :mad:
What’s the cost of sending an entire manufacturing chain of facilities to the Moon and setting it up there? That sounds like a bigger project than actually building the spaceship.
Depends on how big and elaborate the spaceship is. The orbiting colonies proposed by Gerard K O’Neill that I mentioned would be enormous and really not possible to lift from Earth.
I’m sure Stranger will stop by shortly. Many of you are more knowledgeable than I. I know for some time my son has advocated use of the Lagrange points, but I believe other folk opined as to the impracticalities involved.
The point is that you don’t just build ONE spaceship there; you set up a manufacturing assembly line that allows you to build multiple such ships. Then, the “cost” of sending materials from Earth to Luna is amortized, if you will, over several ships.
Plus, if you are REALLY smart about it, you send just the minimum necessary robotic equipment to manufacture a manufacturing plant from Lunar resources, and then let the robots do their thing.
You don’t want to get your raw materials from Earth nor Luna. Asteroids are where it’s at. Not only do they have more easily-accessible carbon than Luna, and more iron than either, but they also have no gravity worth worrying about.
In fact, the largest-scale projects probably aren’t even a matter of building them at an asteroid, or on an asteroid, but in it and out of it. Take an entire asteroid, hollow out living spaces, and that’s your ship or station.
I’m honestly curious as to how many ships that would be, because I don’t think it’s 20. Or 50. I think it’s like hundreds and possibly thousands.
Let’s be very clear; the Moon is not a fantastic place to find, well, anything except rocks and dust. Such minerals as are there are not in convenient veins. You need an absolutely gigantic enterprise there just to process the millions upon millions of tons of rick you’d have to dig up to get the metal you need. (How you’d get anything else I do not know; there is nothing there from which to make plastics, for instance.) To create all or even most of the materials on the Moon to construct any number of spaceships would require the construction of a lunar base so massive in scope and complexity that it defies imagination - you would need either trillions upon trillions of dollars, an effort probably exceeding the capacity of the entire world to finance, OR you’d need some pretty damn futuristic advances in robotics. It would take so long to build it that the spacecraft you were planning on building would be outdated by the time you got the facilities ready.
The creation of anything complex in the world we actually inhabit is supported by the existence of productive capacity far beyond the scope we assign to it at first glance. Think of something simple you’ll need to make your spaceship - let’s say welding equipment. You can’t make it without welding something. Just how were you planning on doing that? It’s not just that you need welding machines (specially designed to work on the Moon) but you need welding consumables. TONS of them - welding wire and welding gases, for the most part. Those things are not on the Moon. You need screws and nuts and bolts. You need paint and paper and vinyl to make the seats on the ship. You need, in other words, an economy - you’re talking about building a city on the Moon, really, unless, again, we’ve got some pretty damn smart robots to do it for us, and even then they lack essential resources that must be sent there from Earth.
Moon dust is a real pain to deal with. It sticks to everything, carries a charge, gums up seals, and might be a hazard to human health. I’d think you’d want to keep the construction of space ship components far away from the lunar surface.
