this post was submitted on 31 Jul 2023
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Wasn't the Moon's gravity low enough that you could basically use electromagnetic cannons to launch payloads from the surface all the way out of lunar orbit?
In the absence of an athmosphere and with only 16.6% of Earth's gravity, achieving orbit from the Moon isn't simply "not as though" as doing so from Earth, it's incredibly less so (maybe 100s of times, though I don't really have the numbers so take it with a grain) - just compare the full size (including boosters) and fuel payload of the vehicle needed to put 3 people on the Moon and those of the vehicle needed to bring them back to Earth (granted, the first vehicle had to also carry the second one, plus food, water and air for the first part of the trip).
Being at the bottom of a 1G well and having to also overcome quite a lot of air drag to get out of it massivelly adds up to the energy needed to do so, both because the whole getting out of a gravity well thing is a logarithmic progression (as you need to spend fuel to haul up the fuel that's going to be used higher u), so overcoming 6x the gravity doesn't just mean using 6x the fuel, and on top of that there are the the losses due to drag in the lower athmosphere which for example severely limit initial launch speeds (as drag is directly proportional to velocity).
If you haven't read it yet, try 'The Moon Is a Harsh Mistress,' by Robert Heinlein. It was written in the 1960s, so some of the tech is a teeny-weeny bit outdated but the story is still great.
I don't know anything about EM canons but between the moon having a relatively weak gravity well and being within Earth's gravity well, I'd think any method would be much easier to use when it comes to transport to Earth
Ok so I did a small bit of research and found optimistic estimates from groups promoting this of $800kg. You can’t just throw shit at earth, you have to put it down safely. In reality what makes sense is manufacturing stuff that you then don’t have to bring up to the moon, or to mars, or anywhere else off of earth. You build it on the moon instead.
IDK $800/kg sounds pretty great compared getting from Earth into Earth orbit at $54,000/kg. Doing something like manufacturing and launching satellites would probably become pretty viable once it's set up.