this post was submitted on 08 Apr 2025
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[–] someone@hexbear.net 19 points 1 week ago* (last edited 1 week ago) (4 children)

It's an interesting idea on worlds with lower gravity and little-to-no atmosphere, like Mars or the Moon. But frankly the fuel needed to get to Mach 1 on Earth is a pretty small fraction of the fuel needed to get to orbit. Orbital rockets get to mach 1 really early in flight. Maglev-assisted launch has never really been seriously developed because it's simpler to just design a rocket to carry a little more fuel.

Also, a lot of rockets aren't designed to handle horizontal loads. Neither are a lot of satellites with big mirror segments, like spy satellites or space telescopes. They live their lives either vertical on Earth, effectively-vertical while in flight due to acceleration, or in microgravity on deployment into orbit.

There's also the issue of being able to reach multiple orbital inclinations for different purposes. The fuel needed for dogleg maneuovers after launching from a maglev track could be more than needed to simply launch vertical from a conventional pad, and is way cheaper than building launch tracks for all the common inclinations.

Maglev-assisted launch also has the issue of engine start-up failures leading to disaster. A conventional liquid-fueled rocket will usually run for a few seconds while still clamped to the launch stand while the flight computers do automatic diagnostics. Issues on start-up mean an automatic safe shutdown is possible prior to releasing the launch clamps. If there's an engine start-up issue with a rocket late into its maglev launch, failure changes from "unload the propellants and try again tomorrow" with a vertical rocket on a pad to "yeeting an out of control rocket and its valuable payload into whatever is downrange".

[–] miz@hexbear.net 6 points 1 week ago (1 children)

the fuel needed to get to Mach 1 on Earth is a pretty small fraction of the fuel needed to get to orbit.

how does that square with

The platform would accelerate rockets to speeds above Mach 1 as rockets burn most fuel at the beginning of a flight,

[–] someone@hexbear.net 7 points 1 week ago* (last edited 1 week ago)

It's absolutely true that most rockets' fuel is burned early. But it all comes back to cost and design simplicity. Stretching fuel tanks in a rocket design upgrade is comparatively simple, compared to the eye-watering cost of building a maglev track that can handle a heavy-lift rocket and the nuclear reactors that would be needed to power it.

Also, mach 1 is pretty slow for a rocket. Most rockets reach that in about a minute after launch. Objects in low earth orbit (like the ISS) are travelling at the equivalent of sea-level mach 28.

take your sciency knowhow and shove it, i want the giant railgun space cargo launcher strictly because its fuckin cool and i support cool shit bein done

[–] yogthos@lemmygrad.ml 4 points 1 week ago

I also expect that a moon launcher would probably be the most practical. There's no atmosphere to worry about, and very low gravity. Earth based launches like this do face a lot of challenges, but I guess we'll see if they manage to produce anything interesting. Even if they can't make it practical for use here, the research and development that will go into it will be useful for building this on the moon later.

[–] Awoo@hexbear.net 1 points 1 week ago* (last edited 1 week ago) (1 children)

If there's an engine start-up issue with a rocket late into its maglev launch, failure changes from "unload the propellants and try again tomorrow" with a vertical rocket on a pad to "yeeting an out of control rocket and its valuable payload into whatever is downrange".

Couldn't you have two tracks? One track for cancelling late and one for yeeting? If the mission gets cancelled then it goes into a slowdown track loop, if the mission does not then it gets yeeted.

[–] someone@hexbear.net 2 points 1 week ago

Probably, but that just adds even more to the cost, construction time, and land area needed for each launcher complex.

All said, maglev launchers on Earth are just an impractical solution that don't really solve any of the real problems with chemical rockets. Basically every problem with chemical rockets launching from Earth that is solved with a maglev launcher can be solved way cheaper and way faster by just designing rockets to carry a little more fuel.