3 ms·

You’re going to have a hell of a difficult time trying to construct anything that tall on a high-g planet. The taper ratio between the base and the top would ha

You’re going to have a hell of a difficult time trying to construct anything that tall on a high-g planet. The taper ratio between the base and the top would have to be enormous – likely a sizeable fraction of the radius of the planet! Though I guess it would have to be anyway so you have somewhere to attach all those first-stage engines…

jstanley 3y ago
If you're allowed to build it tall enough, just don't even light the first stages. Launch the final stage directly from a high enough altitude that it can escape on its own.
- Sharlin 3y ago
  Well, yeah, but building something tall enough to reach the synchronous orbit is impossible even on Earth, there’s no material with even a thousandth of the compressive strength required. Space elevators are only possible because they’re tensile structures and the “bottom” that supports the weight of the entire structure is up there in a low gee environment. Remember that just getting outside the atmosphere is the almost trivial part of rocketry compared to the problem of having to then accelerate to >= orbital speed fast enough to not fall down! And anyway you’d have to dismantle the planet to build your launch tower, which I guess would solve your problem, in a fashion. Though – whatever you turned your planet into would just have an annoying tendency to rapidly collapse back into a ball.
  - usrusr 3y ago
    If you really have a lot of time for the project (starting early in the star's burn?), you might try using photovoltaics to move a lot of mass across the surface to ahead of where tides would accumulate, slowly speeding up the day/night cycle. The faster you spin, the flatter your geoid and you should probably stop accelerating before your entire equator region goes interplanetary.
  - eru 3y ago
    On earth, you could use active support to build your tall structures, then you don't need exotic super-materials. See eg https://en.wikipedia.org/wiki/Space_fountain https://en.wikipedia.org/wiki/Space_fountain

jstanley 3y ago

If you're allowed to build it tall enough, just don't even light the first stages. Launch the final stage directly from a high enough altitude that it can escape on its own.

Sharlin 3y ago
Well, yeah, but building something tall enough to reach the synchronous orbit is impossible even on Earth, there’s no material with even a thousandth of the compressive strength required. Space elevators are only possible because they’re tensile structures and the “bottom” that supports the weight of the entire structure is up there in a low gee environment. Remember that just getting outside the atmosphere is the almost trivial part of rocketry compared to the problem of having to then accelerate to >= orbital speed fast enough to not fall down! And anyway you’d have to dismantle the planet to build your launch tower, which I guess would solve your problem, in a fashion. Though – whatever you turned your planet into would just have an annoying tendency to rapidly collapse back into a ball.
- usrusr 3y ago
  If you really have a lot of time for the project (starting early in the star's burn?), you might try using photovoltaics to move a lot of mass across the surface to ahead of where tides would accumulate, slowly speeding up the day/night cycle. The faster you spin, the flatter your geoid and you should probably stop accelerating before your entire equator region goes interplanetary.
- eru 3y ago
  On earth, you could use active support to build your tall structures, then you don't need exotic super-materials. See eg https://en.wikipedia.org/wiki/Space_fountain https://en.wikipedia.org/wiki/Space_fountain