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Read a sci-fi book recently with that being a central plot point. Reasonably advanced species unable to escape the gravity of its home world. There is also a de

Read a sci-fi book recently with that being a central plot point. Reasonably advanced species unable to escape the gravity of its home world. There is also a dearth of fissile material in the solar system that prevent a "nuclear option". Book was written as a bit of homage to "The Mote in God's Eye" with wanting to leave to planet being seen as a "Crazy Eddie" idea. https://www.goodreads.com/book/show/59554147-cold-eyes https://www.goodreads.com/book/show/59554147-cold-eyes

Retric 3y ago
It’s clearly more difficult, but authors are a few individuals briefly thinking about a problem not entire civilization attacking the problem across generations. My first thought is balloons work based on relative densities so they can still reach very low density air on a high gravity world. That doesn’t help much with rockets, but firing a gun or using something like spin launch is much easier if you can start from very low atmospheric pressure. No idea what actual engineers could come up with.
- neolefty 3y ago
  Mostly it's moar stages. Each stage of a kerolox engine can get you about 5 km/s, and LEO is about 8 km/s, so two stages works pretty well. Velocity for LSEO (low super-earth orbit) might be 11 km/s, so you'd need a third stage, and each stage would be 3-5 times the size of whatever it's launching.
  - Retric 3y ago
    It’s not that simple a falcon 9 upper stage on a 5g super earth would collapse from its own weight during takeoff. It’s a double hit as your lower stages are also losing ~5g’s of acceleration due to gravity. So if you want to add 3g the entire rocket needs to be able to withstand an effective 8g, and you need a rocket engine + fuel to provide 8g’s worth of force. On top of this the time between each stage becomes extremely costly.

3 ms·

Read a sci-fi book recently with that being a central plot point. Reasonably advanced species unable to escape the gravity of its home world. There is also a de

by daltont 3y ago

Retric 3y ago
It’s clearly more difficult, but authors are a few individuals briefly thinking about a problem not entire civilization attacking the problem across generations. My first thought is balloons work based on relative densities so they can still reach very low density air on a high gravity world. That doesn’t help much with rockets, but firing a gun or using something like spin launch is much easier if you can start from very low atmospheric pressure. No idea what actual engineers could come up with.
- neolefty 3y ago
  Mostly it's moar stages. Each stage of a kerolox engine can get you about 5 km/s, and LEO is about 8 km/s, so two stages works pretty well. Velocity for LSEO (low super-earth orbit) might be 11 km/s, so you'd need a third stage, and each stage would be 3-5 times the size of whatever it's launching.
  - Retric 3y ago
    It’s not that simple a falcon 9 upper stage on a 5g super earth would collapse from its own weight during takeoff. It’s a double hit as your lower stages are also losing ~5g’s of acceleration due to gravity. So if you want to add 3g the entire rocket needs to be able to withstand an effective 8g, and you need a rocket engine + fuel to provide 8g’s worth of force. On top of this the time between each stage becomes extremely costly.