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Comment by daltont | Hacker News Reader

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

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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.

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.

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.

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