In that case aliens from a super Earth would be unable to get off it unless they decided to salt their biosphere with fissile waste. NERVA is at least contained if it works properly.

So no space program from a super Earth until they figure out not just fusion but compact high density fusion that could fly. You’d need stuff like in The Expanse, or at least in that rough ballpark.

Using fission is something they probably wouldn’t do unless they faced an existential reason forcing them to go to space, like deflecting an asteroid.

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m4rtink 3 hours ago | parent [-]

I think a launch loop would still work, even on a Super Earth:

https://en.wikipedia.org/wiki/Launch_loop

Or potentially beamed power for launch, so you don't kug a power source. But in any case, indeed much harder. :)

	▲	api 2 hours ago \| parent [-]
		Yeah. I’m a little obsessed with Orion though. The fact that the math works on that lunacy. The good old devil’s pogo stick. If you could make pure fusion bombs it would be maybe politically viable, especially if you also use superconducting magnets to make it less just brute force. You’d still induce a little radioactivity from neutrons but it would be short lived and not even close to fissile fallout bad. To see that thing launch. From somewhere very remote though, probably Antarctica. And from many miles away, and probably with welders glass. But damn. That would be epic.