Project Orion

Related:

Interstellar nuclear-powered transport (1968) [pdf] - https://news.ycombinator.com/item?id=28132756 - Aug 2021 (34 comments) - thanks antondd!

Orion Project [pdf] - https://news.ycombinator.com/item?id=22691219 - March 2020 (1 comment)

Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf] - https://news.ycombinator.com/item?id=12705705 - Oct 2016 (99 comments)

Project Orion (nuclear propulsion) - https://news.ycombinator.com/item?id=9025611 - Feb 2015 (11 comments)

Project Orion (nuclear propulsion) - https://news.ycombinator.com/item?id=3019627 - Sept 2011 (1 comment)

Project Orion is one of the stupidest, most wonderful ideas ever conceived in America. - https://news.ycombinator.com/item?id=261348 - July 2008 (6 comments)

That's less than I expected - are there other threads?

Relevant xkcd: https://xkcd.com/2423/

An other quite interesting concept (also a little less "out there" and actually, successfully tested) is the NERVA engine, also linked at the bottom of the article[1].

It uses a nuclear reactor to heat up a single propellant (liquid hydrogen) which then rapidly expands as it goes out the nozzle at the end, resulting in quite high specific impulse and is more efficient than a chemical rocket.

If we want to go really far out in terms of crazy rocket designs, there is also the concept of the nuclear salt-water rocket[2][3].

This one uses enriched plutonium or uranium salts, dissolved in water, inside a neutron-absorbent fuel tank design. The water is pushed out through a pipe, where an uncontrolled chain reaction starts. If it goes fast enough, it explodes right inside the engine bell, pushing the rocket. The proposed design in the original paper is supposed to generate hundreds of gigawatts of thermal power. This is comparable to the Chernobyl reactor #4 when it exploded, but unlike Chernobyl (which only exploded once) or the pulsed Orion engine, it could run continuously. The stuff that flies out of the nozzle easily reaches escape velocity of the solar system.

[1] https://en.wikipedia.org/wiki/NERVA?useskin=vector

[2] https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket?uses...

[3] Obligatory Scott Manley video: https://www.youtube.com/watch?v=cvZjhWE-3zM

There was a classic science fiction story with a twist on this idea; a low tech species was about to be discovered by a more advanced species. And according to the rules of the more advanced species, any planet that wasn't capable of space travel would become a client or vassal, and a planet with space travel would be seen as a peer. The protagonist built a pusher style rocket using an explosive, and launched the lightest person he knew into orbit, who happened to be his girl friend.

I keep thinking this was a Larry Niven story, maybe someone here is familiar?

Edit; another classic story was the novel Footfall by Niven and Pournelle which featured launching the USS Missouri into orbit on an Orion style pusher to battle the invading aliens.

That doesn't sound part of Niven's Known Space canon.

However, 'Footfall' by Niven and Pournelle does have an Orion, as does Invisible Sun, by Charles Stross.

Nothing obvious in [0]

[0] https://en.wikipedia.org/wiki/List_of_stories_featuring_nucl...