>This kind of nuclear research is, thankfully, over.

Nuclear pulse propulsion is the only currently viable technology that could be used to make humans an interstellar species. It would also allow us to practically ship up enough materials to build self-sustaining habitats in near space. It is extremely unfortunate that this kind of research is over.

Fun fact: the background radiation levels introduced by nuclear propulsion would actually have a very slight positive health effect on humans according to more accurate radiation hormesis models, rather than the very small negative effects suggested by more naive no threshold models.

Radiation hormesis models aren't "more accurate." The long-term effects of small amounts of radiation are simply not well understood. It could be good, it could be bad, it could be neutral.

The far bigger problem for launching Orion from Earth is the electromagnetic pulse frying every satellite above the horizon and a bunch of stuff on the ground.

I agree that nuclear pulse propulsion would be awesome to have. However, as far as I know radiation hormesis is a hypothesis that is still disputed.

On the other hand if we'd gone all-in on nuclear pulse launchers, there would have been no incentive for companies like SpaceX and Blue Origin to develop reusable conventional rockets which will hopefully achieve the same result at lower environmental and perhaps also financial cost.

Even if you had effective nuclear pulse propulsion, you'd still need reusable chemical launchers to get them off the surface of Earth. Nuclear pulse engines are generally not something that you start up inside an atmosphere, for both safety and efficiency reasons.

The post I was responding to strongly implied using these for launches.

> ..It would also allow us to practically ship up enough materials to build self-sustaining habitats in near space..

How can chemical rockets with ~3km/s exhaust velocity ever achieve the same result? Also if we had gone all in on this concept maybe today SpaceX and BO would be working with a much more promising technology.

It depends how reusable nuclear launchers would be. A less efficient launch system in terms of ISP that uses thousands of times cheaper fuel and e.g. is 10 times more reusable might be very competitive.

I would rather classify that as "unfortunate". Yes there are obviously biological harms in radiation exposure but that is what science & engineering is for. We know the power of nuclear energy so in order to harvest it, the right thinking should have been like "How can we safely extract it so that it does harm people in the mix?" rather than "Oh its harmful to humans so obviously we should give up and not use it".

Current fission startups are working on versions of reactors which eliminate most of the harmful byproducts in the process.

I'm not sure all of the opposition to nuclear research is about dangerous byproducts from the typical situation(s). It is about the improbable problematic situation which lead to exponential disaster that are scary, and, even if improbable, inevitable...

well you have rockets which blow up on launch sites. so..

Yay, chicken little!