[Skunkleton]

First I am reading about nuclear engines applied to Starship. I wonder if it would be more practical to launch the reactor, fuel, and propellant into orbit using conventional rockets. Later a mission could pick up this Nuclear rocket engine and use it as a sort of booster while not inside a strong gravitational field. Ofc that doesn’t sound like Starship at all.

[ianburrell]

Nuclear rockets are useless for launching things into orbit. They don't have the thrust-to-weight ratio to get off the ground. Nuclear rockets are useful because they have high specific impulse which means using less fuel for thrust.

[zare_st]

Exactly opposite of what the person above you is talking about.

[sonicanatidae]

shhh...cage match.

[therein]

One of the core teachings of Kerbal Space Program.

[Kim_Bruning]

However, in KSPI [1]: Consider the combination of a nuclear lightbulb with compressed air as the reaction mass: Surprisingly good midpoint qua TWR and ISP! If you install a compressor you can get some pretty interesting SSTOs out of it. Whether these would work IRL is a different question, of course. [2]

Nuclear lightbulb is of course highly theoretical, but scientifically/engineeringly plausible at the least. [3]

[1] https://forum.kerbalspaceprogram.com/topic/173818-181-1122-k...

[2] https://xkcd.com/1244/

[3] https://en.wikipedia.org/wiki/Nuclear_lightbulb

[matheusmoreira]

It's that close flyby of the sun that always gets me.

[scythe]

Did you read to the end? That's the idea he ends up with: only use nuclear propulsion for space-to-space travel where you don't care as much about shielding.

[Skunkleton]

I make no claims about my reading comprehension. That last bit seemed too narrow to me. Once you have all the bits in orbit, shielding doesn’t seem too onerous. Is the claim that even space-space shielding + reactor is too heavy to be worth the advantage of the nuclear drive?

[marsokod]

No, they are saying that the nuclear drive shall be reserved to a shuttle that remains in space. At that point, it makes much more sense as you can really use the nuclear drive to its full capabilities.

> If we need the full performance advantage of nuclear propulsion, we should design a spaceship that is intended for it from the get-go. It never lands, only going from orbit to orbit, so there is no need for heat shielding, flaps, high thrust engines, thick steel structure or aerodynamic shaping requirements.

[simonh]

In space if you’re careful you only need a plate of shielding between the drive and the crew/cargo section.

[GordonS]

Isn't radiation from cosmic rays going to require very heavy shielding?

[simonh]

Sure, but that's got nothing to do with any additional requirement due to your propulstion system.

[Kim_Bruning]

That was (part of) the original plan, post Apollo program. Somehow it got stripped down to to just a space shuttle. :-(

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

[psunavy03]

The "we haven't solved all of our problems on Earth yet" crowd . . . as if we ever will.

[lifeisstillgood]

Hell we put humans on another planet, we can fix the stuff down here if we really want

[jerrysievert]

which other planet have humans been to? I can only remember humans making it to earth, which isn't that far of a journey ... from earth.

we put humans on a moon, and we've put robots on another planet.

[Kim_Bruning]

It's a different kind of problem, unfortunately.

[matheusmoreira]

That's exactly what I do in Kerbal Space Program.