[bserge]

People are afraid of nuclear power plants. You think they'd ever allow nuclear space flight?

Think of the 0.05% chance of launch failure, all that radioactive shit spread in the air, alongside all the other dangerous shit we already put there willingly!

[WJW]

This would have been a much more convincing argument if we had not already launched several nuclear reactors into space.

[cesarb]

> if we had not already launched several nuclear reactors into space.

AFAIK, we haven't. What we have launched several of are RTGs, which other than using nuclear fuel, are a completely different technology, one which is much easier to completely shield. IIRC, there have even been cases where a rocket containing a RTG failed, and the RTG was found intact and could even be reused.

[perl4ever]

>AFAIK, we haven't

From Wikipedia, there are (or were) over 30 reactor (not RTG) powered satellites. One program was called "US-A" and another "SNAP-10A". These were launched at least from the 1960s through the 1980s, by multiple countries.

"The US-A programme was responsible for orbiting a total of 33 nuclear reactors"

"Normally the nuclear reactor cores were ejected into high orbit (a so-called "disposal orbit") at the end of the mission, but there were several failure incidents, some of which resulted in radioactive material re-entering the Earth's atmosphere."

"The higher-orbiting TOPAZ-containing satellites were the major source of orbital contamination for satellites that sensed gamma-rays for astronomical and security purposes, as radioisotope thermoelectric generators (RTGs) do not generate significant gamma radiation as compared with unshielded satellite fission reactors"

https://en.wikipedia.org/wiki/US-A

"The [SNAP-10A] reactor measures 39.62 cm (15.6 in) long, 22.4 cm (8.8 in) diameter and holds 37 fuel rods containing 235U as uranium-zirconium-hydride fuel.[15] The SNAP-10A reactor was designed for a thermal power output of 30 kW and unshielded weighs 650 lb (290 kg)"

https://en.wikipedia.org/wiki/SNAP-10A

[WJW]

Sure, but the (perceived) popular resistance is to the risks of launching nuclear material, and that is no less for RTGs than for "real" reactors.

Nobody would be all that upset about launching an unfueled reactor, since that is basically just a collection of pumps and turbines not fundamentally different from anything we already shoot up. You could/should even launch the fuel and reactor in different rockets, so that you have more mass budget for wrapping up the fuel rods extra safely.

[perl4ever]

I think you're assuming a false premise, that everything nuclear in space is an RTG.

It's always possible I've been reading misinformation, but allegedly the major source of radioactive debris in orbit is defunct nuclear reactors that collided with something, and they also interfere with gamma-ray observations.

So if it is indeed true there are many satellites powered by reactors, it couldn't be obscure, many people must be aware.

[bserge]

I was being sarcastic. I mean ffs, the risk averseness has reached ridiculous levels.

[perl4ever]

AFAIK, it's been done, though. Not RTGs, actual reactors. They've been launched into orbit, deorbited and disintegrated in the atmosphere, and blown up in orbit spreading radioactive debris there.

Not one or two launches, but dozens. So there definitely is a risk, but it was once considered acceptable.

[adrianN]

Yes there are very good reasons not to put 10000 nukes on a ship and try to launch it. But it would be extremely cool to have manned missions to the gas giants and to send probes to nearby stars. I don't see how that will be possible without nuclear propulsion.

[robbedpeter]

Asteroid mining first - we will need processing and refinement infrastructure in space, to start building facilities that aren't in earth orbit, so they don't pose radioactive threats. It's thought that there is a lot of uranium and other nuclear fuels available in asteroids throughout the solar system.

Once asteroid mining kicks off, all sorts of possibilities open up that are overly expensive or dangerous for earth based enterprises.

[ianai]

Totally. I wonder about turning larger asteroid(s) into colonies/ships themselves. There’s one large one that already orbits between mars and the outer planets with a sizable radius. I wonder about hollowing it out and building essentially a large city in its interior.

Edit-I think it’s 1036 Ganymed.

[robbedpeter]

Mi pensa da beltalowda gonya fo tenye tugut liviting ere da belte!

We just need to crack longevity, space elevators, and asteroid mining. A lot of the engineering for in system spaceflight is engineered already.

With ever improving automation, belt mining probably won't ever be a human occupation in the way 20th century sci-fi envisioned, but living in space is looking like it will be very safe. We'll need lots of water shielding, massive engines and this massive ships, and deliberate regimented exercise and medical monitoring. We'll have to incorporate massive redundancies in environment and nutrition and waste processing, so long term high output nuclear will likely be the only option.

I'm excited to see the birth of space mining in the next decade or three.

[Valgrim]

I'd like to share an interesting read about the prospect of a nuclear-powered Starship. (http://toughsf.blogspot.com/2021/10/nuclear-conversion-for-s...)

Basically, it's not much about safety, it's also that the benefits of nuclear are marginal compared to what the Starship is already capable of, and in many mission configurations, it's actually worse.

[mrfusion]

There are lots of ways to protect the fuel. And beyond that you can launch over the ocean on a day the winds are blowing out to sea and completely protect populated areas.