[GlenTheMachine]

This is a very cool technology, but frankly I have a hard time imagining that it will see much use. NASA sees public protests and scare mongering whenever it tries to fly an RTG, which is based in the radioactive decay of (usually) plutonium, and does not use a nuclear chain reaction. They did fly one on Mars Science Lab, because it was the only way to get enough power for the rover. But it takes a PR hit every time it does so. RTGs are therefore only used when no other technology will work.

It think it's likely that the public relations nightmare NASA would have to go through to fly an actual reactor will be through the roof.

[andygates]

They used to get protests back when Galileo launched, but I don't recall any for Curiosity. There's the soothing effect over time of a known technology not screwing up.

Kilopower is safer, because it would launch inert, and it avoids Pu so any failures would be less toxic.

Downplaying the usefulness of a technology because of imaginary protesters isn't very helpful.

[lholden]

I don't think New Horizons received any protestors either.

[InclinedPlane]

It did: https://www.space.com/1929-nasa-pluto-mission-draws-dozen-pr...

(Not many, but more than zero.)

[JumpCrisscross]

Has anyone studied these protesters? My off-the-cuff sense is they’re mostly older environmentalists.

[sp332]

It's because sometimes a rocket explodes on the launch pad or a few seconds later, and it could spread radiactive material over a very wide area.

[rwcarlsen]

The half-life of fuel for these reactors is very long - over 100,000 years. So for all practical biological effects they are basically stable. If it exploded before it was activated (far into space), it would be about the same danger to people and the environment as the rest of the exploding metal the rocket was made of.

[bildung]

The half-life of the currently used fuel (Plutonium 238) is 87 years.

[Filligree]

The article is about a reactor that does not use plutonium.

[bildung]

Yeah, but this subthread is about protest reasons :) The reactor in the article (and the half-life of it's fuel) can't be the reason people are protesting.

[freeone3000]

Pretty much any uncontrolled explosion propels highly toxic material over a large area (rocket fuel is not lickable). I don't see how alpha radiation is inherently worse than hydrazine.

[zoe1337]

For that case there are launch escape systems typically used for crewed missions.

[ethbro]

The alternatives still seem worse.

[jlebrech]

they should be indoctrinating kids at school that nuclear is safe, rather than other "stuff" they tell them nowadays

[TeMPOraL]

Totally. You're probably catching downvotes from people offended by "indoctrination", but a) indoctrination is what schools do, that's their purpose, and b) nuclear is actually pretty safe.

I agree with the sentiment. Anti-science sentiments proliferate partly because science doesn't spend much on public outreach, especially compared to people who want to make a buck off scaring others about new technologies. NASA has been doing more and more PR work over the past few years, and that's great - but IMO in this case, they really need to get someone who looks and sounds confident, and who would go on national TV and say "Yes, we are totally sending a nuclear reactor to space, why wouldn't we?".

[7952]

I don't think people respond well to this kind of objective reasoning, it just doesn't work very well as an argument. At worse it can sound like you are calling them dumb. We need to explain the benefits, and why they are worth a tiny amount of risk. And accept that sceticism and concern are exactly what an intelligent layman should be exhibiting. Wondering if the thing is going to explode and cause cancer is a perfectly legitimate question to ask. To pursuade people you need to engage with them on an emotional level, not just bash them dismissively.

[TeMPOraL]

I agree. I didn't mean bashing people, just addressing some of the more irrational worries confidently as non-issues.

The way I feel it, engaging with irrationality legitimizes it. You don't want to do that too much. If you bend over yourself to explain that people really don't need to worry, it'll only make them feel that there is something to fear.

What I want to suggest is engaging with people on an emotional level, but projecting confidence while doing so.

[matt4077]

In your zeal to defend nuclear energy, you're come around full circle, defending something indefensible, with arguments far removed from actual science.

Nuclear energy may be safe, if done under near-perfect condition, with extremely large budgets to understand risks, and plans to mitigate incidents. There is truth to the argument that nuclear power saves lives compared to coal power.

But nuclear power isn't inherently safe. It is, by its very nature, extremely dangerous. Actual nuclear scientists understand that. See, for example, Feynman's work on nuclear safety during the Manhattan project.

Strapping a nuclear reactor to a rocket is almost by definition a dirty bomb. Depending on the height and mode of an eventual launch failure, the result could be anything from Tchernobyl to a less-dramatic yet more deadly dispersal of nuclear material in the upper atmosphere.

The dose-response relationship of radiation exposure is largely linear, meaning the latter event might just increase your risk of brain cancer by 0.005%. Yes, you may consider it negligible. But statistically, it would kill half a million people.

To blithely state that "nuclear is safe, hoho, why shouldn't we strap Plutonium to a rocket, you environmental nincompoops" has nothing to do with science, and gives science a bad name. Maybe NASA could come up with a way to protect a reactor during a missile launch. But it wouldn't be easy, and saying "why wouldn't we?" on TV would not inspire confidence in their abilities, but doubts in their sanity. The right thing to say on TV is "We're sending a reactor into space, and here are the mechanisms we've come up with to make it safe..."

[TeMPOraL]

I wasn't aiming for the full pro-nuclear argument in a single comment, because it's a well-trodden road. Nuclear safety issues have been discussed ad nauseam here and elsewhere.

But maybe I should have stated my main assumption explicitly: people at NASA know what they're doing. They're not incompetent morons, they can do the math. They already have absurd amounts of procedures in place to ensure a launch failure doesn't hurt anyone. They're not just trying to strap a bunch of random nuclear isotopes on a rocket and hope for the best.

> Strapping a nuclear reactor to a rocket is almost by definition a dirty bomb.

No, it isn't. A dirty bomb is meant to create a large-scale radioactive contamination that's dangerous to humans, and U-235 is probably the last thing you'd like to put in it. It's an alpha emitter with a half-life so long it doesn't matter, so the only effect you'd get is heavy metal poisoning.

(That's beyond the fact that dirty bombs are speculative devices, and from what I read, they actually turned out not to be a real issue in practice.)

> Depending on the height and mode of an eventual launch failure, the result could be anything from Tchernobyl to a less-dramatic yet more deadly dispersal of nuclear material in the upper atmosphere.

That's the kind of thinking that I suggest we need to fight with a serious public outreach effort. Chernobyl was a total clusterfuck, but the only connection between it and the NASA project is the word "nuclear" in newspaper headlines. Chernobyl was an active reactor, and its explosion contaminated the area with reaction products that had very low half-life and underwent beta and gamma decay, making them really dangerous, unlike plain U-235.

> To blithely state that "nuclear is safe, hoho, why shouldn't we strap Plutonium to a rocket, you environmental nincompoops" has nothing to do with science, and gives science a bad name.

I'm not saying that. I'm saying that there's so much baseless fear around nuclear energy as a whole, that it's high time we stopped treating it as reasonable. And right now, the biggest danger around nuclear energy is the cost in lives of it not being used instead of fossil fuels.

[gambiting]

"Depending on the height and mode of an eventual launch failure, the result could be anything from Tchernobyl to a less-dramatic yet more deadly dispersal of nuclear material in the upper atmosphere."

The thing about this reactor is that it doesn't work until you switch it on - so in case of an explosion you are spreading a near-stable isotope that you could handle without any health risks. Chernobyl doesn't compare, because the ashes were spreading isotopes produced as a result of operating the reactor, and are simply not present here until the reactor is actually switched on.

[_0w8t]

"nuclear is safe/unsafe" is meaningless unless we compare that with other technologies. Nuclear, despite all its nasty problems, is safer than many other technologies that are in wide use.

Consider coal electricity. It kills much more people globally than potential harm from space probes with nuclear engine blowing up in atmosphere periodically. Yet we continue to burn coal.

Or consider bio-engineering. We mess with cells without understand how they work. And since cells are self-replicating, we have a potential of quickly making the whole planet permanently unsuitable for human life. Compared with that the total risk of nuclear is bounded even after accounting for a possibility of a large-scale global nuclear war. Yet protests against, say, GMO are rather weak compared with protests against nuclear energy.

[acidburnNSA]

The models we use to guess dose vsm health are linear with no threshold and we chose this to be conservative in lieu of real low dose data. Since then there has been zero conclusive evidence that low dose radiation causes any harm at all. The people who live in very high natural background level areas have never been shown to have higher incidence of anything that could be linked to the radiation. The body has error correcting repair mehcanisms that can handle a lot.

[jlebrech]

the nuclear reactors you are so afraid of were designed in the 60s and haven't gone through stringent computer simulations, nowadays you have 100s of companies test every single part that will end up in a working reactor, it's come a long way.

[elihu]

Nuclear isn't inherently safe, though. It can be safe if the people do their jobs correctly. Whether you believe it is safe really comes down to whether you believe that regulatory agencies can provide adequate oversight to prevent people from cutting corners, making bad risk/benefit trade-offs, or sweeping problems under the rug to protect their jobs. That's more of a political problem than a technical one, and I don't really blame people for being skeptical that oversight in real-world scenarios is 100% effective.

[maxxxxx]

"RTGs are therefore only used when no other technology will work."

I think this is a good thing. And it seems they can use them if nothing else works.

[nine_k]

"Good" as in "extra expense and possibly lesser capabilities", I suppose.

[hutzlibu]

And the bigger chance of failure like Rosetta could not send anymore, because the solar panels were blocked ...