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It's about time. Engineering decisions shouldn't be made based of irrational fears of general population. If nuclear power plant is best option for space mission we should use it.



I agree with your sentiment but let's face it, sending humans to Mars is as much PR as it is scientific research (maybe even more). Look how we ended up on the moon in the first place. If NASA wants to get the funding it has to make it as marketable as possible.

If there's a big push back from the general population it will be hard to convince the politicians to invest billions in an unpopular project with no short-term dividends.


On a related note, I very much like the fact that "The Martian" movie uses RTG as a life saving device and the best car climate control ever. It helps with the public perception that it's not that dangerous.


Generally I agree with you, but I don't know if it's wise to promote the unintended use of a device by a fictional character as a last hope in a dire survival situation as the bar for what's "safe". Regardless of whether it's actually safe, showing me it's safe enough to sit near in a situation where one would probably die anyway isn't exactly comforting.


Well, NORAD guards used to keep warm by standing in front of the dishes. I vaguely recall that some also figured out that doing so temporarily reduced their sperm count ;)


Culture is better at transmitting ideas and changing perceptions than elitist blowhards are.


I would say, given the state of politics and the general attitude to the climate and natural resources, our first priority should be colonising another planet. Putting some scientists on Mars for a few years is step 1 in that very important insurance scheme!


I don't know if I agree. Creating a self-sustainable colony on Mars will take a very long time and even if we manage to do it can we really afford to "lose" the earth? Mars is an inhospitable hell for humans and practical terraforming technology is still in the realm of science fiction. Maybe if we manage to destroy earth completely out of selfishness and hate we don't really deserve to spread the virus throughout the galaxy?

And running away won't solve our problems. How long until our current earthly political and environmental issues are reproduced on Mars? We have "human" issues, not "earth" issues, simply moving the problem is not a solution. If we can't sustain our development in a civilized manner on a lush and hospitable planet I don't think we'll fare much better on Dune.

Not that I'm against colonizing Mars but I'd prefer if we did it out of a shared dream of a trans-planetary humanity rather than out of fear of self-destruction.


Very unlikely that we could do anything on Earth that would make Mars look like a better place to live.


"Very unlikely that we could do anything on Earth that would make Mars look like a better place to live. "

Humanity: Hold my beer....


Runaway global warming or global thermonuclear war will still leave many parts of the Earth far more habitable then Mars.

Even if the biosphere were to go to hell, it would still have an atmosphere, and a magnetic field. Fantasists have wildly impractical ideas for fixing the former on Mars, but nothing for the latter.


There is a solution to both, and it's not impractical: https://news.ycombinator.com/item?id=13796364


The universe is full of planet destroying events, why single ourselves out and say we are a virus?

Sure, we need to be better stewards of our environment, but I fail to see how our species is inherently worse then a meteor destroying a planet.


>If we can't sustain our development in a civilized manner on a lush and hospitable planet I don't think we'll fare much better on Dune.

Arrakis at least had an oxygen and nitrogen rich atmosphere.


And a valuable natural resource to make the whole colonization thing worth it.


Well, heh, when you look at the events that unfold afterwards, "worth it" is debatable.


True. I didn't read that series far after the first book, so I will not presume to debate you on that. :)


I agree about self-created problems, but what about annihilation through any other "natural" mass extinction event? I'd argue that to be a good motivating factor.


That's an interesting proposition, but how realistic is it really?

If we're talking about something like a huge asteroid colliding with the earth and/or a huge volcanic episode that would trigger a mass instinction, wouldn't the pale blue dot still be more hospitable than Mars? We have access to technology the dinosaurs didn't have, our chances of survival would probably be much better overall.

Even in case of man-made devastation, such as mass pollution or a nuclear winter I think it's safe to assume that Earth would still be more habitable than Mars.

How about something even more destructive? Maybe something like a gamma ray burst? Well then Mars is probably not far away to put it out of harm's way, although maybe they would be more likely to be unaffected by it if it hit the other side of the planet due to its very thin atmosphere? I'm not sure.


If an event happened that caused the Earth's atmosphere to not be breatheable in a number of hours, would anyone survive? We may have the technology but do there already exist any artificial independent self-sustaining human habitats on Earth that would survive? We could try to build such habitats now -- it would probably be cheaper than going to Mars -- but I think we would have trouble forcing ourselves to spend the money and effort on it and have trouble keeping it honest (avoiding any cheats where it's mostly independent but still dependent on the Earth's ecosystem for some specific uses) without a separate goal (being on another planet) and a hard forcing factor (an environment that doesn't allow any cheats).


The fear of self-destruction (or phrased as its complement, the drive for survival) is one of the most potent motivators that humans have.

The argument could be made that Martian humans would be supremely motivated to move the environmental parameters there toward a survivable state for lightly-outfitted humans.

Contrast this with Earth, where space exploration is a four-order or fifth-order concern for most people, and long-term environmental issues are treated as abstract exercises in reducing economic externalities. This is because Earthlings have (mostly) had it easy. We're biologically evolved and culturally adapted to survive here, and thus don't have a strong intrinsic motivation (yet) to maintain the long-term health of the biosphere.


If we could terraform a planet as barren as Mars, wouldn't fixing earth be significantly easier?


No, because Earth is still covered with humans that can obstruct your plan for irrational reasons.


Yes, which is exactly why we should terraform Mars: as a test run of a severe-case rebuilding scenario. If we can handle Mars even at its best (let alone its worst), then we can handle Earth in all but the most catastrophic events.

I personally feel that having a "fallback" in case something literally Earth shattering happens is compelling enough a reason to colonize other bodies in our solar system, Mars included.


I just dont get it why we have to go down another gravity well.. why is it such a unpopular idea, to put some tents up inside a asteroid?


I don't disagree. Ceres ain't that much further, and it's literally a giant ball of water and hydrocarbons.

That said, it's possible that even Mars' relatively low gravity is enough to stave off the health problems associated with prolonged microgravity/freefall, so that might be good motivation. If there's some lower bound on how high g needs to be in order for our bones to not become brittle, and Mars is above it while - say - the Moon is below it - then Mars is really the only option besides the moons of the gas/ice giants (and their respectively-giant gravity wells) or Venus (with its Earth-like gravity well and its hellscape of a surface).

So there's another scientific motivation: to measure the effects of low but existing gravity on human health.


Yes, it would be.


The biggest problem to fixing earth is the people with politics that fly in the face of reality. Mars Doesn't have republicans, so I think it would be easier to terraform than earth.


Unless you're building better humans, we're going to have the exact same political problems on Mars that we do on Earth. Except in an environment where any small thing going wrong has the potential to kill everyone.


>Unless you're building better humans, we're going to have the exact same political problems on Mars that we do on Earth.

No, not immediately.

This isn't much different from other colonization missions in human history: humans from one place got sick of the people living there, and went somewhere (relatively) uninhabited so they could live the way they wanted without the political problems they had back home. Eventually, there were new political problems of course, but that took generations; for the initial travelers, it was a sensible move. And the political problems that came were likely different, as so much time had passed.


Doesn't that already describe Earth?

We could accidentally fire nukes, accidentally let a GM smallpox strain out, accidentally start WW3, we could do so much as it is. That is beside the point anyway.

Presumably the first people to go to Mars are going to be vetted for some level of education and skill. This will likely prevent the fear mongering, demagoguery and other forms of lying that allow some successful politicians argue against singularly true facts, at least for a little while. Likely until the mars colony is self sufficient.

Even then it seems unlikely you will get an anti-global warming lobby on Mars, because it is good for every business (presuming breathable air is government utility/service).


I agree. Though we might disagree on where legitimate concerns end and irrational fears start. It is also non-trivial to decide (and argue around) what a 'best option' is without defining a scale of what 'good' and 'bad' would be, and what factors are considered in that scale, and which ones are left out.


Can we start by agreeing on whether or not we care about a nuclear reactor going "pop" on mars pre-colonisation?

Because, you know, there's a chunk of me that thinks we can be less risk averse in trying to do things on an uninhabited planet. Nuclear meltdown is pretty awful on earth, on Mars I don't see it with the same fear.

I also feel like this is not dissimilar from dumping rubbish in the neighbours yard because who cares it's not mine but on a planetary scale. Which seems bad but I want to rationalise it away and say "but this is different".


The concern was never about a nuclear reactor having a failure mode on Mars. It was about the rocket carrying the nuke having a failure mode and spewing radioactive fuel over central Florida.


Before a rector is turned on the inside of it isn't particularly radioactive. In order to last from the creation of the solar system to the present day uranium had to decay very slowly when not in a critical mass, specifically U235 has a half life of 700 million years. So it's really the radiation of uranium that you have to worry about if you find yourself in a room with a hunk of it but the toxicity. Still, people made cookware with uranium in the glaze and managed to avoid killing people.

Now, as soon as you turn the reactor on you start turning the relatively safe U235 into all sorts of nasty things with half lives that are much, much shorter than 700 million years like strontium 90 with a half life of 30 years. That stuff is indeed horrible and getting it spread over Florida would be a disaster. But the solution is to make sure you don't turn the reactor on until it's safely in orbit.

That makes them much safer than the RTGs we've been using to power space probes far away from the sun previously. Because the P238 isn't in a critical mass it has to be a synthetic isotope with a low half life in order to generate enough heat to power a spacecraft when it's outside a reactor and would be quite deadly if you interacted with it without shielding.


Not saying it was unfounded fear (I'm very pro space nuclear power), just pointing out what the actual contention is. People have an adverse reaction to anything with the word "nuclear" on it, even more so when it is put on top of a half million pounds of propellant and lit with a non-negligible failure rate.

The reality though is that failure of the rocket doesn't mean the reactor or fuel is vaporized and thrown to the wind. It's possible to construct the payload fairing to survive sudden, rapid disassembly and crash land intact off the Florida coast for recovery.


It's not just the word.

A nuclear-armed intercontinental ballistic missile is visually identical to a launch rocket carrying a peaceful payload to LEO. The neural association between "nuclear missile" and "rocket with nuclear reactor payload" is very strong.

It doesn't matter how many facts you throw at it. In the mind of the public, all launches have the possibility to result in another Apollo 1 or STS-51-L (Challenger) or STS-107 (Columbia). Every "nuke" is the Castle Bravo test. Every reactor is Chernobyl. And the public generally is terrible at risk assessment and actuarial math.

You could actually make the launch safer than an afternoon stroll on a Florida golf course, but no one is going to lie down in front of your golf cart screaming, "lightning strike!" or "angry gator!" or even "cardiac infarction!" or "terrorists!"

People may have no problem at all if you just call it "an NCG power plant" (for neutron-cascade generator) and say the details are classified for security reasons--that "security" being the type associated with a toddler's blanket.


Sure it's not in critical mass or particularly radioactive, but Plutonium is toxic...


NASA's Kilopower design uses enriched uranium fuel, and with such a small reactor it won't be much uranium.


I'd expect that part of the reason they use uranium instead of plutonium is exactly to make sure the reactor is safe in the event of a rocket failure.


I expect it to be because there isn't much plutonium left [1].

[1]: http://www.popsci.com/plutonium-238-is-produced-in-america-f...


So is hydrazine and dinitrogen tetroxide is also all kinds of fun. Heavy metal toxicity is manageable.


> uninhabited planet

By humans. By other life-forms is yet to be proven one way or another. There is already discussion of treaties to prevent contamination of any Mars biosphere by human missions there.

Also: what about the future? There's no point in sending a nuclear reactor to Mars if a future colonisation mission can't go ahead because the reactor has melted down...

Solar irradiance is approximately 50% less than on Earth. PV with high efficiency modules (the same ones they use on satellites) is also viable. I wonder if anyone has run the numbers on the cost of shipping a reactor Vs. the cost of shipping a football field of PV modules there.


Installing/laying out a football field of modules sounds rather tricky, as does keeping them clean (mars is dusty and windy).

I assume the nuclear reactor would be a pretty much "sealed unit" which just needs to get rid of a lot of heat. There is no reliable water/evaporative cooling on mars, nor is the atmosphere thick enough for fans etc. to be effective. Instead it will need huge thermally emissive panels. For them to be effective, they need to be very hot.


Dumping heat into the ground is another option. But, generally keeping things warm is going to be a larger issue than keeping things cool unless they are producing crazy amounts of power. Further, the atmosphere might only be 1% of earth's but when the temperate averages -60C you can still use it to passively dump heat without needing vast radiators.


It's solar plus batteries which have been used for rovers for a long time, but simply weigh more and have a relatively short lifespan. Especially when you consider how useful 'waste' heat is on a planet that gets that cold.

As to contamination, it's a planet we did not abandon earth when Chernobyl melted down. Worst case nobody goes within 100 miles of it for a few decades. But frankly people are unlikely to go to 99% of Mars anytime soon and can't walk outside without significant protection anyway.


Are the nuclear reactors we're transporting to Mars safe in case of rocket explosion? Because rocket explosions/failures happen way more often than Fukushima type situations.


Yes, it's been much tested. They aren't operational until they make orbit.


Irrational fears? What are the chances of the rocket launcher blowing up with the reactor? How would we compute the fallout range as a function of altitude of the blast?


Irrational because a uranium fission reactor contains very little radioactivity before you start running it.


Do you know how much nuclear material we've launched into space? Hint: a lot.


So that's the beauty of it being a nuclear reactor as opposed to an radioisotopic thermoelectric generator. An RTG will be very radioactive at the time of launch, a nuclear reactor need not be. As long as one doesn't start the reactor before launch by removing the fuel rods, it's practically inert. One might even start the reactor only when the probe is confirmed to be on an escape trajectory from Earth to avoid the possibility of contamination.


According to Wikipedia, "some granites" contain 10 to 20 ppm of uranium, and the density of granite is about 2.65 g/cm^3. If a rocket contains 10t of pure uranium, that is the same amount of uranium in a cube made of uranium-rich (20 ppm) granite, each side about 57m long.

Now imagine how many such cubes would fit inside your favorite mountain.


Please at least tape it! A nuclear reactor mounted on a gigantic explosive sounds like a stupid idea once you count this risk, but even if we did it, would it be among the most stupid things we did?


I don't thinnk it was the fear of the general population, because what influence do we have on dangerous endeavors? If the scientist can do it safely, they could just do it.

It must have something to with the state of technology and not being able to do it safe until now.


I disagree. Nuclear reactors have been very safe for a long time now, but between high profile incidents with old reactors, the link with nuclear weapons, and misinformation, the public perception is that they are unsafe.


"very safe" might be true (your interpretation of 'very' might vary), but it is a low chance/high price kind of thing. I live in Bavaria, and hunters here still need to take precautions due to Chernobyl, some 31 years later.


It's very safe if you don't disable safety systems put in place (like it was explicitly done in Chernobyl to do dangerous experiments, even though they labeled it as "routine tests"). And if you don't ignore many warnings given in the industry (like TEPCO ignoring many recommendations of raising their tsunami protection walls many years before the catastrophe, like other plants closer to the epicenter that were unaffected).

So the chance is much lower than people think, if plans have measures to avoid such corruptions. And that's not counting the many safer designs we have nowadays. Many plants today don't even need backup electricity to automatically shut down by themselves.


I fully agree that newer designs are safer, but ignoring the human factor in the equation is IMO not very reasonable. Without the human factor, driving a car is very safe. That argument is valid, but it doesn't reflect reality.


Good engineers take the human factor into account and include backups in their designs to handle failure modes caused by the human factor.

What they can't do is work around politics or budgetary constraints which force trade-offs between safety and cost. Anything can be made as safe as necessary, if you're willing to pay for the redundancies.

When it comes to reactors on Earth, a very large proportion of the budget is diverted to bureaucratic paperwork, lobbying, and PR, which could instead be used to pay for additional safety measures.


There are some "human factor" problems that engineers cannot and should not be expected to resolve.

I mean, how can someone design a communist-proof nuclear reactor?


Make them pay to get in?


Wouldn't work. They know how to steal and can even make fiat currency outside of the free market context.

Not a bad idea though.


Sure, but that was a) 31 years ago, b) a reactor built without the safety standards we have now, and c) a reactor operated without the safety standards we have now.

As far as I understand, making a reactor built in the last 25 years go 'wrong' in any way like that is very difficult, and would take much more than negligence or incompetence.

Fukushima is an example of this – the reactor that had issues was over 50 years old, but all the modern ones were fine.


It's always been political, both in terms of the relative "scariness" of nuclear technology after Hiroshima and Nagasaki, as well as the costs of space programs.

Most of the space flight technologies using nuclear power were devised for manned flights beyond Earth's gravitational influence, and were on the drawing boards as early as the fifties. Once America successfully landed on the moon and the Soviets gave up, there was immense political pressure to scale back the US space program. With the Space Race won, it was harder to justify the costs of manned interplanetary spaceflight, so a lot of more exotic (read: expensive) plans were shelved. This included more than a couple nuclear propulsion ideas for spacecraft, including one for a nuclear thermal rocket that had been successfully prototyped in the lab and was ready for an actual launch.

Lots of stuff we could have done and could be doing in space if there was money for it.




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