NASA Revives Plan to Put Nuclear Reactors on Mars | Hacker News Reader

NASA Revives Plan to Put Nuclear Reactors on Mars

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204 pointscurtis153 comments

Before we can consider seeding terrestrial stations on Mars, we should consider seeding a communications net around Mars. Once we have a half dozen satellites circling Mars, we can start stable comms from the surface to orbit to Earth. It may take 10-20 minutes (for a signal to be received), but the communication is the essential piece here.

I'd also consider putting satellites in Earth and Mars lagrange L3, L4, and L5. It's the start of a solar system based internet, even if it is rudimentary. Think of this as a store-and-forward network where signals may be too weak for Earth to pick up, but can hit Jupiter L5 to Mars planet, to Earth L3.

And greetings, all, BTW.

Bulding the Network is the best part about KSP, right?

Pretty sure this reason in specific is why SpaceX accepted the 1 billion USD investment from Google Ventures for their satellite internet constellation project in Seattle. If Musk's endgame plan is a serious Mars colony, there needs to be both location and communication over the entire planet (of mars). There also needs to be bidirectional communication with Earth. An orbiting constellation makes sense to do this.

https://www.nytimes.com/2015/01/21/technology/google-makes-1...

The important part of mars colonization is being able to produce 100% of all needed goods (from food to CPU's) on the surface of mars, not covering the planet with people. Really 2-3 redundant geosynchronous satellites on mars should be plenty for a very long time.

Musk wants satellite internet as it lets Space X lower cost per launch by launching a lot of satellites.

> on the surface of mars

Why? Wouldn't it be easier to bootstrap by mining asteroids, and manufacturing in micro gravity, then dropping nearly finished goods onto the planet? That'd also allow you to use the same bootstrapping infrastructure for several surface sites.

Mining asteroids has a ton of issues even beyond the obvious cost and R&D problems. They are generally far from the sun so solar power is significantly less useful. You need to move a lot of bulk material which means heavy Delta V problems. Micro gravity means you can't have humans in the area for long without giant structures. Finally, economically resources are just not that scarce.

The delta V issues are more reasonable when you want stuff to end up in space. But, that's not an issue for a Mars colony. As to mining Mars's moon's they don't really have a lot of useful material that is not on Mars in the first place.

PS: Space X's slightly lower the cost to orbit actually makes Asteroid mining even less viable.

>They are generally far from the sun so solar power is significantly less useful.

No, they aren't. There's tons of asteroids in Earth-crossing orbits. And Mars-crossing orbits too. It'll be a long time before we use those up.

>You need to move a lot of bulk material which means heavy Delta V problems.

No, you don't. You process the ores near the asteroids; you don't have to ship it all to the point-of-use.

>Micro gravity means you can't have humans in the area for long without giant structures.

So what? You don't need a lot of humans there; this stuff needs to be automated (or at least remote-controlled). And artificial gravity doesn't need a giant structure; you can do it with a small structure on a tether.

>Finally, economically resources are just not that scarce.

That depends on what resources, and where you want them. If you want a lot of platinum, it's very scarce here on Earth, but mining one Earth-crossing asteroid could provide a huge amount of it relatively cheaply.

>As to mining Mars's moon's they don't really have a lot of useful material that is not on Mars in the first place.

How do you know that? Mars's moons are really just captured asteroids and likely have no geological relation to Mars at all.

Basically, if you can mine it on earth you can do the same on mars excluding organic compounds.

Anyway, back to your argument. Processing ore is not light weight. Total mass of asteroids inside earths orbit is actually surprisingly low relative to planetary manufacturing needs. Sure the asteroid belt is ~4% of the moons mass, but inner planets have mostly cleared their orbits.

Yea, there are KM sized objects, which might be rich in stuff we want. But consider, Bingham Canyon Mine for example is 0.6 miles deep and 2.5 miles wide and that's just for copper. And even if you processed it all you still need Delta V on 19 million tonnes of copper.

Look at a periodic table. Mines can only really provide you with that stuff. Now exclude the useless elements and the stuff and what's abundant and there really is not a huge niche for asteroid mining. Futher ateriods regularly impacted mars after it had a solid surface so all the same elements are there much like they are on earth.

So, you really need asteroid mining to stand on it's own independent of colonizing Mars.

PS: Artificial gravity only gets you part of the way to dealing with micro gravity You need life support, food, water etc. Spin all that stuff and you need an even stronger tether with a larger counter weight.

Luckily for us, a bunch of wealthy and influential people disagree with you and know more about this stuff than you do, and have started companies like Planetary Resources. All that stuff we're mining from the Earth's crust came from asteroids, not from the formation of the planet, and it's far better concentrated in asteroids than it is in the crust, so no, there really is a huge niche for asteroid mining or else there wouldn't be a lot of money put into exploring this. No, asteroids impacting Mars are going to have the same problem that they do on Earth: it reduces the concentration too much so you have to process a lot of dirt to get to the valuable ores; this isn't the case with asteroids.

>You need life support, food, water etc.

We figured all that stuff out ages ago. We can already recycle air and water and have been doing so on space stations for decades. Food can be supplied by resupply missions, and also grown on-site; it's not that hard. You're completely overstating the problem. If you think that running a small space station is somehow far harder than running a habitat on Mars (where you cannot control the gravity at all), which seems to be what you're implying here, you have no idea what you're talking about, and I think you're being intellectually dishonest to boot.

'Planetary Resources' is a scam. They get good PR by talking about space mining while working on something completely different.

To put things in perspective if we knew about a 1,000 ton 100% gold asteroid at say 1.2 AU, getting that to earth right now would cost more than it was worth. Add on top of that the need to refine stuff in space or send back less valuable material and it's a pipe dream until we get a lot better at spaceflight.

PS: You can increase the gravity of living spaces on mars 'easily' by rotating the habitat. Though we don't expect that to be necessary.

How would you rotate a habitat on Mars, without having a major engineering challenge due to the existing gravity? Citation needed. And how would it not be necessary? 1/3g gravity is surely not healthy for humans long-term. Citation needed.

How is Planetary Resources a scam? Citation needed.

Ahh, keep talking long enough and it's obvious you don't know what your talking about.

We can easily do 20g on earth: https://en.wikipedia.org/wiki/High-G_training

1g is much easier in mars gravity as you can simply tilt the chamber at an angle while spinning it. Training centrifuges generally have the chamber on a hinge so you automatically get the correct angle.

Now, sure you lose some energy to friction. But, not all that much further, we have a lot of experience dealing with very heavy rotating objects for decades. EX: Power plants.

A small centrifuge is not a viable place to have an entire colony to live in. Sure, you can stick someone in a high-g centrifuge by himself for a little while, but I'm talking about a habitat that people live indefinitely. Equating the two clearly shows you don't know what you're talking about.

> having a major engineering challenge due to the existing gravity?

Rotating a habitat is a hard problem in space or on a planet. But, Mars's is gravity would make the problem easier not harder. The atmosphere might be a problem, scale might be a problem etc etc, but gravity is not. Further, there may be little need for 24/7 1g, perhaps a tiny room to work out in is enough, perhaps you should sleep in 1g or perhaps 1/3 is enough for sleep etc.

But, again gravity is not the problem. And yes such a massive fundamental failure in understanding is a clear sign of incompetence.

Rotating something that size in Mars' gravity is far more difficult that rotating something in space. Clearly, you're far less competent than you think you are.

We literally already rotate large structures for amusement.

https://en.m.wikipedia.org/wiki/List_of_revolving_restaurant...

To be fair, they intentionally rotate slow enough as to have no perceivable g forces.

The example on that list that I had been to most recently is the Westin in Atlanta.

It's 57M in diameter and it's upper floor spins at once every 30 minutes. Plugging that into Mω²r, you end up with 0.0000354084g.

Not exactly the best example.

Why would you want to manufacture in microgravity? What are the practical advantages of this? I can't think of any, but I can think of a lot of disadvantages of this.

Also, a Mars colony would require millions of tonnes of raw materials. You can only get that in-situ.

I think the largest problem in orbital manufacturing is actually rejection of waste heat. Otherwise, being able to run robots in an oxygen-free environment and move around large masses without conveyors sounds pretty good.

It's also an environment full of cosmic rays, which requires hardening of all your electronics, an environment where fluids don't flow through pipes, an environment where dust and powders don't settle, an environment where conveyor belts don't work because things float off them...

Almost every single industrial process that we have relies on a constant, freely available, predictable, unidirectional acceleration of 9.8 m/s^2.

Imagine trying to build a twenty-tonne steel smelter that will function in orbit - I'm sure working with tonnes of molten steel that won't stay where you put it would be a breeze.

There's also the part where many of our industrial processes are extremely water-hungry. Any kind of space industries would require complete reclamation of all waste water, stream, etc - with a large cooling cycle, to boot. And heaven forbid if the process consumes nitrogen, oxygen, or hydrogen in any appreciable amounts - unlike on Earth, you can't synthesize them in space.

You're thinking of it the wrong way. The goal is not to transplant existing Earth manufacturing processes to orbit. That's currently impossible without a launch vehicle powered by nuclear bombs.

There is no 20 Mg steel smelter in orbit. The use cases are very different. First off, you're not starting with coke and iron ores and ending with flat carbon steel. Whatever you make is staying in orbit, to replace something that would otherwise have to be launched. You probably need to make 17-4 PH stainless steel, with synthetic thin-film silica surface coatings to prevent vacuum welding. And where is the raw material--iron, nickel, tantalum, chromium, etc.--coming from?

You can't just replace an existing industry with vertical conveyor belts 5 miles high and expect it to work.

Firstly, the raw materials: https://en.wikipedia.org/wiki/Mond_process , https://en.wikipedia.org/wiki/Carbonyl_metallurgy , https://en.wikipedia.org/wiki/Chemical_vapor_deposition .

You would likely be reacting powdered asteroid dust with CO + H2 (syngas), distilling the carbonyl vapors, and depositing nearly pure metals at higher temperature. The purified metals do not subsequently react with oxygen, because that is all kept bottled up for other purposes. Now you don't need the Bessemer process or oxygen converter process, because the iron is already pure, and also you don't have enough oxygen to waste on it. Since you're already using CVD in high vacuum to build up your ingot, you might as well just add the alloying elements and silica coating right there, on the asteroid, before you fling it to whatever orbit you want it to be in.

Metal carbonyl chemistry works at relatively low temperatures, below 250 degC. You don't have to worry about toxicity if you don't even have humans on site at the facility.

It's far cheaper to send people to asteroids than Mars. Even those in the belt. And they have trillions of tons of easily accessible raw materials.

> Before we can consider seeding terrestrial stations on Mars, we should consider seeding a communications net around Mars.

We already do.

> Once we have a half dozen satellites circling Mars...

We already have half a dozen active satellites circling Mars:

https://en.wikipedia.org/wiki/2001_Mars_Odyssey

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

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

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

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

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

All of these (including the European satellites) except the Indian MOM orbiter contain a communications relay radio (for relaying from Mars surface to Earth) provided by NASA: https://en.wikipedia.org/wiki/Electra_(radio)

We actually have quite a bit of infrastructure built up around Mars already. All these spacecraft are referred to as the "Mars fleet" (which is frakking awesome...).

>https://en.wikipedia.org/wiki/Electra_(radio)

>Data rates up to 1 Mbit/s

That's a bit of a problem. It only seems to be a relay for other spacecraft and small surface craft. Much more data will need to be exchanged between Earth/Mars when humans are involved (weather, video, entertainment, collected data, software, etc.)

You'd probably want several brand new satellites dedicated to communications for an initial colonial undertaking.

MRO does 6Mbit/s.

But indeed, NASA intends much higher bandwidth for future missions using laser communications.

SpaceX would likely use a variant of their constellation satellites which should be capable of multiple Gbit/s using laser communications.

If you think about the initial communications infrastructure around North America when Columbus set sail in the 15th century, we've got a leg up.

I realize it's not the same situation, not the same expectations, a different world than 500+ years ago, but real progress doesn't happen in a cleanroom.

Once humans get involved, putting up a better communications satellite fleet should be trivial by comparison. You could almost just toss some satellites out the airlock before you start aerobraking. Obviously it would take a little more thought than that, but it certainly wouldn't be the hard part of the whole deal.

1 Mbit/s is a problem? This communication network we're currently using started out at just 300 b/s, 3000x lower bandwidth. When speeds got up to 2.4 Kb/s, it really started to take off.

The bandwidth back than was more than adequate to handle a website like Hacker News, and the store-and-forward protocols that were developed back then to preserve bandwidth, like SMTP and NNTP, will probably come back into play for a Mars/Earth link. Any video would need to be highly compressed and low quality by today's standards, but in the 50s and 60s TV was far lower quality than it is today and served its purpose just fine. Audio recordings for voice messages likely would be just fine without any quality reduction.

You have to remember that the initial colonists are going to necessarily be a fairly independent bunch. They're not going to need, or care, to keep up with the latest shows, music, or social media. They'll be too busy with surviving, collecting and transmitting scientific data, and writing letters to their loved-ones back on Earth.

> I'd also consider satellutes in Earth/Mars lagrange L3, L4 and L5 (...) solar internet.

If there isn't already a patent on space strategies, it may be a good idea to create a patent agency. The first intergalactic agency.

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. 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.

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

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

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...

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.

> 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.

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.

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.

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.

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

>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 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.

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?

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.

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).

>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.

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.

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?

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

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

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?

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.

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.

I looked into some numbers on this, comparing theoretical costs of nuclear power with a solar PV solution on Mars.

Kilopower (NASA's research project for a Martian nuclear fission reactor, from the article): 7,200 kg for 40 kW. [1]

ISS solar arrays: 14,515 kg for ~100 kW in Earth orbit. [2] If we assume 40-50% Earth solar insolation on Martian surface, the ISS PV array probably isn't far off 40 kW output on Mars

Conclusions:

Nuclear reactor would have approx. 50% launch weight. SpaceX estimate $45/kg payload with a Falcon Heavy, so about $324K for Kilopower or ~$600K for the ISS arrays.

The build cost of the ISS arrays was around $300 million (space PV is way more expensive than terrestrial). The development and test costs of Kilopower is around $15 million; build cost of final units is unknown.

You would have to automate and/or remotely control all of the nuclear power plant operations. Dust storms would be a challenge to a PV solution, though not insurmountable.

They actually look very comparable. Nuclear has an edge due to it weighing half as much as the equivalent PV generation system. I think there is definitely value to a simpler system that's more decentralized... but that's harder to quantify.

Edit: people noted I forgot to factor in batteries. 40 kW = 480 kWh per 12 hours. 1 Tesla PowerPack = 220 kWh @ 50 kW. Let's assume a worst case that the base needs the same electrical power during the night as it does in the day, so we need around 5 PowerPacks to get us through each night. 1 PowerPack weighs 1,622 kg, 5 = 8,110 kg. Wow, we need another Falcon Heavy trip just to bring us enough batteries for 1 night! Let's not mention those dust storms that can last for a month or so...

Now nuclear looks much better... and that has its own complexities. Colonising Mars is going to be very hard. :)

[1] https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201600...

[2] https://www.nasa.gov/mission_pages/station/structure/element...

A robotic rover can afford to shut down during the night but humans aren't able to do that. So you need to average out the power generated over the day night cycle and add mass for enough batteries to store daytime power for use at night. Last I did the calculations that roughly doubled the weight. So more like a factor of 8 than 2. But still, power generation won't be the majority of the mission weight so it's not a slam dunk.

On the moon it would be. Half-month long nights mean you'd need a lot more batteries if you're making a permanent settlement and aren't at one of those spots on the south pole where you can always see the sun traveling along the horizon.

EDIT:

I think solar panels have gotten a lot lighter since the ISS went up and when I last did the math nuclear and solar were a lot closer.

You are correct. I updated my post with some battery calculations. Only enough battery energy for one night adds another Falcon Heavy of payload. The dust storms will be a huge intermittency problem too.

Maybe you forgot to account for batteries?

Better windmills :D This green energy hoax barely sustains communities on earth, why would sane someone risk on Mars? Mission needs reliability - we have nuclear power sources reliably working for decades, powering bigger things than calculator.

Can you explain what you mean by "green energy hoax [that] barely sustains communities on earth"?

Renewables are part of having a diverse power grid and because of the investment needed they are situated in areas with consistent/reliable wind/solar radiation.

I drive past the massive wind farms of Minnesota and he Dakota's regularly - they are almost always generating electricity. My understanding is that the US has significant potential renewable energy reserves.

Edit. Wikipedia suggests that about 14% of the US grid is currently renewables (https://en.m.wikipedia.org/wiki/Renewable_energy_in_the_Unit...) - that seems far from "barely sustaining".

The map of potential for wind alone suggests great potential - https://en.m.wikipedia.org/wiki/File:Wind_power_potential_ma...

Thanks for this concise comparison. As others have noted, you also need to account for batteries, and battery churn. When the batteries need to be replaced, you have quite a bit of additional payload that needs to be delivered. I am sure that nuclear fuel rods (or pellets, or whatever fuel type they are using) will be dramatically lighter and easier to transport.

Dust will need to be cleaned off of the panels daily, which adds further expense associated with dedicated external missions to the array of panels.

Most of the ancillary considerations weigh in favor of the nuclear option.

>The build cost of the ISS arrays was around $300 million (space PV is way more expensive than terrestrial).

That was 20 years ago, on a government contract, for panels that must survive the rigors of actual space.

Panel manufacturing costs have dropped almost 10x since then, and the environment (assumed under the protection of martian atmosphere) which they will operate will be far less extreme than Earth orbit, necessitating less expensive materials. I'm not so sure your numbers account for this.

Good points. They do need to be tough enough to withstand Martian dust storms, but apparently they aren't as bad as they look due to the low atmospheric pressure. I read the biggest problem is cleaning the dust off them.

Space applications use single crystal GaAs (Gallium arsenide) process instead of wide spread c-Si (Crystalline silicon, currently usually multi-Si), due to their superior performance and weight.

Process of producing c-Si panels has become a lot cheaper but this doesn't apply to GaAs process.

The International Space Station's solar array is crystalline silicon:

https://www.nasa.gov/mission_pages/station/structure/element...

Space applications are now mostly using triple-junction cells with GaAs as one of the layers. Spectrolab, Azur Space, and SolAero's product lines are dominated by triple-junction cells. Azur Space also still sells space-qualified silicon cells (lower efficiency and much lower radiation tolerance, but cheaper):

http://www.azurspace.com/images/pdfs/0002162-00-03_DB_SIA.pd...

The Martian radiation environment is mild enough that crystalline silicon might still be competitive if you needed large stationary arrays. But on the Martian surface, where you can't rely on near-constant sunlight, nuclear is going to be tough to beat. (Orbiters are a much better match with solar.)

ISS solar arrays produce more power than that, plus they're literally from the 1980s. We have far more efficient and lower mass designs.

You should use Ultraflex or similar as a standard. Instead of the ~7W/kg you used for ISS arrays at Earth orbit, you'll get ~150W/kg at Earth orbit:

https://www.orbitalatk.com/space-systems/space-components/so...

We have commercial satellites that also use much cheaper arrays with much higher efficiency.

Using 30 year old solar tech with a very mass-inefficient design is putting your thumb on the scale of such a comparison.

I like kilopower and am a fan (it really helps for super deep space missions that currently have to rely on the tiny amount of Plutonium-238 we have and can make), but we're going to use a LOT of solar power on Mars just as we do today.

Wow, nice, thanks for the information. I find this stuff fascinating! Do you have any further reading?

How will they convert heat into electricity? On earth you have plenty of water as a good medium for the heat and a thick atmosphere that serves as the heatsink. On mars you have neither.

Sterling-cycle generator, utilising heat pipes, based on this study (PDF):

http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lare...

Tracked via Wikipedia, which has a brief article:

https://en.m.wikipedia.org/wiki/Kilopower

Non-mobile link:

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

https://en.m.wikipedia.org/wiki/Thermophotovoltaic

There are a few obvious things that need to be stated in order for the public to prepare for a manned Mars mission.

The fact that we're going to have to use some sort of atomic batteries is one of them. Another is that we can't search the entire planet for life before we go visit. It's impossible to disprove a negative.

My preference would be to see every piece of gear have an integrated solid-state nuclear battery and O2/H2O generator. That way we design one cheap, rugged, relatively low-weight and low-volume piece of gear and then just mass-manufacture it. Also no astronaut would ever be far from water or air, and there becomes a zero chance of death by asphyxiation or dehydration.

It's easy to disprove a negative. Simply find life on Mars.

I think you meant, it's impossible to prove a negative. More specifically, to prove that something does not exist.

Not a great headline; fission reactors have been critical part of the Mars Design Reference Mission architecture for the last quarter-century. The news seems to be that NASA is starting to test prototypes (which is definitely still cool).

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

MDRM 5.0 PDF (big file; power generation is 7.3.4, page PDF-pg#85): https://www.nasa.gov/pdf/373665main_NASA-SP-2009-566.pdf

The best part about this article is this picture -- https://media2.s-nbcnews.com/j/newscms/2017_26/2057221/snap_...

I'm strongly in favor of going to Mars, but maybe we should also work on fixing up our home planet too.

Wouldn't the moon would be a better choice? Asteroids could be processed there, it could be a de facto source of microwave power for asteroid mining ops and a weigh station to bring metals back safely.

The moon is boring, Mars once had water and very likely life on it. Moon has a month-long day/night cycle and less gravity, two thing humans aren't well adapted.

Anyone know what the projected cost of transport, setup, shielding and maintenance etc. is?

With existing and conceivable technology, I would project them as effectively infinity. The whole thing is only good for PR.

Are there fissionable materials on Mars?

Sure there is uranium on Mars. But extracting and refining it won't be easy.

Probably cheaper to just put the fuel rods on the rocket with the reactor for the foreseeable future...

Enriched uranium has a very high energy density. 20% enriched Uranium would contain 16TJ/kg.

So a 4MW u-battery would use around 8kg fuel per year.

>Enriched uranium has a very high energy density. 20% enriched Uranium would countain 16TJ/kg.

I did not count in burnup ratio. A simple thermal neutron reactor can only use <1% of fission energy in its fuel.

I'm pretty sure that conventional reactor split around as much fuel as the U-235 content.

For conventional reactors it is around 3% and you are left with around 3% fission products.

Natural uranium has around 0.7% U-235. But I0m pretty sure that you would enrich the uranium befor you send it to mars. The 16TJ/kg is for enriched uranium with 20% U-235 content.

Anyway, energy density of nuclear fuel is extremly high. Even if you pay 10000 USD/kg for the transport of fuel to mars, you'd pay around 1 cent/kwh for the transport.

Yes, it will be higher by few times for highly enriched uranium (90%+) or plutonium 239 (because of higher cross-section)

NASA's Kilopower uses sodium coolant, so it's a fast reactor and gets much more energy out of its fuel. It needs enough U235 to kick off the reaction but after that it will fission the U238 as well.

Burnup could still be limited due to fission products poisoning the reaction.

How predictably can we locate Uranium ore using surface topography? Like can we choose a site with a high probability of ore being find near by?

It doesn't matter, as the only infrastructure available for refining fissile isotopes is on Earth. Even if you found appropriate ores directly adjacent to the reactor site, they would still have to be shipped back to Earth to turn them into reactor fuel.

You need fully mature steel, aluminum, and electronics industries on Mars before you can think about UF6 centrifuges. The rocket equation just murders any idea anyone might have about shipping any kind of factory-in-a-box to any other rock in the Solar system--except one that takes in the local regolith and produces a copy of itself, or a similar factory-in-a-box with a different combination of inputs and outputs.

You're trying to jump right from putting the ore in at one end, and getting reactor fuel out at the other, but you apparently need at least a North Korea-sized economy inside the black box to do that, and Mars currently has an economy smaller than Sealand. There are no humans on Mars, and the robots currently there don't mine or farm anything in excess of their own immediate needs.

I'm getting kinda sick of the media putting more & more non-sense in our heads instead of actual news. This is pure fantasy. They can't build nuclear reactors on Mars! The only reason why they write this article is because the topic "Mars" generates large amounts of views. News shouldn't be a bussiness :(

Genuine question: If it's possible to use mini nuclear reactors in satellites then why they just can't land that thing somehow on Mars (like they did with Curiosity) and use it on planet surface to power lab?

Output, and fuels.

Thermoisotopic generators generally rely on plutonium, which is in very low supply, and generate only about 100-200We output AFAIU.

That's enough for electronics and comms on a deep-space mission, but doesn't offer a whole lot of surplus power for planetary activity. Among the reasons that lander craft are so slow-moving (they basically manage a slow crawl) is power demands, though other factors, including navigation and stress, are considerations.

https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...

    > plutonium, which is in very low supply.

Thermoisotopic generators are a bad idea for general power generation for a colony for other reasons (they're low power, you need a lot of them), but it's not a problem that they're in low supply.

That's just because we haven't been making more plutonium recently, because we haven't needed it. We could simply make more.

Pl-238 is very expensive to produce. We are talking millions/kg.

That's a trivial cost when we're talking about sending things to Mars. The Curiosity rover has around 5kg of Pu-238. NASA estimates that restarting production will cost $6M/kg[1]. The total cost of the MSL program is 2.5 billion[2]. That's $30 million out of 2.5 billion, or 1.2%.

NASA has also been buying Pu-238 from the Russians at around $1.5 million/kg[3], which would be $7.5 million for Curiosity, or 0.3% of the cost of the program.

I'm interested in deep-space exploration (but am no expert), and as far as I can tell the reason the US is running out of Pu-238 has absolutely nothing to do with cost.

It's been happening because only NASA has really wanted this, but producing it has been the purview of the military or the DOE.

So the issue has been stuck in some bureaucratic nightmare for decades, the only people allowed to produce Pu-238 didn't need it, and NASA couldn't simply spend a crapload of money to pay another agency or branch of the government to restart production due to the way money politics works, even though it was an overall good investment.

So rather than simply restart production at a trivial cost compared to what NASA otherwise spends, it's been easier to buy it from Russia.

As [1] shows there's now a real possibility that Pu-238 will run out, so the US has restarted production.

1. https://www.nasa.gov/pdf/636900main_Howe_Presentation.pdf

2. https://en.wikipedia.org/wiki/Mars_Science_Laboratory

3. http://dailycaller.com/2017/03/28/nasa-wants-to-stop-buying-...

The cost wouldn't be trivial for powering a mars colony.

I'm sure the demand for a colony would scale pretty fast to 100kW or more. Now we are talking about Billions.

So I think that your original point that cost for Pu-238 is not an issue for a colony is wrong.

Small reactors are a much better option as a single ton of fuel could supply a colony with a few MW for decades. You just have to make sure that the largest part is less than 37 tons so it can be transported with a Long March 9.

My original point was that dredmorbius's comment that Pu-238 is in low supply wasn't referencing some law of nature, but a political decision that could be changed.

I said they were a "bad idea for general power generation", so I'm not suggesting that they be used to power a Mars colony, but rather that the reasons not to do so don't include Pu-238 being in low supply.

We also have a low supply of rockets & other infrastructure to colonize Mars, but we can simply decide to make them.

Still, I think any extrapolation of current numbers to say that Pu-238 would be categorically unsuitable for such a purpose is probably premature. Nobody's tried to produce it on a truly industrial scale, which would bring costs down. It has a half-life of around 90 years degrading at 1%/year, so once you produce it it'll power the colony for a long time.

It's also around 6% efficient at generating electricity[1], but 100% efficient at generating heat, which is a huge part of energy requirements on Mars when it comes to human habitation. The Curiosity rover generates 120W of electricity but 2000W of heat.

1. https://physics.stackexchange.com/questions/34203/mars-curio...

There are laws of nature involved. But also of men, nations, and war.

Pu-238 isn't found in nature, but has to be synthesized. The precursor material, U-238 is the most abundant form of Uranium, which is convenient. It's also produce via neptunium-237.

The real complication is that the nuclear synthesis processes are also those used for nuclear weapons production, which makes for some serious complications.

Those complications only apply to nations that don't have a permanent seat on the UN security council. There are no treaty obligations preventing the US or Russia from making Pu-238.

Mini reactors are useless on Mars. The power they generate is waaay to low compared to the money that is needed to bring them there. Also putting nuclear reactors on sattelites almost never happens and is VERY DANGEROUS. It's what the Soviet Union did in the 70s-90s. The last sattelite launched with a nuclear reactor was in 1988.

You have to be pretty insane to launch large amounts of nuclear material from earth in a rocket that can randomly explode in our atmosphere.

U-238 is pretty stable.

They don't have to build it on Mars. A kilowatt scale nuclear reactor is small and also safer and more portable. The Russians have already sent nuclear powered satellites into space.

Yeah, i used the wrong word there. I meant, "put" instead of "build"

Sure they can. That's the whole point! It turns out nuclear reactors scale down surprisingly well.

Relatively speaking. Burnup ratios go up with size. Unless you do blended fuel-moderator designs which as I know, were never built

Triga counts as one of those iiuc.

> They can't build nuclear reactors on Mars!

That's why you build them on earth and transport them to mars.

There are some small designs such as the 4MW(el) u-battery that are small enough for a transport.

Read my 2 comments below. Sry for the confusion.

put a nuclear plant on your fregging moms house. the moon doesn't belong to nasa so fuck off!

Will no one think of the children?! I mean, specifically, NASA's hostage martian slave children. Will the reactors be made half-scale, so they can be operated by the children's tiny hands? Will the children be forced to labor in the plutonium mines, far from OSHA oversight?

The last time I heard about humanity settling on Mars on behalf of an Aerospace Corporation, it was about opening a gate to hell.

We just have to make sure that there's a Marine onboard. Or maybe a nuclear scientist with a crowbar.

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