16 ms·

NASA Revives Plan to Put Nuclear Reactors on Mars

204 points by curtis 9y ago

sp0ck 9y ago
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.
- mikejb 9y ago
  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.
  - Ntrails 9y ago
    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".
    - kobeya 9y ago
      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.
      - Symmetry 9y ago
        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.
        mathw 9y ago
        Sure it's not in critical mass or particularly radioactive, but Plutonium is toxic...
        wbl 9y ago
        So is hydrazine and dinitrogen tetroxide is also all kinds of fun. Heavy metal toxicity is manageable.
        DennisP 9y ago
        NASA's Kilopower design uses enriched uranium fuel, and with such a small reactor it won't be much uranium.
        Symmetry 9y ago
        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.
    - davedx 9y ago
      > 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.
      - Retric 9y ago
        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.
      - londons_explore 9y ago
        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.
        Retric 9y ago
        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.
- tiku 9y ago
  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.
  - danpalmer 9y ago
    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.
    - mikejb 9y ago
      "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.
      - DiThi 9y ago
        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.
        mikejb 9y ago
        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.
- simias 9y ago
  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.
  - krasin 9y ago
    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.
    - nkrisc 9y ago
      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.
      - mirimir 9y ago
        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 ;)
      - nsxwolf 9y ago
        Culture is better at transmitting ideas and changing perceptions than elitist blowhards are.
  - tehwalrus 9y ago
    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!
- mtgx 9y ago
  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.
  - valuearb 9y ago
    Yes, it's been much tested. They aren't operational until they make orbit.
- MichaelMoser123 9y ago
  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?
  - freehunter 9y ago
    Do you know how much nuclear material we've launched into space? Hint: a lot.
  - DennisP 9y ago
    Irrational because a uranium fission reactor contains very little radioactivity before you start running it.
  - tajen 9y ago
    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?
  - yongjik 9y ago
    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.
  - gene-h 9y ago
    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.
foota 9y ago
Are there fissionable materials on Mars?
- nradov 9y ago
  Sure there is uranium on Mars. But extracting and refining it won't be easy.
  - davedx 9y ago
    Probably cheaper to just put the fuel rods on the rocket with the reactor for the foreseeable future...
    - xorfish 9y ago
      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.
      - baybal2 9y ago
        >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.
        xorfish 9y ago
        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.
Knufen 9y ago
Anyone know what the projected cost of transport, setup, shielding and maintenance etc. is?
- zeofig 9y ago
  With existing and conceivable technology, I would project them as effectively infinity. The whole thing is only good for PR.
timtosi 9y ago
The last time I heard about humanity settling on Mars on behalf of an Aerospace Corporation, it was about opening a gate to hell.
- arkitaip 9y ago
  We just have to make sure that there's a Marine onboard. Or maybe a nuclear scientist with a crowbar.
legulere 9y ago
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.
- dredmorbius 9y ago
  Sterling-cycle generator, utilising heat pipes, based on this study (PDF): http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-14-23402 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 https://en.m.wikipedia.org/wiki/Kilopower
  - jwilk 9y ago
    Non-mobile link: https://en.wikipedia.org/wiki/Kilopower https://en.wikipedia.org/wiki/Kilopower
- rocky1138 9y ago
  https://en.m.wikipedia.org/wiki/Thermophotovoltaic https://en.m.wikipedia.org/wiki/Thermophotovoltaic
cortexio 9y ago
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 :(
- 8draco8 9y ago
  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?
  - dredmorbius 9y ago
    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_generator https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...
    - avar 9y ago
      > 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.
      - xorfish 9y ago
        Pl-238 is very expensive to produce. We are talking millions/kg.
DanielBMarkham 9y ago
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.
- moovacha 9y ago
  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.
davedx 9y ago
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/20160012354.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201600... [2] https://www.nasa.gov/mission_pages/station/structure/elements/solar_arrays.html https://www.nasa.gov/mission_pages/station/structure/element...
- Symmetry 9y ago
  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.
deleted 9y ago
[deleted]
SCAQTony 9y ago
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.
- TomK32 9y ago
  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.
  - deleted 9y ago
    [deleted]
  - deleted 9y ago
    [deleted]
  - SCAQTony 9y ago
    I am astonished by your comment. In no way would Mars assist the earth whatsoever economically or as a safe haven. The purpose of spending billions upon billions on an off world reservation where you could never go outside or produce anything productive for the earth is not worth it. IMHO the moon is not boring it would be vital if we take mining for metals off world and perhaps discover new ways clean up out carbon issues and economic disparity.
Cumulonimbus 9y ago
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.
- TomK32 9y ago
  Bulding the Network is the best part about KSP, right?
- SEJeff 9y ago
  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-billion-investment-in-spacex.html https://www.nytimes.com/2015/01/21/technology/google-makes-1...
  - Retric 9y ago
    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.
    - monocasa 9y ago
      > 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.
Finnucane 9y ago
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?
notadoc 9y ago
I'm strongly in favor of going to Mars, but maybe we should also work on fixing up our home planet too.
Horizon_Blue 9y ago
Before anybody asks "but what happens if the rocket blows up during launch": the reactor doesn't become significantly radioactive until after it's turned on. If anything it's quite a bit safer than the radioisotope thermoelectric generators currently in common use.
pheldagryph 9y ago
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 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 https://www.nasa.gov/pdf/373665main_NASA-SP-2009-566.pdf
vectorEQ 9y ago
put a nuclear plant on your fregging moms house. the moon doesn't belong to nasa so fuck off!
jasonrhaas 9y ago
The best part about this article is this picture -- https://media2.s-nbcnews.com/j/newscms/2017_26/2057221/snap_post_card_2e783660691421a54fa05af239bc7af4.focal-678x886.jpg https://media2.s-nbcnews.com/j/newscms/2017_26/2057221/snap_...

204 points by curtis 9y ago

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.

mikejb 9y ago
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.
- Ntrails 9y ago
  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".
  - kobeya 9y ago
    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.
    - Symmetry 9y ago
      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.
      - mathw 9y ago
        Sure it's not in critical mass or particularly radioactive, but Plutonium is toxic...
        wbl 9y ago
        So is hydrazine and dinitrogen tetroxide is also all kinds of fun. Heavy metal toxicity is manageable.
        DennisP 9y ago
        NASA's Kilopower design uses enriched uranium fuel, and with such a small reactor it won't be much uranium.
        Symmetry 9y ago
        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.
  - davedx 9y ago
    > 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.
    - Retric 9y ago
      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.
    - londons_explore 9y ago
      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.
      - Retric 9y ago
        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.
tiku 9y ago
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.
- danpalmer 9y ago
  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.
  - mikejb 9y ago
    "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.
    - DiThi 9y ago
      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.
      - mikejb 9y ago
        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.
simias 9y ago
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.
- krasin 9y ago
  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.
  - nkrisc 9y ago
    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.
    - mirimir 9y ago
      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 ;)
    - nsxwolf 9y ago
      Culture is better at transmitting ideas and changing perceptions than elitist blowhards are.
- tehwalrus 9y ago
  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!
mtgx 9y ago
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.
- valuearb 9y ago
  Yes, it's been much tested. They aren't operational until they make orbit.
MichaelMoser123 9y ago
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?
- freehunter 9y ago
  Do you know how much nuclear material we've launched into space? Hint: a lot.
- DennisP 9y ago
  Irrational because a uranium fission reactor contains very little radioactivity before you start running it.
- tajen 9y ago
  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?
- yongjik 9y ago
  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.
- gene-h 9y ago
  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.

foota 9y ago

Are there fissionable materials on Mars?

nradov 9y ago
Sure there is uranium on Mars. But extracting and refining it won't be easy.
- davedx 9y ago
  Probably cheaper to just put the fuel rods on the rocket with the reactor for the foreseeable future...
  - xorfish 9y ago
    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.
    - baybal2 9y ago
      >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.
      - xorfish 9y ago
        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.

Knufen 9y ago

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

zeofig 9y ago
With existing and conceivable technology, I would project them as effectively infinity. The whole thing is only good for PR.

timtosi 9y ago

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

arkitaip 9y ago
We just have to make sure that there's a Marine onboard. Or maybe a nuclear scientist with a crowbar.

legulere 9y ago

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.

dredmorbius 9y ago
Sterling-cycle generator, utilising heat pipes, based on this study (PDF): http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-14-23402 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 https://en.m.wikipedia.org/wiki/Kilopower
- jwilk 9y ago
  Non-mobile link: https://en.wikipedia.org/wiki/Kilopower https://en.wikipedia.org/wiki/Kilopower
rocky1138 9y ago
https://en.m.wikipedia.org/wiki/Thermophotovoltaic https://en.m.wikipedia.org/wiki/Thermophotovoltaic

cortexio 9y ago

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 :(

8draco8 9y ago
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?
- dredmorbius 9y ago
  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_generator https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...
  - avar 9y ago
    > 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.
    - xorfish 9y ago
      Pl-238 is very expensive to produce. We are talking millions/kg.

DanielBMarkham 9y ago

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.

moovacha 9y ago
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.

davedx 9y ago

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/20160012354.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201600... [2] https://www.nasa.gov/mission_pages/station/structure/elements/solar_arrays.html https://www.nasa.gov/mission_pages/station/structure/element...

Symmetry 9y ago
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.

deleted 9y ago

[deleted]

SCAQTony 9y ago

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.

TomK32 9y ago
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.
- deleted 9y ago
  [deleted]
- deleted 9y ago
  [deleted]
- SCAQTony 9y ago
  I am astonished by your comment. In no way would Mars assist the earth whatsoever economically or as a safe haven. The purpose of spending billions upon billions on an off world reservation where you could never go outside or produce anything productive for the earth is not worth it. IMHO the moon is not boring it would be vital if we take mining for metals off world and perhaps discover new ways clean up out carbon issues and economic disparity.

Cumulonimbus 9y ago

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.

TomK32 9y ago
Bulding the Network is the best part about KSP, right?
SEJeff 9y ago
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-billion-investment-in-spacex.html https://www.nytimes.com/2015/01/21/technology/google-makes-1...
- Retric 9y ago
  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.
  - monocasa 9y ago
    > 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.

Finnucane 9y ago

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?

notadoc 9y ago

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

Horizon_Blue 9y ago

Before anybody asks "but what happens if the rocket blows up during launch": the reactor doesn't become significantly radioactive until after it's turned on. If anything it's quite a bit safer than the radioisotope thermoelectric generators currently in common use.

pheldagryph 9y ago

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 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 https://www.nasa.gov/pdf/373665main_NASA-SP-2009-566.pdf

vectorEQ 9y ago

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

jasonrhaas 9y ago

The best part about this article is this picture -- https://media2.s-nbcnews.com/j/newscms/2017_26/2057221/snap_post_card_2e783660691421a54fa05af239bc7af4.focal-678x886.jpg https://media2.s-nbcnews.com/j/newscms/2017_26/2057221/snap_...