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  1. I exchanged emails with Weir last October objecting to his characterization of the RTG technology. Having worked at NASA Glenn in the Spaceflight Systems division that operates the space nuclear program, I pointed out, based on this experience, that the RTGs that were sent to Mars were also engineered to survive a failed launch. Think about it – NASA does not want a perfectly good launch pad contaminated with PU-238. If the RTGs can survive that, they certainly are not the threat portrayed in the book or the movie.

    For his part, Mr. Weir said, and I am paraphrasing, that the “danger” of the RTG was included for dramatic effect in the book and this was carried over in the movie as well. It appears that as with any treatment of technology by Hollywood that there are limits to realism, especially if they get in the way of entertaining audiences.

    1. The catch here is that an inaccurate depiction of a technology can have severe public perception and energy policy ramifications. i.e. “China Syndrome” and “The Simpsons”, so it behooves engineers and scientists to either demand Hollywood get it straight or do newscast follow-ups to straighten out misconceptions. The failure to do this since TMI is greatly why U.S. nukes have a toilet public regard today.

    2. @Dan

      Good job directly challenging the author. Did you write about that exchange for Neutron Bytes? I’d like to add that link to this post if you did.

  2. If memory servers, the book indicates that the RTG was buried as a disposal method and was not being used by the mission at that point. Why the mission profile would call for the disposal of a perfectly good, reliable, operational power source is beyond me though.

    1. Especially a 100%-reliable HEAT source, when cold is one of the biggest dangers of the planet.

    2. Why the mission profile would call for the disposal of a perfectly good, reliable, operational power source is beyond me though.

      It was to prevent offending the locals. Everybody knows that Martians are green and Greens hate anything that is even remotely associated with “nuclear.”

    3. Yes indeed, which begs another question…

      One way to damage an ultra tough RTG would be to bury it in a highly insulating medium like Martian sand. If it’s producing 1-2KW of heat, where would that heat go?

      Using a RTG is probably a lot safer than disposing of it.

      1. Saw the discussion below. It would probably turn the sand into glass first, which is a better conductor.

        But the electronic components would burn out.

        Giant RTGs (or rather spent fuel casks) placed on the Martian polar caps could be a useful tool for creating some global warming on Mars.

  3. It would be good to upvote that answer since the other two answers to the same question, while accurate as to the purpose of the RTG and how it works, do not mention this error. Incidentally, Weir explains ‘all the ways Mars wants to kill you’ here: http://tinyurl.com/zge5tzf

  4. For a book praised for its realism and depiction of the science it puzzled me how bad researched and described the RTG. Examples:

    “But they never used large RTGs on manned missions until The Ares Program.”

    The RTG described in the book (“2.6kg of Plutonium-238, which makes almost 1500 Watts of heat. It can turn that in to 100 Watts of electricity”) is pretty much a SNAP-27 (3.8 kg of Pu-238), the same used in the Apollo missions.

    “How dangerous is it?” Teddy asked.

    As long as the container’s intact, no danger at all. Even if it cracks open he’ll be ok if the pellets inside don’t break. But if the pellets break too, he’s a dead man.”

    And

    “Speaking of cancer, it was time to get rid of the RTG.

    It pained me to climb back into the rover, but it had to be done. If the RTG ever broke open, it would kill me to death.”

    Why would the Pu kill him if the pellets breaks? nobody knows.

    1. Alpha radiators are highly lethal if ingested. Breaking means fragments will be released, and get loose inside the compartement.

      Which is why NASA designed the things so they can’t break even if the rocket explodes.

      1. @10ebbor10

        Without quantification, your statement “alpha radiators are highly lethal if ingested” is untrue. For example, U-238 is an alpha emitter, but its decay rate is so slow and its biological uptake is so low that humans can ingest a rather large quantity before it becomes “lethal” over any meaningful time span. Chemical harm from its heavy metal qualities is more likely than harm from its alpha emissions.

        Po-210, on the other hand, decays very rapidly. Even a very tiny amount is highly lethal in a relatively short, but painfully long period of days to weeks.

  5. It is unlikely that technical realism will defeat Hollywood’s desire for a thrill. Anyone who has seen any of the Godzilla monster movies can provide numerous examples. And then there is Star Trek . . .

    At least in the movie The Hunt for Red October, you have this exchange,

    Captain, to first officer: “Inquire of the engineer about the possibility of going to one hundred and five [percent] on the reactor”

    First officer: “Captain, the engineer reports one hundred and five percent on the reactor possible, BUT NOT RECOMMENDED”

    Captain: …”go to one hundred and five on the reactor…”

    1. Ice Station Zebra: (Ernest Brognine wandering around inside nuclear sub): Er, hi Captain! I’m looking for the nuclear reactor.
      (Captain Rock Hudson): You’re standing on it.

      At least nuclear wasn’t a baddie in ISZ, but didn’t need Roc saying: “But it is nuclear energy, and it hates being confined and will break loose any chance it gets…” Not good nuke PR…

  6. Gordon Mcdowell recently put out a film on the synergies of space exploration and nuclear energy and covered the film’s use of RTGs: https://www.youtube.com/watch?v=0BybPPIMuQQ

    The Juno spacecraft recently arrived at Jupiter as one of the few objects to make it past the asteroid belt without the use of a RTG. Solar enthusiasts like to point out how the Juno probe is powered, however; it is funny to note that the solar powered Philae Lander ran out of juice after it landed in a shadow on comet 67p. Apparently the European Space Agency prohibits the use of RTGs for safety and political reasons.

    1. To be fair I’m not sure it would have been plausible to use a RTG on such a small probe like the Philae. People sometimes forget that the primary mission is what Rosetta is doing, Philae was a “cheap” extra, and still got data. I’m more puzzled by the fact that all attach mechanisms failed.

        1. @E-P

          Pu-238 will never be cheap or abundant, but the way that the US has chosen to produce in tiny batches with large production gaps makes it far more precious than it should be.

          1. Given the tiny neutron-capture cross-section of U-236 I can see why Pu-238 will never be abundant.  I still wonder if an active fuel reprocessing and re-enrichment industry wouldn’t produce a fair amount of it as a byproduct.

          2. ‘the way that the US has chosen to produce in tiny batches with large production gaps makes it far more precious than it should be.’

            Can’t have the ignorant voting consumers learning there IS a safe, relatively inexpensive nuke option suitable for distributed mains electrics generation to replace fossil fuels – like the nuke cell powering Sheriff Carter’s underground bunker house in TV’s ‘Eureka’. 🙂

            1. @Larry Pines

              Few of us know about the power source for Sheriff Carter’s underground bunker. But I always liked the concept and the fact that the show characters were quite accepting of the benefits of a clean, always available power source.

            2. Plutonium 238 results from special processing. Neptunium 237 is separated out chemically from used fuel, then neutron-irradiated, then the plutonium 238 is chemically separated out. Hence the batch processing with “production gaps”. Pu-238 has a half life of 88 years, so if you want full power on your spacecraft in 88 years from the date of processing, you would have to launch it with twice the mass of hot metal. There is an alternative.

              Americium 241 is a similar alpha-emitter with a half life of 470 years. At first glance, it would seem that you would have to launch five times the mass of contained plutonium, but you wouldn’t have to provide an excess as with the plutonium. In the wet reprocessing of used fuel, americium 241 is routinely separated out for use in smoke detectors. No further irradiation is required so the stuff can potentially be obtained fresh from any country with wet reprocessing.

              1. @Roger Clifton

                Interesting. One way that I have seen isotope heat sources for RTG use compared is by their heat production per unit of mass. This directly helps engineers determine how much of the heat source they need to produce the power their applications demand.

                Do you know how Am-241 compares to Pu-238 on this measure?

                1. According to Wikipedia, when fresh and in chemically inert form, Pu-238 has a power density of 0.54 kW/kg and Am-241 has 0.114 kW/kg. The ratio is approximately five times, much as the ratio of their half lives indicate. However the plutonium is fading at 7.6% per decade whereas the americium is fading at only 1.6% per decade.
                  https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
                  European Space Agency is planning to use americium RTG’s in space.
                  https://en.wikipedia.org/wiki/Americium-241#rtg
                  Americium certainly seems to be appropriate for powering remote applications such as radio beacons in the Arctic.

    2. Exactly as Jose A. speculates, probe was too small for RTG, whose minimal configuration is still pretty heavy and would require substantially larger probe, thus effectively tanking the whole plan.

  7. “I remain perplexed that no one in the technical review chain of the movie wondered aloud why RTGs have fins.

    Even space geeks should recognize heat sinks when they see them. RTGs produce electricity using the semiconductor thermoelectric effect discovered by Seebeck nearly 200 years ago. One junction is heated by the decay of Pu-238, but if the other junction has no way to reject heat by either radiation, convection or both, temperatures across the two junctions equalize. At that point, no current will flow. No one who knows how the devices work would bury them.”

    What has higher conductivity, and is a better heat sink against the fins, (a) Very low pressure CO2 atmosphere, or (b) Martian “regolith?”

    Doh!

    1. @Pu239

      RTG fins mostly work through thermal radiation or convection (moving fluids). Designed to function in vacuum as well as in atmosphere.

      Neither of those modes of heat transfer work underground. The only one remaining is conduction, but loose Martian soil – like most sandy dirt – is a pretty poor conductor.

      “Heat conduction through the matrix is limited by the bottle necks at the contact points of single silicate or ice grains. In loose aggregates these contact points provide very little cross section area and thus cause a substantial decrease on the ability to conduct heat.”

      http://www.lpi.usra.edu/meetings/polar2006/pdf/8048.pdf

      Back at you.

      1. So, with no heat removal, the plutonium heat source would have melted, vaporized, burst or melted its container, and dripped or boiled away, due to a near perfect insulation, and nearly steady heat source? (No)

        “or convection (moving fluids)”
        “Neither of those modes of heat transfer work underground.”

        Your own reference contradicts:

        “In addition to solid state heat transport through the matrix, heat is transported by gas. In cold regions where ices are present at least for cold nights or seasons, the pore-filling vapour will also transport latent heat – a process that is very effective in comets, but not taken into account in most thermal models of Martian near surface layers.”

        Figure 2 for simulated Mars soil (JSC-1) shows a range of conductivity that is above insulators to nearly as high as engine oil or alcohol.

        Don’t forget the surface temperature would be quite cold most of the time.

        1. @Pu239

          I didn’t say there was no heat removal. The soil near the buried RTG would heat up and continue conducting a small quantity of heat to the surrounding soil. Eventually that heat absorption would equal the rate of heat production of the PuO2 and temperature would stop increasing. The melting point of PuO2 (2390 ℃) would never be approached.

          Damage prevention in the case of an RTG being buried in soil as a result of a launch or reentry accident is one of the many design criteria for the devices.

          I didn’t notice any indication in the movie that Watney was stranded in region where there is ice present.

          I wasn’t trying to say that it would be dangerous to bury an RTG, just that burying the device would make it stop functioning as an electrical power source.

          1. “I didn’t say there was no heat removal. ”

            Re-read what you originally wrote about “no way to reject heat” and “temperatures across the two junctions equalize.” Seems essentially the same to me. No delta-T, no heat removal.

            ” just that burying the device would make it stop functioning as an electrical power source.”

            Heat removal requires delta-T, and the same heat has to flow out, whether sitting on the surface or buried underneath. It seems like the thermocouples will have similar delta-T either way. Assuming the whole thing gets to steady state rather than melting down.

            Absent any real evidence otherwise, my intuition says the whole thing operates cooler underground than on the surface. Your intuition says it operates cooler on the surface. Either way, doesn’t the heat go out by way of a delta-T across the thermocouples, and therefore, won’t it function either way?

            1. @Pu239

              Sorry for using confusingly absolute terms like “no way”, “equalize”, and “stop”.

              I should have been more careful to indicate that there was still PuO2 temperature at which heat removal equals heat production, that the overall system of heat source, semiconductor junction, heat sink and surrounding soil would have a temperature gradient and a heat loss at the boundary of that system that is equal to the PuO2 heat production. The functional problem that I was trying to point out is that the soil is a pretty good insulator and that the temperature gradient that is supposed to occur mainly across the semiconductor junction would be mostly spread out over the surrounding soil.

              The hot and the cold side temperatures of the semiconductor junction will not completely equalize, but they will be substantially closer together than they would be without the insulating effects of the soil, causing a large reduction in the power output.

              My description doesn’t use numbers or equations, but it is slightly more rigorous than mere intuition. It’s what we used to call “arrow analysis” in the nuclear navy where we did not care too much about exact numbers, but we wanted people to understand relative magnitudes enough to understand the overall system effect of various changes. I could take the time to look up all of the numbers and produce a reasonably precise sketch of the system showing the temperature drops through various layers, but I have other fish to fry.

              In Weir’s fascinating tale of how Watney conquers a planet that is trying to kill him, lack of electricity from the RTG apparently didn’t concern the crew as much as protecting themselves from its greatly exaggerated radiation hazard. As I recall, the buried RTG didn’t have any loads connected to it and Watney simply used the rejected heat without plugging it into his Rover power system.

              That helps provide dramatic tension by making the task harder and the eventual solution more heroic that it really needed to be. Great for a story line, bad for the public understanding of the usefulness of radioactive decay energy.

              Verisimilitude isn’t terribly important in movies where nearly everything is made up, but it is in movies that lay claim to working hard to get the science right.

  8. Rod,

    Loved the movie. Unfortunately Andy spend great deal of time nailing the hard science, and kinda glossed over some simple stuff for sake of dramatic tension.

    (IMHO we’re manufacturing a heck of a lot of dramatic tension these days in the real world nevermind on Mars.)

    The book actually has a lot more detail regarding the challenges of solar power… and unfortunately even more detailed articulation of supposed danger of RTGs.

    It is still worth reading… I mean I couldn’t put it down the first time I read it. But the stuff that is made-up is pretty weird…

    Like on one hand (in the book) Mark has to tediously deal with a sand storm cutting into his solar power as he’s driving across Mars. Realistic as far as I can tell.

    On the other hand, the sand storms are being blown in very thin air, so the “blackout” shown in the movie is a visual exaggeration. And there’s no strength to it, so it isn’t like any heavy objects get blown around or like the wind could tip the MAV.

    [Shrugs.]

    Andy’s the guy who wrote a best-selling book, and got a Hollywood movie made out of it. So clearly dangerous RTGs and sandstorms that blow people around are what’s called for.

    Keep an eye on Juno. If it runs out of power (and I’m hoping it does not) then would be an opportune time to reiterate solar-vs-RTG arguments.

    1. Solar vs RTG arguments can still be made no matter what:

      Juno, 340 kg of solar panels, 486 W on Jupiter declinig to 420 W as radiation degrades the cells in its one-year mission.

      Galileo, two GPHS-RTGs weighting 114 kg, 485 W at the end of mission after 8 years in the Jovian system.

  9. Excellent points, Rod. The other main science faux pas was the wind. The atmosphere is not dense enough to move anything above a piece of paper, even at 100 miles an hour. But the movie is still fantastic, especially to an old planetary geologist like me!

      1. Sorry, a 150 mph wind at the surface is equivalent to a 10 mph wind on earth, so yes, it would flap. But it couldn’t destroy the stuff it did in the movie.

      1. I’m pretty sure there’s a bunch of folks out on the desert at Argonne West in Idaho running around with “unlicensed nuclear accelerators” so they can toast marshmallows on the fired up sagebrush. After all, Materials Fuels Complex is really a code name for “mighty fine cookies” S’Mores anyone?

  10. We could do worse…..

    Hell, I just watched a show last night (The Last Ship) where they said that due to a meltdown of a nuclear power plant 6 miles away, there is a local area (hot spot) with radiation levels that would kill you in ~10 minutes!

    NRC website says that 400 Rem (delivered over a short period) is the LD 50/30. I suppose 10 min counts as a short period. So that’s ~2400 Rem/hr. That is almost the dose rate on the surface of spent fuel or the surface of a large mass of corium (such as the “elephant foot” in the basement of Chernobyl). It’s also over a *million* times higher than the maximum dose rate seen anywhere around Fukushima, at any time after the meltdown.

  11. Commet about fins on RTG, 1) the book THE MARSHAN does a better job of explaining the issue as to the dangers and consequences posed by a RTG, both positive and negative 2) could the fins have been cooling fins for the RTG 3) Maybe their technical staff just saw fins in the description of what should be on a RTG and just assumed fins like what would be found on a bomb instead of fins ln a heat sink 4) If short on reading time Audible.com is a excelent source for audio books such as THE MARSHAN

  12. Goes without saying that no one would bury an RTG either, nor protect us from it, because Mars is uninhabited.

    1. >> Goes without saying that no one would bury an RTG either, nor protect us from it, because Mars is uninhabited. <<

      Exactly. That pointless act made nuclear radiation look even more forbiddenly dangerous to the great NPP-adverse unwashed. I mean what does that say to John Q Public if there's something is SO dangerous you have to BURY it on an uninhabited planet WITH a skull and crossbones on top?? Ripe for anti nuke waste propaganda.

  13. Space nerds, despite the nerdiness, are surprisingly oblivious to the need to dispose of waste heat on space vehicles and structures.

    I always imagined that the great panels on Babylon V (anyone remember that) were radiators, not solar panels, or perhaps one side of each, despite JMS writing that they wete solar panels. In show, the station already has a fusion reactor and all of its power will eventually be waste heat somewhere in the station…

    The space shuttle had radiators lining the insides of the cargo bay doors. If the cargo bay doors would not open for some reason, the mission must be aborted within a matter of hours.

    1. The authors and artists who create space stations for TV typically aren’t very serious space nerds.  They’re usually not very good at physics either.

    2. Those huge long panels on Babylon 5 weren’t power panels or radiators but day-night simulation mirrors that mimic the setting and rising of the sun inside while the station revolved. That’s how you got night scenes. This is delved into with the l-5 Society’s info.

  14. Now what do you mean, Rod, by “even space geeks”?
    The space geeks I know — speaking here as a director of one Space Society & past director of another (talking international organizations, not local chapters), & frequent attendant & occasional presenter at space conferences — are quite familiar with the simple fact that Apollo (ALSEP) RTGs have radiator fins, while the MSL Curiosity unit does not.

    Andy Weir, by the way, is a fun guy, inventor of cross-country water skis, concerning which he reports that sustained use is quite beyond human muscular capacity.

    1. @publius

      Terrific. And I’m sure that they know why the Curiosity’s RTG doesn’t depend on radiator fins for heat removal. As we know, space system designers work hard to eliminate waste and consider weight, space, and heat to be precious enough to be carefully used for multiple purposes.

      That philosophy, by the way, is one of the reasons I was jarred by the notion that the Mars exploration team would purposely bury an RTG, seemingly because they were trained to be afraid of it instead of considering it to be a valuable resource.

  15. Rod Adams:

    “The hot and the cold side temperatures of the semiconductor junction will not completely equalize, but they will be substantially closer together than they would be without the insulating effects of the soil,…”

    “It’s what we used to call “arrow analysis” in the nuclear navy where we did not care too much about exact numbers, but…”

    Either there is a property of these junctions and RTG construction you have failed to explain in 3 responses, or one of us doesn’t understand heat transfer very well. If the soil/dust is as insulating as you say, then an RTG might be nearly as vulnerable to dust coatings as solar panels are. Oh well, enough of that.

    “As I recall, the buried RTG didn’t have any loads connected to it and Watney simply used the rejected heat without plugging it into his Rover power system.”

    So, in summary, whether it was buried or not made no difference, because it didn’t matter if it produced electricity or not. Much ado about not much.

    Regardless, this post is another example of typical blog flaws as compared with better journalism. On every issue, you could get accurate summary information or confirmation from real expert sources who know the details, but you apparently don’t have the time, and choose the sensational approach, like in the movies.

    What is the dose to an astronaut from exposure to a damaged RTG? Many estimates and measurements of dose rates from the sources and RTGs should be available, but not necessarily on-line. It won’t be only from pure Pu-238 oxide, and it won’t be from only “pure alpha” emission. How does that dose compare with the already high dose from just going to Mars? Probably small, but some real information would be better than “arrow analysis” guessing.

    (ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690025340.pdf on SNAP-27 sources, 81% pu-238, 15% pu-239, neutron and gamma sources, Table 4-17: 9.5 mRem/Hr gamma, 53.8 mRem/Hr neutron, at 1 meter, it could add up inside the rover)

    I think you were more offended by the “danger” flag than anything, and made an issue of a minor point rather than the more fundamental dose comparison.

    Gordon McDowell:

    “On the other hand, the sand storms are being blown in very thin air, so the “blackout” shown in the movie is a visual exaggeration. And there’s no strength to it, so it isn’t like any heavy objects get blown around or like the wind could tip the MAV.”

    and

    Jim Conca:

    ” a 150 mph wind at the surface is equivalent to a 10 mph wind on earth, so yes, it would flap. But it couldn’t destroy the stuff it did in the movie.”

    Severe, global dust storms on Mars are real hazards. Based on the pictures and discussion here, “blackout” doesn’t seem too exaggerated:

    (science.nasa.gov/science-news/science-at-nasa/2001/ast11oct_2/)

    While the force of the wind is less than on Earth, the force of gravity holding things in place is also less than on Earth (though by a smaller ratio). So, the impact of the wind force was exaggerated some, but dangers from blowing dust probably weren’t.

    Rod Adams:

    “Pu-238 will never be cheap or abundant, but the way that the US has chosen to produce in tiny batches with large production gaps makes it far more precious than it should be.”

    Consider the source…

    (cms.doe.gov/ne/nuclear-reactor-technologies/space-power-systems)

    and why don’t you tell more about the real drivers of production, assuming you know? That’s the real travesty.

    1. @pu239

      one of us doesn’t understand heat transfer very well

      Very true. I’ll let others decide which one.

      So, in summary, whether it was buried or not made no difference, because it didn’t matter if it produced electricity or not. Much ado about not much.

      Why would NASA spend the money to produce an RTG and allot the space and rocket fuel needed to lift it off of the Earth and transport it to Mars if it’s mission protocols led it to be buried, not used for electricity and marked with a danger flag? Again, I’ll forgive all kinds of literary devices for an entertainment that does NOT market itself as paying great attention to scientific details. Weil might have spent time getting the geographic features and their difficult to remember names right, but he blew it on this rather important technical details of mission planning and power engineering.

      and why don’t you tell more about the real drivers of production, assuming you know? That’s the real travesty.

      That wasn’t the topic of this post.

      My statement was a one sentence summary of far more detailed articles like Wired’s September 19, 2013 article titled NASA’s Plutonium Problem Could End Deep Space Exploration along with my perspective on DOE/NASA budget battles and political avoidance of used fuel recycling to extract valuable isotopes instead of blithely calling it all “nuclear waste.”

      Perhaps I’ll take the time in the future to provide a detailed analysis of how antinuclear activism is destroying space exploration. However, as you pointed out, I’m just an opinionated blogger working on a shoestring budget with responsibilities for research, fact checking, writing, editing, site maintenance and floor-sweeping, not a journalist working for a large budget commercial operation.

      1. That wasn’t the topic of this post.

        Right. This topic was criticizing a fiction writer for some technical nitpicks you didn’t have time to check carefully, while also criticizing him for not taking time to check carefully. Then calling it jarring errors, because he wasn’t 100% pro-nuke, and had some concerns about safety. You could have chosen to emphasize how he found a way to use nuke power to save the day, but that’s just not negative enough for headline material.

        I didn’t notice any indication in the movie that Watney was stranded in region where there is ice present.

        It seems dry ice is wide spread.

        ( http://www.nasa.gov/feature/frosty-cold-nights-year-round-on-mars-may-stir-dust )

        My statement was a one sentence summary of far more detailed articles…

        The problem with any discussion of nuclear power topics, including RTGs and your detailed article, is the real issues are only discussed behind walls of security, and there is always more to the true story. The public is right to distrust overly simple phrases like “reliable, robust, compact, well-proven and rigorously-tested…” or “a pure alpha particle emitter like Pu-238.”

        working on a shoestring budget with responsibilities…

        As if Weir had much more support when he wrote the articles and self-published them on the web:

        ‘I had chemists, electrical engineers emailing me, and a reactor tech on a US nuclear submarine, just telling me how this stuff works. It was really nice because I didn’t have any contacts in aerospace at the time. I didn’t know anyone in Nasa, so all my research was on Google.’ ( http://www.telegraph.co.uk/film/the-martian/andy-weir-author-interview/ )

        On the windstorm:

        “A Martian sandstorm can’t do any damage. And I knew that at the time I wrote it.”

        ( http://www.npr.org/2015/09/27/443192327/sandstorms-explosions-potatoes-oh-my-martian-takes-its-science-seriously )

        He may have done better to bury the RTG under a sand dune caused by several months of historic sand storm.

        There are a number of things wrong with that passage.

        And there are a number of things wrong with your list of wrong things, including just plain wrong description of the real source material and its radiation emissions. Common sense says nothing is that simple, and 10-30 minute web searches find technical reports showing RTGs have about 80% Pu-238, 15% Pu-239, other Pu isotopes, thorium, and uranium; and radiation emissions around the sources including significant levels of neutrons and gammas. This is not “pure Pu-238” nor “pure alpha emitter.”

        ( ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690025340.pdf )
        ( ntrs.nasa.gov/search.jsp?R=19710014240 )

        1. @pu239

          I wasn’t criticizing a poor, do-it-yourself fiction writer. I was criticizing the finished product of a big budget Hollywood movie that I’ve heard several SciCom podcasters rave about for its huge efforts to get the science right. The big bucks marketing for the movie also focused on its realism.

          Yes, I’m adamantly pro nuclear science and engineering. I get personally offended by the vast quantity of misinformation that has been purposely spread over more than half a century. It is a technology worthy of respect and understanding, not Fear, Uncertainty, and Doubt.

          1. I get personally offended by the vast quantity of misinformation that has been purposely spread over more than half a century.

            About this we agree, in general, except I don’t take it personally. Yet you use the same tactic, and you swore you would about some things, for “security.” Telling half-truths is also spreading misinformation.

            Yes, this statement by Weir is ignorant: “Even a small radiation leak would be almost immediately fatal,” but concern about high radiation exposure in space, or from being close to an RTG, seems valid. More valid than you portray with your “pure Pu-238, pure alpha emitter” misinformation.

            Maybe you’d like to comment on the radiation effects portrayed in Moon (2009). It was worth watching.

            ( http://www.imdb.com/title/tt1182345/faq )

  16. I guess the worst thing that NASA could do on mars is to bury a RTG.
    Sand, rock and dirt are very good insulators.
    Yeah.. it may be some water that gets evaporated first, but when that is over, each time that the heat move 1 cm away of its source would be harder and harder to lose heat.
    This is simple math, no because the rock around heat up it means that it would keep spreading, if that would be the case, then it would be the same to have 1 cm of insulator than 1 meter of it, if time is the only thing that requires to have the same flow of heat.. that is not how heat transfer works.

  17. Hi Rod, I’m a complete non-expert in this area and am curious how small an RTG could theoretically be made. The ones I’ve seen described are all designed for various vehicles; could the technology be adapted for use by individuals operating in extreme environments?

      1. Thanks Rod, that’s really interesting. Could the actual heat output be of any use at that scale (eg: heating a survival suit), or would it be purely this sort of thermoelectric application?

        Also, I’m keen to understand the underlying principles better, so if you can point me to solid source material for further reading that would be great!

        1. Gareth:

          There is a fairly comprehensive set of articles about RTGs here. Look in the Archives – Categories – RTG. Many of the articles in that category were first published in the Sept 1996 issue of the paper Atomic Energy Insights before we moved on line and changed the publication name to Atomic Insights. There is even a list of sources.

          A few of the articles discuss more recent RTG related topics.