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What Would Have Happened If Philae Were Nuclear Powered?
StartsWithABang writes After successfully landing on a comet with all 10 instruments intact, but failing to deploy its thrusters and harpoons to anchor onto the surface, Philae bounced, coming to rest in an area with woefully insufficient sunlight to keep it alive. After exhausting its primary battery, it went into hibernation, most likely never to wake again. We'll always be left to wonder what might have been if it had functioned optimally, and given us years of data rather than just 60 hours worth. The thing is, it wouldn't have needed to function optimally to give us years of data, if only it were better designed in one particular aspect: powered by Plutonium-238 instead of by solar panels.
I had the mistaken belief that all space probes / landers were nuke-powered.
Pain is merely failure leaving the body
If only Matt Taylor hadn't worn that shirt, none of this would have happened =(
The solar panels are "green" technology.
I heard through the grapevine that the solar panels narrowly beat out using wind power but they were worried about the wind encountered at such high velocities and the possibility of killing birds.
Basically the US has exhausted its meager supply. And the few supplies existing elsewhere are being jealously hoarded.
There's ways to MAKE more, and improve nuclear power at the same time. But nobody wants to talk about it.
Because nukes = bombs. M'kaaay?
Chas - The one, the only.
THANK GOD!!!
I wonder if the lander's instruments is rated to withstand the conditions brought about from the more intense sunlight.
has stopped dev on nuclear batteries.
silly hippie twits.
If it was nuclear powered, then it would have been much heavier and would require a much longer mission and use something more than single-use devices. The entire scope of the mission would have to change!
The primary batteries were for the main mission, The solar panels were "extras". So, nothing much would have been gained if this was nuclear powered device and nothing else changed.
Nuclear powered spacecraft are only really needed outside Jupiter's orbit. Or perhaps on landers designed to operate for extended period of time with a reliable power supply. For the rest, the extra weight is something that is not desirable.
And if that comet then hit earth, do you know what a huge catastrophe that would have caused?
Then we would be saying 'ah but couldn't they just use solar power?'
this: http://en.wikipedia.org/wiki/R...
...is the idea of a nuclear power device on a satellite exploding on impact.
Correct me if I'm wrong, but wouldn't it have been really bad if there had been a boatload of plutonium-238 on the Challenger?
Doesn't nuclear power work by boiling water? Doesn't it require that steam then turning back to water?
Uh, no.
Do a web search on RTG sometime.
It's a question of weight. No matter how you build them, nuclear Radioisotope Thermal Generators are heavy. This mission was heavily mass-constrained. What they wanted it to do was at the limit of what the rockets were capable of.
Add a several-hundred-kilogram RTG to to mix, and the 'rocket equation' kills you. You just cannot get the probe to the comet. Solar panels were the only option.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
Correct me if I'm wrong, but wouldn't it have been really bad if there had been a boatload of plutonium-238 on the Challenger?
Uh, no.
A boatload of Pu-238 won't explode, and RTGs are designed to stay together even in a launch explosion. If I remember correctly, one RTG was involved in a launch explosion, and it was recovered, refurbished, and used again.
Phil would receive excessive Radiation Poisoning.
Given the hold the leftists and envirowhacks have over public policy these days, good luck building so much as a nuclear powered teapot without getting picketed. This is the "pro-science party", mind you...
http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
"One example is the RTG used by the Voyager probes - 23 years after production, the radioactive material inside the RTG will have decreased in power by 16.6%, i.e. providing 83.4% of its initial output; starting with a capacity of 470 W, after this length of time it would have a capacity of only 392 W. A related (and unexpected) loss of power in the Voyager RTGs is the degrading properties of the bi-metallic thermocouples used to convert thermal energy into electrical energy, the RTGs were working at about 67% of their total original capacity instead of the expected 83.4%. By the beginning of 2001, the power generated by the Voyager RTGs had dropped to 315 W for Voyager 1 and to 319 W for Voyager 2."
Gregory Benford had a great column about this, all the way back in 2000. It also involved a nuclear powered satellite.
It's human nature to react more extremely to new things, especially if they seem "unnatural." This might have been a survival instinct in bygone days, when the hominid who noticed that bush was out of place could take another path and avoid getting eaten by the sabertooth tiger behind it. But like so many such instincts, it translates poorly into the technological era.
Editor Emeritus and Senior Writer, TeleRead.org
The writer of the article didn't do his research. The designers did not expect the instruments to survive the approach to the Sun. So this could not have gone on for years and years.
From: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions "In any case, by March 2015, when the comet is closer to the Sun, it is likely that the lander will become too hot to operate."
We'd have gotten years of pictures of the crack it landed in. A better landing gear would have been a better choice. Technology gets better, remember? Clinging to nuclear power is quite a Luddite thing to do.
Do you power your quadcopters with nicads or lead-acid batteries too?
Move on.
Both fission and radioactive decay are most often used to create heat, which then drives some heat engine or other. The most cheapest and most efficient heat engine people know how to build on Earth is the steam engine.
Occasionally, you can do betavoltaics with beta-decaying isotopes, or use high-energy radiation with some phosphorescent material for lighting.
Hi there, I'm Bruce Halberstadt, the chief scientist involved in the Philae lander design. If only we knew of this option when we were designing our lander!
Would you like to come work for us on the next lander? We need more people like you.
We've been hiring all of the top internet commenters for our next project, I think it's going to be spectacular. I can't confirm it just yet, but from recent meetings, it looks like the next project will be a giant robot that searches for extra-terrestrial boobies, with devices on-board to send back relevant cat videos. With your help, maybe we can make this thing nuclear powered.
Bruce Halberstadt
This has been done to death in a variety of places. An RTG was not used for many reasons such as mass and availability, balanced off against the science experiments that both probes carried. Rosetta was always slated to do most of the experiments, and the landing of Philae was always an unpredictable event (I've read that a matching set of harpoons kept on Earth for the last 10 years in a vacuum also failed to fire).
But think about it. Add an RTG, which adds mass, which means less science overall, possibly to the point of not including a lander. Not only that, you need to oversize the RTG so that when 10 years of zooming around the solar system are up, that it still has enough juice to do the work you want.
The people who designed Rosetta/Philae are rocket scientists, and I am not second guessing their choices. What they have already achieved is phenomenal, and the science has only just started.
I am Slashdot. Are you Slashdot as well?
Np, it would not have mattered.
Numerous times RTG-powered spacecraft had their main rocket "explode" or "fail" and the RTGs were just recovered. Early models, packed without any precautions at all, basically contaminated some small area.
http://en.wikipedia.org/wiki/R...
Then again, if you are worried about RTGs contaminating things, you should probably pull all your hair out over the nuclear weapon tests that occurred and all the stockpiled weapons, ready to be deployed at moment's notice. Weapon testing contaminated ALL soil around the world with detectable amounts of plutonium. Amount of the substance in RTGs is negligible by comparison.
. . . . but I'm not sure how viable Plutonium is as a power source. Most of the spacecraft that use it are quite large and heavy and not designed to land themselves (for instance, the Galileo spacecraft was Plutonium-powered while the lander it dropped was not).
Plutonium is one of the densest substances on Earth and I'm guessing the engine you need to turn heat into electricity is none-too lightweight.
My understanding is that radioactive batteries are only used on heavy, long-term missions where solar power is impractical for legitimate engineering and economic reasons that go far beyond simple public fear. If I am wrong, someone please correct me with good evidence.
Problem is NOT the RTG. Problem is the design choice that the lander should anchor during the first contact. The decision that the lander should land and, if necessary, to jump to better place and only then HEAT it's harpoons and melt the surface would save the day. Only minuscule thrusters are needed for it.
Here on earth our nuclear power comes from fission reactors producing 500-3000 MWt of heat which we in turn attach to a glorified thermal power plant consisting of water moving in a closed loop through pipes and turbines not fundamentally very different than a steam engine. This nuclear power is instead the radioactive decay of a small radioisotope, emitting a mere 500Wt (but with no way to turn it off because no fission is involved) which we in turn attach to a relatively unconventional thermoelectric generator which doesn't require the giant size or any moving parts (except electrons) which a terrestrial thermal power power plant employs.
In both cases you need a heat source (the nuclear fuel, probably ~500K) and a heat sink (either a large body of water at 300K or the outside of the spacecraft which is a cold ~100K because it radiates any heat into the vacuum of space) and generate electricity from the difference.
Mod Parent up Please
Whilst it is an appropriate use of a nuclear power plant, I'm sure the mass of a nuclear powered probe would have increased the costs and complexity of the launch and landing whilst decreasing the science payload.
I think it would have been far easier just to make sure the harpoons *actually* fired. If it was nuclear powered the probe may have just smashed, instead of bounced, the additional mass. The problem wasn't the power source, it was the landing harpoon. We have never landed on an asteroid before and these are, inevitably, the lessons that have to be learned.
The sun is a perfectly functional fusion reactor, so why wouldn't you use it for power? Had a nuclear plant been installed the probe would have had a guaranteed end of life, where as the panels afford the craft the possibility of functioning indefinitely. Had you been talking about a probe set to go well away from the sun then absolutely and pu-238 power plant would be a great idea.
My ism, it's full of beliefs.
nuclear power is as heavy as you need it, if you can't carry the biggest one then you can build one on your desk with something radioactive and one of those desktop Stirling engine toys. Assuming you live in a jurisdiction where you are legally able to own, say, a few tens of milligrams of Po-210, of course (Po-210 emits 150W/g, but has a half-life of maybe a third of a year).
note: Keep Po-210 well cooled. If you keep it near your GPU while you're playing Metro: Last Light, it will become airborne and turn you into one of the mutants.
nuclear? not on a comet in MY backyard
RTGs don't need steam. They work using the theroelectric effect - which you can demonstrate using a copper wire wrapped around a steel nail, connect the assembly to a milliammeter and fire a hot (blue) flame at it.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
heh... that power could run: my laptop, my netbook, my printer, my database server, and my HTPC, with juice to spare.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
In Andy Weir's book "The Martian" our hero is stranded on Mars. He uses his RTG as a heat source when he goes for a long drive in one of his rovers.
so... when was the last time you landed anything on a comet?
Pot, meet fucking kettle.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
Considering that the probe has to maintain workable temperatures, a nice warm nuclear battery would only help that situation.
Now as to that temperature that is only high when compared to the relative temperature that the comet spends much of it's time in, is still rather unimportant. You see, the lander is less than a cubic meter in size. (A cubic meter is 1m x 1m x 1m for those that don't understand volumes.)
Now to snag some dimensions from wikipedia, that comet is comprised of 2 parts, the Large lobe which is 4.1km ×3.2km ×1.3 km (2.55×1.99×0.81 mi), and the Small lobe at 2.5km ×2.5km ×2 km (1.6×1.6×1.2 mi).
Now, worrying about a tiny heat source like that itty bitty probe being hazardous to the comet is also completely ignoring the big giant unshielded nuclear fusion core it keeps getting closer and closer to. That's right, the sun is going to dump far more heat into that comet in one day than the probe and a thousand nuclear batteries could in their entire functional lifetime could.
Though I do wonder if the temperature at the comets solar perigee will ultimately reach, and if it will exceed the probes functional temperature range.
Nuclear power is bad. Exporting radioactive materials to a different country is worse — and a different celestial body is outright horrible.
Solar, on the other hand, is clean and wonderful...
Why can't we here in the US be more like the sophisticated Europe?
Please, don't hate.
In Soviet Washington the swamp drains you.
One downside to RTG (Radio-isotope Thermal Generators) is that radioactive elements decay, and this causes the power output to fall off slowly but continuously. And the probe wasn't deployed for 11 years after launch; it's not something that we can activate on deployment. IF the thing had landed properly, in the sunlight, the solar power would have been fine. It's too bad that it couldn't have carried both, but that would have been a hefty weight penalty at launch.
What could go wrong with launching a payload including nuclear material? Oh, yeah. Rockets exploding at takeoff could be an issue. http://www.cnn.com/2014/10/30/us/antares-rocket-explosion/
Not the same thing. He's not second-guessing the scientists who designed it, he's second-guessing the Slashdot self-appointed experts.
Ignorance killed the cat. Curiosity was framed.
Your lack of knowledge on PU-238 is disappointing...
>Though I do wonder if the temperature at the comets solar perigee will ultimately reach, and if it will exceed the probes functional temperature range. Not likely, the perihelion for this comet is 1.24 A.U. so the probe got more solar heat leaving Earth than it will ever get on the comet. What they are hoping for is that as it gets closer to the Sun it might get enough extra light even in its poor location to charge back up.
And if that comet then hit earth, do you know what a huge catastrophe that would have caused?
Then we would be saying 'ah but couldn't they just use solar power?'
The mass of the Churyumov---Gerasimenko comet is roughly 1 x 10^13kg. Should it ever fall to earth, I wouldn't expect the dispersal of U-238 from an aging Rosetta-class probe to be my biggest concern.
some of them might actually be certified experts.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
This is why we don't have Pu-238 powering more of our probes.
Two of my imaginary friends reproduced once
You're trying to study a temperature-sensitive environment in its natural state. An RTG produces lots of heat. (They are only about 5% efficient, so they produce twenty times as much heat as electrical power.) The presence of the RTG might perturb or destroy the environment you're there to study. I don't have the detailed knowledge to say if this is the case.
Plus the issues others have raised: mass, scarcity of suitable isotopes, and launching highly radioactive material on top of hundreds of tonnes of potentially explosive fuel is something you'd rather avoid if possible.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Why don't they just make two probes which were exactly the same and send the to two different comets at the same time. How much cheaper would the second probe be?
I wonder where there is a break-even whereby it makes sense to send the mechanical stuff ahead but send the computer part on a smaller, faster shot simply due to the power savings and increased processing capacity gained in what would be the time in between the launches.
Well, this just goes to show why you're not involved in building space robots. It's high risk, but high reward. It's a technical challenge. The science payoffs are huge. A large proportion of missions are doomed to failure because we're pushing to the very limit of what we are technically-capable of achieving.
The guy with the shirt wasn't even an issue for anybody important. Matt Taylor was only brought up by an idiot "tech writer" who didn't know how to write about a space mission. He'd literally just been kicked off of a video game website owned by Gawker because the readers were sick of his shit.
If that's the sort of thing that you concentrate on, rather than what a monumental achievement it was to even have the audacity to try this mission, then what you have to say about science and tech doesn't matter at all.
Maybe you should pay Iran to produce some? I've read that they want to learn more about these things.
are demonstrated to, not just designed to.
The team fully expects Philae to get more light early next year. http://www.cbc.ca/news/technol...
You really thought they didn't consider it?
The heat burns off from converting it into electrical energy to power the space craft. Having heat in a power generator is not a problem.
Destiny is what it is and nothing could change it.
No, the parent post was talking about a radioisotope thermal generator that works by using the decay heat to drive a thermocouple and generate electricity.
That would likely not have been a good idea for this tiny lander, because the RTG and the safety devices that would be required by the anti-nucular idiots would have made it unfeasible.
It would have been an absolutely ideal application for a RHU - radioisotope heater unit, that doesn't bother generating electricity - you just attach it to the part you want to keep warm. The problem here is not so much electricity, it's the electricity required to keep it warm enough to survive.
If you heat it directly, it may still go on and off from inadequate power, but it won't die the first time it cools off too much. When it has enough power to run the instruments and charge the battery, then you can get data, and it stays alive the rest of the time. You can get the data later, if necessary - it's not likely to be going anywhere, at least not on purpose.
Due to several sources closely linked with the Rosetta program, Philae will be getting a whole lot of sun come May 2015 due to the position of the comet as it adjusts it's precession around the sun and moves that particular part of the comet in to near-constant daylight. Expect more news at that point from Philae. You heard it here first, folks.
moox. for a new generation.
I get the mission design, and I think most people here get the idea, too. But ESA seems to have missed the boat on the PR and public affairs front.
The demise of the lander after a complete primary mission is being portrayed as a huge failure. As near as I can tell, it did exactly what it was supposed to do for about as long as it was supposed to. Anything beyond that was "if possible".
Additionally, the mission is being shown as a "lander mission" instead of an orbiter with a small lander tacked on. Rosetta is still doing the mission as intended, and most of the objectives are being met very nicely. I see all sorts of comments in the press (and particularly in the European media and media comments section) as another Beagle "cock-up".
I think it's a very nicely done mission that is working very well. It's a shame that it is not coming across like that.
I know I'll be modded down, bu the mission was poorly planned and executed, after 10 years and X amount of dollars to fuck up at the crucial point shows this.
The questions asked are not the ones that should be asked.
"If any question why we died, Tell them because our fathers lied."
Is this all about a treaty between NATO and Russia?
We can't send anything nuclear into the atmosphere.
Thank you Dave Raggett
So, let me see if I understand this... You have a device that needs 32 watts of electricity to operate. You're proposing we power it with an RTG, which are typically only 3% efficient at heat conversion. So that RTG has to produce at least 1.1kW of heat. You're telling me that you want to land a 1.1kW heat source on a body whose surface measures below -70C, and whose surface is made of frozen ammonia, water, methanol, carbon dioxide, and methane. Anyone see the problem here?
"if only it were better designed"
I've gotten used to this sort of armchair quarter-backing, but seriously: this guy can go fuck himself.
They landed on a fucking comet! Better designed? Has this guy even gotten something in to orbit?
Engineers are given requirements definitions, they provide as much input as they can on the various trade-offs so the customer is well informed while making his decisions. Once the customer stops listening to the guidance or makes his decision: the job is normally pretty easy if the requirements aren't impossible to meet.
What fucks projects up is when the decision maker wants to make last minute changes to the requirements during the tail end of the last 20% of the project that takes 80% of the time. Then you get the same penalty as making scrap metal in a machine shop: You're not only 0 parts richer: you're also out 2x the time it should have taken to make the first part + cost of materials and consumables.
It was designed to do a job that no one had done before using technology that seems laughable by today's standards(2004? I think I was still using Lycos as a search engine).
I wish losing my virginity went as smoothly as Philae's landing! I at-least had the benefit of knowing people who had gotten their dick wet before!
They had a tough job to do and they kicked ass. Anyone who wants to say otherwise or steal their thunder can STFU &/or suck a fuck.
I am not a comet expert, but I am a formal logic expert and his use of "a priori" is wrong (he was using it in the sense of "beforehand" when it really means from something previously, or something forming a causal relationship). Take that for what it is. Given that, among others, his questioning of others questioning is questionable. Would have been far better to give reason instead of appeal to authority. It feels even more disingenuous coming from a poster named "Irate Engineer".
... what size RTG do you want to stick on it?
No, it works by turning atoms into other atoms. What you do with the resulting heat and radiation is up to you. Whether you use it to drive a steam turbine, a Stirling engine or a thermocouple is up to you.
Once you get the rocket safely out past Earth's orbit, most of us hippies aren't too worried about it.
The problem is getting it there - what percentage of space launches fail? Way more than zero, and we don't want plutonium-powered reactors on an exploding rocket, even if ETGs really are about as safe as you can get for nuclear power generation.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Why, he's just ranting. Shitload is not a scientific value.
Even were someone a certified expert, they probably haven't worked on the project, and even if they had, they probably don't know the whole of it (budgets, constraints, etc) and even if they did, they probably wouldn't be sitting on slashdot second guessing multi-billion euro projects. Think.
Because nuclear is bad?
Nuclear power is much cleaner than coal, I don't know if Hydro is cleaner (what we have in Quebec), but CANDU reactors are clean (they can burn other reactor's waste).
I really don't understand the fuss about nuclear energy
I've got better things to do tonight than die.
The first is that if something goes wrong on takeoff you risk what is effectively a 'dirty bomb' going off somewhere in the Earth's atmosphere which is not good.
Its not nearly as bad as you think. The biggest impact of a dirty bomb in a city would be psychological.
In the atmosphere, less important.
had better make sure that the craft does not return for Earth for a few billion years otherwise, again, it is like a dirty bomb going off in the atmosphere.
Uh, nuh. Pu238 half-life is 88 years. Here is the most basic clue about radioactivity: radiation intensity is inversely related to halflife. If it has a billion-year half-life, it is barely radioactive at all. A dirty bomb needs something with lots of radiation, and so a short half-life.
Sure, it's designed to not fall apart in an explosion. But what would happen if it would be heated up and worn down in a low angle orbital reentry? It could be subjected to melting/burning temperatures for many minutes. I wouldn't be surprised if that would end up in plutonium dust in a big trail in our atmosphere, waiting for living creatures to ingest it some way....
I was promised a flying car. Where is my flying car?
> we don't want plutonium-powered reactors
Fyi space probes don't reactors. Like the tritium I keep next to my bed, and the isotope in your smoke alarm, it just sits there slowing releasing a little energy. Carrots are the same.
For more fun facts that might interest an environmentally concious person , check out one of Patrick Moore's articles about nuclear energy vs the status quo.
I don't think you realise just how indestructible a nuclear battery is, the one on Cassini was designed to withstand a crash that might have occurred on it's slingshot flyby of earth (fortunately we didn't get to test that claim). Testing is done by firing the battery from an artillery gun directly into a solid steel wall several feet thick. What happened to Antares would have merely burnt the paint off the outside a nuclear battery. Basically the only way to get hurt by one of them is to be unlucky enough to be hit on the head with it.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Dear Irate,
RTGs are not new or cutting tech technology, and it's almost guaranteed they were suggested as a practical source of energy during the engineering phase of the probe. Politics correctly determined it to be infeasible at the time; that does not detract from the worth of the ultimate design of the launched probe. Still - it would still likely have resulted in a superior mission outcome, which is a footnote worth considering for future endeavors.
Tl;dr
Leave the egotistical bullshit out of it and focus on the best way to get the data.
Captcha: pricked
Living creatures are already injesting a lot more radioactive material than few kg of dust in that scenario. If you ever eat carrots, potatos, or other root crops you're injesting far more radioactive material - by several orders of magnitude. Bananas also.
Radiation has been here far longer than humans have. It wasn't scary until The China Syndrome.
Basically the only way to get hurt by one of them is to be unlucky enough to be hit on the head with it.
Having it fall in your backyard and grabbing it by the terminals might tingle a little as well.
How is this possible, a comment with hate and false information is modded "Insightful"? RTG design from the 70s, "SNAP-19", would have been enough for Philae, adding whopping seven hundred GRAMS of extra weight.
The soviets had a series of active radar dish naval espionage satellites, powered not by RTG, but by full chain reaction fission reactors that powered massive thermo-couples for electricity. At disposal times, a small cannon was supposed to loft the PU reactor core from 160km orbit to 900km and then forget about it for 3-5k years. In one case the salute failed and the satellite fall wholesome on Canada in 1979, contaminating vast areas with sheet-film like PU flakes. That's how Santa's reindeer got the glowing nose. CIA being CIA they couldn't miss the chance to collect clandestine info on-site, eventually allowing the red press to blame the "imperialists" of wrong-doing in the case.
we don't want plutonium-powered reactors on an exploding rocket
Back up a bit, who's the "we"?
I recall seeing testing footage for the RTG in the Cassini probe, among other things the tests involved a large artillery gun and a steel wall a few feet thick. Cassini was particularly controversial because it made a 'sling shot' flyby of earth at a much greater speed than escape velocity. From the tests I saw in the doco decades ago the worst thing that could possibly happen with an RTG is that it falls from the sky directly onto someone's head. Far from being anti-nuke, I'm actually interested the idea of "pebble bed" reactors (materials research is what's needed there). I'm also in favour of "full life cycle" nuclear power as practised in some parts of the EU. I don't know of a -science based- environmentalist/hippie/greenie who thinks otherwise. I've held these views since the early 90's, I'm not alone either, James Lovelock and some other influential greenies expressed similar opinions in the early 2000's
I speak to you today as a scientist and as the originator of Gaia Theory, the earth's system science which describes a self regulating planet which keeps its temperature and its chemical composition always favourable for life. I care deeply about the natural world, but as a scientist I consider that the earth has now reached a state profoundly dangerous to all of us and to our civilisation. And this view is shared by scientists around the world. Unfortunately, governments, especially in Europe, appear to listen less to scientists than they do to Green political parties and to Green lobbies. Now, I am a green myself, so I know that these greens are well intentioned, but they understand people a lot better than they understand the earth, and consequently they recommend inappropriate remedies and action. Lovelock 2005.
Disclaimer: According to my parents I became a Hippie back in 1976. Like any other social group, "Hippies" in general are reasonable people if you stop insulting them and feeding them on bullshit.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
...and all this time I thought I was doing nuclear stuff then it turns out I was just the friggin' tea boy.
Except that you are missing the fact that a nuclear battery is not the same think like a nuclear reactor. You can build a nuclear battery with something around a cup full of material, whereas a nuclear reactor needs a significant larger amount of material. Also it is funny how you mention Fukushima, the health effects in this incident where rather minor. There are chemical industrial accidents with significant higher casualty rates than that. If you mentioned Chernobyl you may have had a point, but not with Fukushima.
I guess you haven't heard, but there are actually multiple types of radioactive elements in the universe, and they can even be present in different amounts!
.: Semper Absurda
Or you could read the article (psht this is SLASHDOT, what was I thinking?) and the papers it references which indicate the most likely outcome of an explosion of the craft within 1m of takeoff would still result in 0 deaths. Science, not baseless assertions.
There are the first three Mars rovers - Sojourner, Spirit and Opportunity. Those were all solar powered. However when they realized that dust would cover the cells they then sent up Curiosity and that baby is nuclear. She has an RTG on board.
There are existing RTGs with nearly the same mass to Philae's solar power system. It's not a big secret or anything, you can even read about them on Wikipedia, you know, if you're in to fact-checking.
.: Semper Absurda
>> The biggest impact of a dirty bomb in a city would be psychological.
Yeah, like around fukushima : they all developped psychological cancer, you know...
Who did?
But on the Internet, they're just screen names. So they need to use their expertise, rather than these hypothetical certificates, to back their arguments. Which might not be such a bad idea IRL, either.
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
you are missing the most basic clue that the amount of particles and/or gamma radiation given off is not necessarily the most important factor, but rather the energy of the output. A short half Life alpha emitter is not more dangerous than a long half Life high energy gamma emitter.
It doesn't work like that, it isn't a chemical fuel you can burn or save. The amount of Pu-238 you need is dictated by your peak power demand. How long it lasts is dictated by nuclear physics (the half life of Pu-238.) You have no control over how fast the plutonium is used up.
Couldn't they make a binary RTG, something like: a set of ampules with low-radioactivity fuel that could be induced to undergo fission at accelerated rate under a flux of neutrons, and a separate neutron source to ignite them, placed in the "firebox", enclosed by thermogenerators. When craft needs power, it brings an ampule from the remote (or shielded) magazine into the firebox with the neutron source, so ampule "ignites" and emits heat. After fuel is spent, it is ejected and replaced by a fresh ampule.
Mind you, the neutron source could be e.g. a Farnsworth fusor, therefore completely switchable between on and off states, and able to even be throttled to match needed output power level. But in that case, you would also have to have yet another auxiliary power source aboard, to jumpstart the whole contraption, or otherwise it should be kept continuously on, on at least a low output power. I guess dual system solar/throttled RTG could allow for switching over when circumstances dictate it.
Europe should feel lucky that the enviro-freaks didn't insist the probe was wind powered.
Look, don't start trolling with fukushima. Long-term health effects due to radiation leakage cannot be statistically seen yet. Also, using Wikipedia as a primary info source? Sheesh. I just modified the page, fyi.
Plutonium is not only radioactive, it's also quite highly toxic. Like in the same range of toxicity as nerve gas. Plus it has a "biological half-life" of 200 years, which means one in your body it stays there, Nice, isn't it?
It was looked at and rejected in favour of high efficiency solar cells. At the time of the design of Philae (early-mod 90s?) there were no European designs for an RTG nor any expertise in building them. If the Philae consortium wanted an RTG they would:
- Source it through the US -- you couldn't exact buy them off the shelf and have all the attendant ITAR baggage that would go with it. Since it would practically work as a US contribution to Philae there would be some science exchange in return. Not impossible, but at that time was there any US money to fund a further contribution to Rosetta from the US on what was quite a high-risk project? Not clear... It also goes right against one of the core principles of ESA which is to invest in/support European technology development.
- ... or fund the development of a European RTG; high risk and probably prohibitively costly for the money available to support the mission and meet the mass budget available for Philae. No doubt that mature designs probably do not have a huge mass penalty, but a new design? Who knows, or would want to take the risk?
- There was at the time quite considerable political resistance in certain European countries to RTGs in space. IIRC Germany was one of them and this would have put a big obstacle in the way. Development of solar panel technology was and still is considered an important goal and improved solar cell technology would be an important spin off.
In the end it really does come down to politics; the safety issues could have been mitigated (at some cost), but there was no political will to go in the direction of RTGs. It will be interesting what will be selected for JUICE...
Incidentally Rosetta itself suffers to a certain extent from choosing solar panels - the long array is turning Rosetta into a windmill that is quite difficult to steer. RTGS would have allowed a smaller array.
Please remain calm, there is no reason to pani... wait, where are you all going?
For the price of one RTG, ESA could have built two solar powered landers, which would be much more useful than one that didn't require sunlight.
Uh, nuh. Pu238 half-life is 88 years.
Correct but it does not stop there. It decays into an isotope with a 246k year half life and so on down a decay chain which eventually ends at lead.
"The first is that if something goes wrong on takeoff you risk what is effectively a 'dirty bomb' going off somewhere in the Earth's atmosphere which is not good. "
No you are wrong. RTGs are built to survive any type of booster failure. The RTG on Apollo 13 survived a very high speed reentry. They are constructed of layers of graphite, ceramics, and often refractory metals. The only danger an RTG offers from a booster failure is if it lands on you.
"The second, which does not apply in this case, is that if you make it into space safely you had better make sure that the craft does not return for Earth for a few billion years otherwise, again, it is like a dirty bomb going off in the atmosphere. "
No you are wrong again.
The half life is not all that long on the isotopes used in RTGs and even if one did completely burn up on reentry it would cause less ecological harm than the average European music festival.
Also material that is used is only a few kgs and frankly you can stand right next it unshielded and it would not harm you. Frankly you could put it in your pocket and not be harmed since it an alpha emitter and not gamma emitter like Cobalt 60.
Someone has done a good job of indoctrinating in the proper use of fear words like "dirty" bomb.
Here is a helpful bit of logic about dirty bombs. No military has ever put dirty bombs in to inventory. The reason is that they are really not effective weapons. They just do not do enough damage to be worth the trouble. Also you would never use something like Pu for a dirty bomb because it just is not deadly enough.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
Much heavier. After all, as EVERY nuclear fluffer KNOWS, the rate of decay of plutonium or uranium is REALLY REALLY LOW, therefore ABSOLUTELY SAFE. Thus, unfortunately, it needs to be either extremely heavy, still have batteries or have much lower power production for it to fit in the same payload parameters.
Of course, these do not matter to the armchair theoretician who, with especially acute hindsight, can make up any old shit to make out that solar power is just not an option.
On the lowest end, I saw a project where someone made an nuclear battery using an over the counter tritium keychain and solar panel. Sure it could only power an LED (with less total lumens then the keychain) but had a half life of about 12 years. So there you have an extreme example of just your point.
It is comments like this that make me wish Slashdot had something about +5.
I reckon teh intarwebs would be full of armchair experts spouting a ton of shite.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Wow, and I thought solar people were being pushy here on Earth. You nuculer power guys just never give up. By using solar panels, Philae avoided polluting comet 67P and there is no problem with nuculer waste disposal.
Don't take life too seriously; it isn't permanent.
Nah, I bet the voltage is too low. You'd have to lick the terminals.
eminent
Not even ordinary heat death.
The women already made their eggs. It is the men, who make sperm daily. Their sperm all have 3 eyes and look like Homer, "DOH!"
The original probe can't reflect sunlight on Philae somehow?
I only look human.
My mother is a halfling and my dad is an ogre, so that makes me an Ogreling
Sign me up! I'm going to be Kanye.
I only look human.
My mother is a halfling and my dad is an ogre, so that makes me an Ogreling
You know, all those people who are busy not getting killed by the incident.
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The half life is not all that long on the isotopes used in RTGs and even if one did completely burn up on reentry it would cause less ecological harm than the average European music festival.
Best wacky comparison I've seen in recent memory.
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It' an alpha emitter tat decays into a less energetic alpha emitter.
so scary.
The Kruger Dunning explains most post on
yeah, what's one-or-two extra kilos when you're launching a mission to remotely drop a probe on a comet?
It breaks my pluginses, my precious!
Generally the ways to do both simultaneously don't make just 238Pu but a mix of isotopes, which is not really what you want for RTG batteries. The standard method of 238Pu production is by irradiation of Am.
they landed on a comet. While the science was important, the main goal in my mind, was to prove it could be done. What needs to be done to succeed(i..e are harpoons the best option) etc.
They have now proven it can work, now they can ratchet up the complexity by adding experiments, RTGs.
Except that the mass of the RTGs used in the Voyager programme, which provide far more power than this probe would have required, weighed a grand total of 37kg, including around 4.5kg of 238Pu. A smaller one would have done this probe just fine. In terms of getting to the rocket there's no drama (as long as you can escape the Earth's gravity well); the rest was slingshots and a bit of thruster power. As the total flight payload was 3000kg you're looking at a 1% increase in thruster. Total increase in launch weight probably around 45-50kg, which isn't "right on the edge" of launcher capability.
Doesn't nuclear power work by boiling water?
No, it works by turning atoms into other atoms. What you do with the resulting heat and radiation is up to you. Whether you use it to drive a steam turbine, a Stirling engine or a thermocouple is up to you.
Well, an RTG works by containing atoms that are going to change themselves into other atoms. We call atoms with this property "radioactive". Still, you got the general idea.
Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
The worry with a rocket, of course, is that it might explode in the atmosphere. Dispersing even a "cupful" of plutonium in the atmosphere could have serious consequences, the severity depending upon many different circumstances. That said, I think it's worth the chance for some projects. But people's worries are not unfounded.
-- sudon't
Air-ride Equipped
The real issue was the landing, not the power source. But this ass-hat would have you believe the fault was the power source. Yes if ifs and buts were candies and nuts we'd all have a Merry Christmas. Stop the fucking arm chair quarter backing.
Do the terminals taste good if you lick them?
"First they came for the slanderers and i said nothing."
Don't forget that any computers launched into deep outer space needs to be radiation hardened and that the development of radiation hardened components happens at a much slower rate then consumer products.
https://en.wikipedia.org/wiki/Inverted_totalitarianism
After exhausting its primary battery, it went into hibernation, most likely never to wake again.
Huh? ESA has insisted that they expect it to wake up again, maybe within the next few days and failing that by 2015.
This is slashdot!
We all know that "greens" are responsible for the lack of a safe and scaleable full-life-cycle nuclear fission industry, and that it has nothing to do with huge corporations writing laws that let them do things cheaply and badly!
Don't try and divert the narrative with your "facts" and "proof"! Facts are meaningless - you can prove anything remotely true with facts!
Hippies are the reason that corporations are failing to provide safe nuclear fission. It's hippies dammit! Hippies!
Is a Wt what you get when you divide a Jl by a Sc?
True. But there may still be gains to be had.
It kinda reminds me of a local contractor. He does work all over the US. He gets all the equipment transported to the site well ahead of time then when the work is due to begin, loads all the workers on his private plane and flies them out there.
It's cheaper, the shielding is lighter, gives about the same results, and the press doesn't hate it so much.
However, it doesn't much matter which you'd use, you'd get superior results. Provided things didn't break in the bounce. That was a particularly nasty prang. The yellow flags are out for sure. I wonder if Murray Walker had predicted it would go smoothly.
The way I would have done it would be to have a radioisotope battery that could run the computers and heaters (if any) but not the instruments or radio. Those should be on a separate power system, running off the battery, although I see no reason why the computer couldn't have an idle mode which consumed minimal power specifically to top off the battery.
The reason? The instruments take a lot of power over a relatively short timeframe. Same with the transmitter. That's a very different characteristic from the computers, which probably have a very flat profile. No significant change in power at different times. The computers can also be digesting data between science runs.
Well, that's one reason. The other is you don't want single points of failure. If one power system barfs, say due to a kilometre-long vault and crunch, the other has to be sufficiently useful to get work done. The problem is weight constraints. It's hard to build gas jets that can steer a fridge-freezer through space, but much harder if there's a kitchen sink bolted on. That means less-than-ideal for both power sources, which means if both function properly, you want to match power draw profiles to power deliverable. That reduces sensitivity to demand, which means you can remove a lot of protection needed for mismatched systems.
What we really need is a collaboration with ESA and NASA to produce an "educational game" where you design a probe and lander (ignoring the initial rocket stage) by plugging components into a frame, then dropping the lander on a comet or asteroid with typical (ie: high) component failure rates. Then instead of abstract discussions, we can get an approximation to "build it and see", which is the correct way to engineer.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
They're probably no different from regular battery terminals. Minor metallic taste, nothing special. The taste when wire-cutting with your front teeth is more interesting as you get the plastic overtones. Sniffing molten leaded solder (produces a thick smoke) is also fun. Reminds me a bit of slightly burned cinnamon toast.
I'm not normal, am I?
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
I know a little about this just because a friend of mine is a Materials Scientist, and worked for a company that makes the thermocouple devices that convert the heat to electricity.
He switched jobs recently, and now works for a company that make semiconductor substrates. His old company had gone through several salary cuts and was seeming on the ropes, so he was happy to get into a better situation.
They haven't had much call for these, and their other markets are minor - like generating some electricity from stove flues in remote locations, and those silly little camp stoves that will charge your iPhone.
No fuel source I think is the biggest issue. Doesn't make sense to buy thermocouples when you know you won't have enough fuel to be able to use them.
As others have noted, it's an extremely inefficient conversion process, and takes a lot of space (don't know about weight). It's been used primarily in deep-space probes. I don't think it's likely it would be suitable for a lander.
Should be adopted as a new SI (Slashdot International) unit, along with Libraries of Congress per Second.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
THEY did, you fuckin' retard. Jesus.
When the comet approaches the sun, won't the resident ice be vaporized? Then when it swings away, all the vapor will crystallize again, and the lander will be snowed under ???
There was an incident some years ago very similar to that - a Russian man tried to sell a 'perpetual motion machine' on eBay. He had no idea what it was, it was in the basement when he inherited the house and had been powering the lights for years. Free power, so he wasn't going to question it until he desperately needed money.
Turned out to be an RTG. When the soviet union collapsed a lot of soldiers realised they weren't going to be paid for some time, and a couple of the more enterprising ones managed to steal one. They soviet union used to use some of the most powerful ones built to provide long-term reliable power to remote military bases, lighthouses, navigational beacons and suchlike. When you've that much snow around you don't want to have to haul diesel.
How many have developed any sort of cancer? And what's the expected cancer rate in that population? Specifically, what's the difference between the two?
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
The article says that the lander is only receiving a quarter of the expected sunlight, and thus can't charge enough to wake itself. It doesn't make sense to me why that remaining available sunlight doesn't charge Philae, but just at a slower rate. Could someone please explain why?
Is energy secured from a solar panel not linear in the amount of sunlight received?
If my admittedly weak knowledge of nuclear engineering is what's holding up our space program, methinks we have bigger issues..
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And the most severe outcome of dispersing a "cupful of plutonium" would be what exactly?
Not even close to nerve gas. The most important features of weapon-grade nerve gas is that it is not a gas but fine aerosol in first place, and it works not only when inhaled, but also on contact with skin. Even under these circumstances and with proper military deployment, it is expected to be 10000 doses needed to disable one soldier.
People worked with chunks of plutonium and almost no protection for years, and even minor incidents with chemical weapons tend to leave some wounded and dead. I believe in case of launch failure unburned rocket fuel would be more dangerous than plutonium.
And since you can't find enough of these atoms in nature, you'll need to produce them ... by turning other atoms into these atoms.
Keep in mind that one of the reasons that the health effects were minor are because we are spending a hell of a lot of money keeping them minor.
One of my coworkers is tasked with trying to track and salvage equipment used in responding to the emergency. There are millions of dollars tied up in equipment that has been irradiated. A lot of that equipment is being monitored to get it back to emergency response units as quickly as possible.
http://en.wikipedia.org/wiki/MHW-RTG: "Each RTG had a total weight of 37.7 kg." (...) "Each Voyager spacecraft has 3 RTGs."
http://en.wikipedia.org/wiki/Philae_%28spacecraft%29: "Spacecraft properties: Launch mass 100 kg (220 lb)"
I sense a small problem in using RTGs for ultra-light comet landers there ...
But of course it's easier for the people all over the web to fire knee-jerk responses about anti-nuke tree-hugging hippies etc.
And no, the last sentence was not directed at the parent of this reply, just at the general sentiment showing in many of the replies on this thread.
Thanks that was more or less my goal.
I think we should also make the standard for CO2 be the amount of CO2 used by protestors traveling to a G10 conference.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
Testing is done by firing the battery from an artillery gun directly into a solid steel wall several feet thick.
The half life is not all that long on the isotopes used in RTGs
You do realize that there is a decay chain right? The next one in the sequence has a half life of 246,000 years and it carries on after that ending at some stable isotope of lead.
No military has ever put dirty bombs in to inventory. The reason is that they are really not effective weapons.
Correct. However there is a difference between deliberately trying to destroy something and accidentally doing so. No military has ever used a nuclear power station as a weapon. Are we therefore to conclude that they are completely safe and pose zero risk of contaminating the environment? The question is not whether these things are a deadly weapon the question is whether they are dangerous. Plutonium is also extremely toxic chemically.
Even if these batteries can be made safe enough to launch, and I don't doubt that they could, you have to prove that which will require a considerable engineering effort potentially making them more expensive than the budget will allow. In addition Pu-238 has a very limited supply.
anything done in space is so simple in hindsight-they proved it could be done and done fairly cheaply. Biggest downside is the long time it takes to get the craft to the comet. you could claim this is one of the most complex mission attempted excluding manned missions-how many previous missions ended in epic failure before arrival to the target in space exploration history? And you didnt take politics into it-the nations funding this mission are very anti-nuke they probably never even proposed nuke use because of the politics.
so scary
Yes, there is no way a thin piece of paper would shield against such radiation, you'd need a thick piece of paper.
Alpha particles are actually the most dangerous form of radiation because they are the most highly ionizing and so they cause the most damage to cells. While this also makes them the easiest to shield (even a fair amount of air will stop them) their danger lies from either direct skin contact or from consuming something contaminated by them.
Plutonium: The scary element that helps probe space's secrets http://www.bbc.com/news/magazi...
Casteism
Ha ha, seconded.
Unity? Screw that: XFCE. Slashdot Beta? Screw that: SoylentNews. Australis? Screw that: Pale Moon. UX developers DIAF
The trouble comes when misguided people lacking knowledge about a certain subject nonetheless put a voice to their baseless fears. When considerations are made, their voice is given undue audience. Regrettably in a democracy, the vote of the idiot and the savant are given equal measure. In comparison to the later, the former seems to suffer no lack of abundance.
Two of my imaginary friends reproduced once
For something like a manned mission to Mars, that would be the way to go. For an unmanned mission to a comet, it would be hard for the robot to interface with stuff that hadn't even been designed when it was launched so wouldn't work out so well.
ps Slashdot sure seems to be getting slow at mailing notices of replies to comments.
https://en.wikipedia.org/wiki/Inverted_totalitarianism
Dude, I thought that the heat couldn't dissipate through the vacuum of space. There's no "fear" about it. It's a technical question.
And, as has been said before, the best solution to incorrect facts is correct facts.
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It's an extra 500 grams to use a RTG from the 1970s. So in fact, there would likely have been no extra mass to carry with a modern RTG.
The considerations leading to solar over RTG were 1) the (lack of) experience of the ESA with RTG technology after NASA left the project, 2) the silly political optics of "nuclear" anything, 4) cost and 3) the ultimately limited scientific goals of the lander component, which made the possibility of a 60 hour run time an acceptable risk. How much of a role each of these considerations played is known only to the design team...
.: Semper Absurda
Well, first of all, Philae would NEVER give "years of data". It is clear that Philae will die of heat when approaching the sun.
Furthermore Plutonium-238 generators are quite have - so please think of the payload. Furthermore the insruments need shielding against the Plutonium radiation. Increasing the weight and/or the dimensions of the lander (see the long arm of the Voyager probes).
I am not a designer of space probes. But I'm not quite sure wheter a Pt-generator would have been such a good idea.