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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.
Doesn't nuclear power work by boiling water? Doesn't it require that steam then turning back to water?
On the asteroid, I suppose you could use it as a giant heat sink (yay, destroying the thing we happen to be studying. That turns out well). But during the 12 years it took to get there, how would the heat bleed off? Emitting via radiation requires high temperatures that seem to make getting power via temperautre difference impossible.
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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?'
I don't know if the guy with the shirt had a role in the flawed design of the Philae lander, but if I were an EU minister responsible for allocating resources to these people I'd be pretty upset right now.
They mess up the design of this thing's ability to land on the asteroid after it costs a huge amount of money and travels billions of miles, and then this jerk with the shirt is parading in front of cameras and giving interviews like a moron.
All I can say is NASA are much more professional than this and still outrank the ESA by far.
...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?
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...
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.
...how to land a probe on a comet. Not. OK, let's start shooting holes in the OP ignoramus'suggestions: Q: "But, RTG!" A: Umm, no, fuck RTG. That is a shitload of mass that the mission simply can't afford. Given that no one (even Slashdot ignoramuses) knew a priori what to expect at the comet surface, cheap and simple solar panels made the most sense. Q: "But, harpoons didn't work!" A: Yes, but no one (even Slashdot ignoramuses) knew a priori what to expect at the comet surface. Even if the harpoons worked, no one would really know if that was an advantage or disadvantage, Bottom line, the average Slashdotter has not designed and deployed a space probe onto a comet surface. So, unless you have, and have the data to prove it, fuck you all and leave the science to the scientists, m'kay script-kiddies? Rocket science is hard, even harder than do loops. Try to wrap your heads around that.
Left MS Windows for Linux Mint and never looked back!
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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.
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
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
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.
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
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?
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?
Destiny is what it is and nothing could change it.
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?
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.
I was ignorantly assuming that they'd do everything they could to insure the accomplishment of the mission.
They almost certainly did within the allowed budget. There are two problems with nuclear power spacecraft. 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. 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.
Clearly deep space missions like this mean that there is no chance of return but you still have the risk of a disaster on launch which is not entirely uncommon as the recent Antares Rocket launch showed.
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.
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.
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.
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
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.
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.
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.
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.
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.
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
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.
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.
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!
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)
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.
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 ???
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?
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.
Plutonium: The scary element that helps probe space's secrets http://www.bbc.com/news/magazi...
Casteism
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.