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Space

Helium Depleted, Herschel Space Telescope Mission Ends 204

Posted by timothy
from the say-goodbye-in-a-squeaky-voice dept.
AmiMoJo writes "The billion-euro Herschel observatory has run out of the liquid helium needed to keep its instruments and detectors at their ultra-low functioning temperature. This equipment has now warmed, meaning the telescope cannot see the sky. Its 3.5m mirror and three state-of-the-art instruments made it the most powerful observatory of its kind ever put in space, but astronomers always knew the helium store onboard would be a time-limiting factor." Reader etash points to a collection of some infrared imagery that Herschel collected.
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Helium Depleted, Herschel Space Telescope Mission Ends

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  • Orbital pickup truck (Score:5, Interesting)

    by mabhatter654 (561290) on Tuesday April 30, 2013 @07:47AM (#43589503)

    If only we had a plan for recurring orbital missions... A "space pickup" that would launch on a regular basis to make pit stops for things like extra helium.

    To think how many multi-decade projects like this will "rot on the vine".

    • by Anonymous Coward on Tuesday April 30, 2013 @07:52AM (#43589533)

      It'd have to be more than orbital. Herschel is out at Earth-Sun L2. That's not exactly a short trek.

    • by Anonymous Coward on Tuesday April 30, 2013 @07:55AM (#43589547)

      A pickup truck that can get to L2 and back. Whatever you're thinking of, it isn't the shuttle.

      • by TWiTfan (2887093) on Tuesday April 30, 2013 @08:07AM (#43589667)

        Hey, Bruce Willis and James Bond taught me that the Space Shuttle can go anywhere!

        • by MightyYar (622222)

          In "Footfall" they strap the whole fleet of shuttles to a single nuclear rocket and use them as fighters against alien invaders.

          • If I remember correctly, it’s 100s of nuclear bombs under a battleship. Space Shuttles are then strapped on like fighter jets. (A single nuclear bomb might have enough force to send a space shuttle to orbit, but I am not sure if a space shuttle has sufficient structural integrity to survive. You want a lot of mass for a ship like this. )

            A bit off topic, but have we had the Freeman Dyson interview yet – the guy who came up with this idea?

      • by DragonTHC (208439)

        more of a sailing vessel with a significant hold.

        We will also need an orbital platform capable of storing the materials.

      • by wagnerrp (1305589)
        What about a pickup truck with an extra JATO bottle?
      • Ok, what about Buck Roger's Deep Space Shuttle?. We were supposed to launch that in 1999... Like 20 years after the ones we just retired.

    • by Alex Pennace (27488) <alex@pennace.org> on Tuesday April 30, 2013 @07:58AM (#43589587) Homepage

      If only we had a plan for recurring orbital missions... A "space pickup" that would launch on a regular basis to make pit stops for things like extra helium.

      To think how many multi-decade projects like this will "rot on the vine".

      The Herschel Space Observatory is 1,500,000 km away at a Lagrangian point. Servicing missions of any kind are out of the question.

      • by mrsquid0 (1335303) on Tuesday April 30, 2013 @08:12AM (#43589707) Homepage

        The Earth-Sun L2 point is out of reach with the old Space Shuttle, but the original point is a good one. It is too bad that we do not have the capability to repair and restock the consumables on spacecraft in the inner Solar System. It has been nearly 45 years since we first went to the Moon. We should be able to move around in our band of the Solar System by now.

        • by Megane (129182) on Tuesday April 30, 2013 @08:55AM (#43590137) Homepage

          It has been nearly 45 years since we first went to the Moon.

          We only went there because of a super stretch effort that went to the limits of our technology and budgets. It was an anomaly in the progression of space exploration, and the extreme effort involved probably even set us back by a couple of decades. We are currently on a more normal progression of space exploration, with the possible exception that we (the western world, as opposed to the Chinese) may bypass the moon this time around because we've already been there and it's not really very interesting.

          Actually, I'm surprised that we've sent hardly any robotic missions to the moon in the past 45 years. There's a lot less need for humans when communication delays are only a few seconds, and maybe we could find out something interesting enough to want to go back there.

          • Just send a super model. Hundreds of thousands of men will start searching for ways to get there.

            Better yet - get Avon to hint to the world that moon dust is the new wonder ingredient in the fight against aging. Instead of the men, millions of women will be racing to the moon!

            • by wagnerrp (1305589)
              So the scientists are telling me that rubbing myself down with moon dust was a bad idea... and that I now have cancer...
              • That reminds me of a story -

                Some woman had joint pains. Someone told her that WD-40 would help to ease the joint pains. Instead of asking "how much", or doing any research, the woman supposedly BATHED in a tub of WD-40.

                I really don't know how true the story is. My wife told it to me, she swears it's true, yada yada yada . . .

                Anyway, please, when you get your moon dust cosmetics, follow the guidelines that Avon and Maybelline publish and distribure with every 3 gram bottle they sell.

                • by trazom28 (134909)

                  http://www.snopes.com/inboxer/household/wd-40.asp [snopes.com]

                  They reviewed the list with the company.. arithritis is not on the list as far as I can see.

          • by thrich81 (1357561)

            "the extreme effort involved probably even set us back by a couple of decades" -- I've heard that more than a few times. While it sounds plausible, it often seems to come from either the (dwindling few) old timers who thought we could go to space via the X-15 and later spaceplanes (seems unlikely in retrospect), or from NASA apologists trying to excuse the stagnation there since the ISS and STS ate up the budget for real exploration -- not to assign you (parent poster) to either class. In any case the ST

          • Re: (Score:3, Interesting)

            by Anonymous Coward

            It was not really an anomaly, it has happened time and time again.
            Columbus might have 'found' the Americas for Europe, but people had voyaged there by ship many years prior. There was quite a large gap between when knowledge of the Americas and the ability to get there and back was established and when full exploration and settlement/trade happened.
            The same thing also happened with Euro-China trade, with Rome and the northern areas of Europe and the British/Irish isles.
            Same with ocean floor exploration, Ant

          • by Microlith (54737)

            We are currently on a more normal progression of space exploration

            Normal? Relative to what standard?

          • I don't think the moon stretched our technological limits by any means. All the basic technology required for a moon landing existed before the goal was announced - no new and revolution computer or rocket design required. It was more of a project-management problem - how to engineer rockets powerful enough, how to ensure reliablity, how to guarantee the trip went off without a hitch. The decade from announcment to landing was spent training people and figuring out how to build bigger.
            • by demonlapin (527802) on Tuesday April 30, 2013 @02:01PM (#43593419) Homepage Journal
              At the time of Apollo, the program was consuming half the IC manufacturing capacity of the entire world. The ships were essentially all one-off constructions built by hand. Go read How Apollo Flew to the Moon [amazon.com]. Yes, the physics of it were understood. Yes, as experience showed, we had all the technological pieces to make it happen, in much the same way that we almost certainly could conduct a manned mission to Mars if we really wanted to. But doing so required an enormous amount of blood and treasure.
        • Unfortunately, despite decades of wishful thinking, the laws of physics haven't changed much in the decades since we went to the moon.

        • Re: (Score:3, Interesting)

          by Runaway1956 (1322357)

          We pissed away more than two decades with that stupid ass "space plane" thing. It's like America said, "Well, we were the first on the moon - we'll never beat that, so we'll just give up now. Oh - launch that space plane thingy occasionally, to give lip service to exploration and research."

      • by jekewa (751500)

        Robots? I'm sure the limiting factor is that no one considered sending unmanned missions with supplies. Surely something akin to refueling USAF planes in flight could have been considered and a giant "put it here" port could have been exposed for injecting more Helium as needed.

        To be fair, unmanned drones weren't as good as they are now when the telescope was launched, so it probably seemed much more impossible than I think it might seem today.

        • by xhrit (915936)
          I am pretty sure the telescope itself fits the definition of an unmanned drone.
        • by MBGMorden (803437)

          Any robot that could go out that far is going to have to be pretty sophisticated - to the point that its probably cheaper to just build and launch another telescope (and then we get to benefit by replacing it with a better one).

        • by X0563511 (793323)

          Even today that would be incredibly difficult. It would have to be nearly (if not totally) autonomous because of the communications delay.

      • by mpe (36238)
        The Herschel Space Observatory is 1,500,000 km away at a Lagrangian point. Servicing missions of any kind are out of the question.

        A robot tanker resupply is rather different from the kind of EVA service performed on the HST.
    • If only we had a plan for recurring orbital missions... A "space pickup" that would launch on a regular basis to make pit stops for things like extra helium.

      To think how many multi-decade projects like this will "rot on the vine".

      I'm going to assume due diligence was done and that with it being so far away, a refillable port and a small, single-use robotic craft to accomplish that would be more expensive than just creating a newer satellite to replace it.

    • by h4rr4r (612664)

      Too bad the last space pickup we had was a dangerous rusty heap of crap.

  • See? See? (Score:4, Funny)

    by pushing-robot (1037830) on Tuesday April 30, 2013 @07:47AM (#43589509)

    I'll bet you feel stupid for filling all those party balloons last week.

  • by gblackwo (1087063) on Tuesday April 30, 2013 @07:58AM (#43589583) Homepage
    That's my nitpick of the day.
  • They knew at some point helium will be gone and the telescope will become useless. It ran for four years more or less. Not as bad as the summary made it sound like.

    They are in deep space, so they have an infinite sink at nearly zero deg kelvin. It should be possible to design a closed circuit cooling system that just uses energy from solar panels to pump the refrigerant. But in space applications the weight of such a system of compressors, radiators and pumps might prove to be prohibitive. Still feel sad

    • Looks like the reliability concerns were the reasons why they did not use an active cooling system, not weight.
      • by DarthVain (724186)

        Still, might fail, seems better than, will fail. I guess the risk/reward is: "What are the odds of it failing within the first 4 years?"

        I would have to think part of the problem is having to insulate electronic components against hard radiation, while at the same time trying to cool them.

        You would think the best method would be simply to use a peltier with a big ass heat sink protruding into vacuum. Zero moving parts, no liquid coolants. Then again, ultra low temperature might be hard to hit this way, depen

      • by Megane (129182)
        I'm sure that an active cooling system wouldn't have been vibration-free either. Telescopes don't work so well when you keep bumping them around.
    • by kav2k (1545689) on Tuesday April 30, 2013 @08:07AM (#43589659)

      It's not exactly an efficient sink, is it? Your only option for heat transfer "outside" is infrared radiation, since vacuum does not exactly support conduction/convection.

      • by Rich0 (548339) on Tuesday April 30, 2013 @11:33AM (#43591863) Homepage

        It's not exactly an efficient sink, is it? Your only option for heat transfer "outside" is infrared radiation, since vacuum does not exactly support conduction/convection.

        If you really want liquid-He temps, then you can't really radiate heat to lose it. At 1 atm it is almost as cold as the cosmic microwave background, and probably colder than the inner solar system. If they're running below 1atm then it is probably colder than the microwave background itself. This means that your radiator will only serve to warm up the spacecraft, not cool it off.

        For an IT analogy - how large a heat sink do you need to cool your PC in an oven? The only way to cool under such conditions is using active technologies, like phase change, or maybe Peltier. Since you're fighting entropy, this will ultimately require some source of energy, which will always be depleted eventually in a closed system.

    • by mmcxii (1707574) on Tuesday April 30, 2013 @08:08AM (#43589671)
      Another problem with the system you mention is that heat doesn't radiate away efficiently in space. While such a system may be possible I'm sure that the up-time of the scope would suffer greatly from it.

      Do we have any thermal dynamic geeks here with something a bit more insightful?
      • Thanks, I did not realize things are different in space. So how would one design an active cooling system to dissipate heat in space?
        • by fuzzyfuzzyfungus (1223518) on Tuesday April 30, 2013 @08:51AM (#43590103) Journal

          Thanks, I did not realize things are different in space. So how would one design an active cooling system to dissipate heat in space?

          I am not a rocket scientist; but my understanding is that the space-equivalent of a 'heatsink' is a fin, with a surface that approximates a black body as closely as engineering constraints allow, aligned so that as much surface area as possible(the flat faces) receives as little incoming light as possible, with as little as possible exposed to the sun(so, in practice, the alignment is pretty much the opposite of a solar panel, where you want as much surface area getting sunlight as you can and as little being wasted by facing into deep space as you can). Depending on the orbit, and whether your thermal load is constant or can accept variations, this may or may not require the fins to move.

          If you need active cooling(as you probably would here, since ultrasensitive IR hardware generates some heat on its own and works less well for every additional kelvin) you use a heat pump of some sort, just as on earth; but your 'sink' is thermal radiation from the fins, rather than conduction from the fins into the atmosphere or coolant water.

          The real problem(in addition to the fact that solid-state heat pumps are miserably inefficient, and ones with moving parts have mechanical levels of reliability in an area where you can't just schedule a tech visit), is that thermal radiation alone is miserable compared to conduction/convection into air, which is weak compared to conduction into forced air.

          If you have a large enough payload budget, it isn't necessarily insurmountable, all it takes is more surface area radiating heat; but the engineering challenges of having a cryogenic heat pump capable of keeping the instruments at liquid helium temperatures and enough fin surface area to dump the waste heat from both the instruments and the heat pump's own inefficiencies are significant.

          Liquid helium isn't cheap, and relying on a consumable cuts mission lifespan; but "just let the helium boil off where you need things to be colder" simplifies the engineering considerably.

          • Re: (Score:2, Informative)

            by Anonymous Coward

            Well, put, but one other major killer ... There are no "good" ways to get rid of vibrations on a spacecraft. There's no atmospheric drag (see the mythbusters on the flag on the moon). You basically have to have a damper attached to a mass that kind of sort of slowly adsorbs the energy, re-radiating it as heat. However, most materials are very linear in compression and tension at their minimum range, so it just doesn't work well. Bad enough trying to point a terestrial comms satellite. Absolutely mission kil

            • I hadn't thought of that; but that would make most, if not all, mechanical refrigeration options a bit problematic... And I suspect that the guys over in 'Elastomeric Polymers' just give you nasty looks when you say things like "Do you have anything that works at ~cosmic background temperature, and doesn't outgas in hard vacuum?"

        • Thanks, I did not realize things are different in space. So how would one design an active cooling system to dissipate heat in space?

          Well, if you have a big ol' tank of liquid helium, you could slowly boil that off...

        • by Overzeetop (214511) on Tuesday April 30, 2013 @09:26AM (#43590455) Journal

          You're limited to radiation, and the cosmic background temp, but that's the only limit. Although inefficient, peltier coolers can be used - the advantage is there is no fluid. Heat pipes are the most common form of heat transport, allowing the evaporation of a liquid in a sealed tube to migrate to the radiator end.

          One challenge is the temperatures you're trying to work with. Remember that the temperature of the universe isn't actually 0K, but more like 3K. Liquid helium needs to be 4K or less. That's a slim margin, and at those temps the heat transfer rate is very, very low.

          I clicked on the story because I was an engineer involved in the Superfluid Helium On Orbit Transfer (http://istd.gsfc.nasa.gov/cryo/SHOOT/shoot.html) research project back in the early 90s. If you get Helium just above absolute zero, it loses it's viscosity (like a superconductor loses it's resistance). That makes it far easier to transfer the fluid from a storage container/refueling dewar to a spacecraft in service.

          I actually like radiative heat transfer - it's very straight forward, much like conduction. Convection problems make me cry.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      Actually, strangely the inverse is true.

      In space, there are very few particles, which means that heat transfer is almost non-existant when away from the atmosphere. This causes a problem in that if you generate any heat, it dissipates extremely slowly, which was why the Helium was important. If this piece of equipment was in the sun, it would have been even worse.

    • by IndustrialComplex (975015) on Tuesday April 30, 2013 @08:20AM (#43589775)

      They are in deep space, so they have an infinite sink at nearly zero deg kelvin.

      What exactly could it 'sink' that heat into? While we consider space to be 'cold' the reality is that it is less 'cold' and more 'generally won't make things warm.'

      The vacuum is both a benefit and a problem. When you want to keep things a certain temperature, the vacuum is great as you don't have to sorry about convection/conduction altering the temperature. But when you want to cool things off, that vacuum is a problem because you can't use convection/conduction to remove that heat from your system. You can certainly move the heat from one part of your system to another part of your system, but it takes a long time to take that heat OUT of your system.

      You would have to move the heat to a massive radiator and wait a long time for it to cool due to radiation. Whatever you are using to move that heat will have to work the entire time, (and may have to be cooled as well!). Even then, the temperatures involved mean that such a process would take a very long time to get as low as they needed to conduct the experiments.

      Don't think of space as cold, think of space as very effective insulation.

      • by Twanfox (185252)

        What, you mean there's a reason we sometimes use vacuum insulation in our hot/cold thermoses? Scandalous ;).

    • by xiox (66483)

      The forthcoming ASTRO-H [isas.jaxa.jp] X-ray observatory mission will have a cooling system that will be able to run without coolent. The X-ray microcalorimeter detectors must be cooled down to 50 mK in temperature. ASTRO-H should be launched in 2014.

      • According to NASA [nasa.gov] it will still last just three years.

        "The instrument utilizes a multi-stage cooling system that will maintain the ultra-low temperature of the calorimeter array for more than 3 years in space."
        • by xiox (66483)

          The minimum design lifetime isn't the actual lifetime of the mission. I believe there is enough helium for three years, but the multistage cooler is designed to be able to run in the event of coolant loss. ASTRO-H replaces ASTRO-E2 which suffered a catastrophic coolant loss. There are more details here [harvard.edu], but it's behind a paywall.

    • by tgd (2822) on Tuesday April 30, 2013 @08:27AM (#43589843)

      They knew at some point helium will be gone and the telescope will become useless. It ran for four years more or less. Not as bad as the summary made it sound like.

      They are in deep space, so they have an infinite sink at nearly zero deg kelvin. It should be possible to design a closed circuit cooling system that just uses energy from solar panels to pump the refrigerant. But in space applications the weight of such a system of compressors, radiators and pumps might prove to be prohibitive.
      Still feel sad such a fine piece of machinery is rotting away. Well, may be a better design next time.

      No, they have near perfect insulation. The only heat they can get rid of has to happen by radiating it away.

      Go step outside.

      Notice how warm it is in the sun?

      There's no way you can radiate much heat if you're in direct sunlight -- that's why the space shuttle flew upside down in orbit. It kept the heat shield towards the sun, so it had a chance to radiate heat away from the other side.

      "So, put a big sun shade and block the sun", you might say... well that's easier said than done, the solar wind would apply a lot of pressure to it, and (for that matter) the solar wind itself is well above the operating temperature of the telescope.

      But by all means, I'm sure you're smarter than the experts to designed it.

      • by chihowa (366380)

        There's no way you can radiate much heat if you're in direct sunlight -- that's why the space shuttle flew upside down in orbit. It kept the heat shield towards the sun, so it had a chance to radiate heat away from the other side.

        I doubt that's the main reason why the shuttle flies upside down. The bottom of the shuttle is also black, while the top is white. From a simple light-absorption-radiation point of view, this configuration would lead to heating of the shuttle as a whole. The heat shield is designed to shield from heat conduction due to superheated compressed air in contact with the shuttle during reentry. Shielding from radiative heating makes use of reflective surfaces like what satellites are coated in.

        It seems the shuttl

        • by tgd (2822) on Tuesday April 30, 2013 @10:15AM (#43591003)

          I doubt that's the main reason why the shuttle flies upside down. The bottom of the shuttle is also black, while the top is white. From a simple light-absorption-radiation point of view, this configuration would lead to heating of the shuttle as a whole. The heat shield is designed to shield from heat conduction due to superheated compressed air in contact with the shuttle during reentry. Shielding from radiative heating makes use of reflective surfaces like what satellites are coated in.

          It seems the shuttle would fly upside down to aid in radio communication with the earth, allow viewing of the earth through the windows (a human concern, but still an important one), and to protect the shuttle from earthbound debris (though I'd think the heat shield is the last thing you'd want to damage before attempting reentry).

          Your doubt is misplaced -- that is precisely why it flew that way. The shuttle's radiators were on the inside of the cargo bay doors. The shuttle had a limited time, once on orbit, to get positioned and get the doors open because of the heat build-up.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      Some parts of Herschel's detectors had to be chilled to 0.3 K, others to 1.7 K. There's no way to get that low with radiative cooling; indeed, it's below the temperature of the cosmic microwave background. Virtually all known materials except for helium freeze solid at those temperatures; no standard refrigerant can do it.

      The only technologies we have that can get that cold are all based on liquid helium, and they inevitably lose trace amounts of it over time. They could have given it a bigger dewar vessel,

    • by delt0r (999393) on Tuesday April 30, 2013 @08:42AM (#43590005)
      Radiating heat goes to the 4th power. So at 273K (0C) a panel in space radiates 314 watts per m2. However at 4K we radiate a mere 14.5 micro watts. So to radiate 1 watt we would need a square panel 262 meters a side (69000m2). Even worse space is radiating the same amount of heat back at you. So you in fact would not get rid of any heat. In fact i think this particular system needed to be colder than 4K. So no passive system can do it.
    • by arkhan_jg (618674)

      The problem is also the heat sink. Without convection and conduction, you're left with heat radiation, which is pretty damn slow. Worse, any such heat sink would actually pick up more heat due to being in direct sunlight - the existing solar shield on it to protect the instruments was at 400k! Would depend on the design, but I imagine it would be tricky to even break even against solar heating - that's a lot of energy headed your way all the time (and solar panels only convert a small part of it). So if you

    • There are two problems with your approach: one, the near vacuum of space does not allow for effective cooling via convection. Two, compressors only displace heat, and in doing so they actually generate more heat overall. A good example of this is the coils on the back of your refrigerator, which get quite warm during operation. Your kitchen warms up slightly while the interior of the fridge cools. In space, this heat does not dissipate readily and would build up until the system overheats.
    • by Rich0 (548339)

      They are in deep space, so they have an infinite sink at nearly zero deg kelvin.

      The word "nearly" isn't nearly good enough for this kind of application. If you want a mirror to operate at 1K, then you need to radiate heat to something colder than 1K if you passively cool it. Your infinite heat sink is considerably warmer than this.

      Think about it - you want to take pictures of stuff that is only slightly warmer than deep space. To do so your mirrors have to be much colder than deep space otherwise you'll just get a picture of your mirror. It would be like trying to take a picture out

  • by TWiTfan (2887093) on Tuesday April 30, 2013 @08:05AM (#43589639)

    Know that you always warmed my heart.

  • Salvage Rights (Score:5, Interesting)

    by jdigriz (676802) on Tuesday April 30, 2013 @08:12AM (#43589713)
    SpaceX should go after it and salvage it robotically for use as a solar thermal concentrator. 3.5M mirrors that are already in space don't exactly grow on trees. A simple high-efficiency Ion engine (Dawn-class)and a robonaut should be able to handle the job. They can then lease the asset to Planetary Resources or whoever wants to do industrial experiments. Doesn't have to be quick. Cheap and slow is the way to go here.
    • by Thud457 (234763) on Tuesday April 30, 2013 @08:28AM (#43589855) Homepage Journal
      Andy Griffith says "finders keepers".
    • + 1 for a great idea (never have mod points when i need them!!)

      Seriously; you should approach them on this.
    • It won't be easy to disassemble it and pull the big mirror out of its guts, and then replace the smaller mirror at the focal point with whatever energy collection device you want to use. I'd say you'd need a robot that's as dextrous as a human before attempting this. And then you would have launched that thing to go to the telescope, disassemble the satellite, collect the big mirror and possibly take it to where it's needed, instead of just launching a big mirror...

  • Bit of a shame no one thought to make this a rechargable system.

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      They did think about that.

      But it's a million and a half kilometres away. A robotic service ship to catch and refill it after four years would cost more than just sending up a second, newer-generation telescope.

  • by Quakeulf (2650167) on Tuesday April 30, 2013 @08:28AM (#43589865)
    That reminds me of a puzzle!
  • Helium Depleted, Herschel Space Telescope Mission Ends

    I know that feeling.

  • is quite befitting. had i spent a decade at -269C, id certainly appreciate moving to an orbit around the sun.

    its also worth nothing that in 2018, barring congressional shit-fits or another bush in office, the James Webb telescope is due to launch!
    https://en.wikipedia.org/wiki/James_Webb_Space_Telescope [wikipedia.org]
    • by decsnake (6658)

      yup, and JWST incorporates a bunch of the pie in the sky ideas that have been floated in this thread like a giant sunshade and mechanical cryo-coolers.

  • by wcrowe (94389) on Tuesday April 30, 2013 @10:43AM (#43591285)

    I do know how it works and all, but still, I find it kind of ironic that the Herschel Space Telescope is bricked for lack of the second most abundant element in the universe.

    • Re: (Score:3, Interesting)

      by JBMcB (73720)

      The main problem is the vast majority of the universe is empty, and the vast majority of the helium in the universe is millions of degrees hot.

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