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Space Science

For ESA's Herschel Mission, the End Is Near 40

Trapezium Artist writes "The European Space Agency's far-infrared space observatory, Herschel, will soon run out of its liquid helium coolant, ending observations after more than three years of highly successful scientific operations. Predictions by ESA engineers are that Herschel will run out of helium later in March, at which point its instruments will warm up, rendering them effectively blind. Herschel was launched in 2009 along with ESA's Planck satellite to the Sun-Earth L2 point, roughly 1.5 million kilometers from Earth. At that location, the Sun and Earth remain along a more or less constant vector with respect to a spacecraft, meaning that it can cool to very low temperatures behind a sunshield. At such a large distance from Earth, however, there is no way of replenishing the coolant, and Herschel will be pushed off the L2 point to spend its retirement in a normal heliocentric orbit. With the largest monolithic mirror ever flown in space at 3.5 meters diameter and three powerful scientific instruments, Herschel has made exciting discoveries about the cool Universe, ranging from dusty starburst galaxies at high redshifts to star-forming regions spread throughout the Milky Way and proto-planetary disks of gas and dust swirling around nearby young stars. And with an archive full of data, much of it already public, Herschel is set to produce new results for years to come."
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For ESA's Herschel Mission, the End Is Near

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  • "dusty starburst galaxies"

    Did anyone else misread the headline as ESA Hershey Mission

    • "dusty starburst galaxies"

      Did anyone else misread the headline as ESA Hershey Mission

      No, I read: extra Herschey mission

  • is it going to run out of coolant in march and be "rendered blind" or is it going to produce new results for years to come"
    • Re:so.. (Score:5, Interesting)

      by game kid ( 805301 ) on Wednesday March 06, 2013 @04:06AM (#43090023) Homepage

      Herschel probably won't be able to gather new sights and data once blind, so any "new results" would come from further examination of what it has already seen.

      Scientific instruments these days tend to generate more data than can be quickly processed, so there's probably a lot of images that still haven't been more than glanced at...and if scientists decide to take a second look at what they've already pored over, they can uncover some fun new objects with strange parallax or whatever.

      • by BTWR ( 540147 )
        Exactly. New discoveries from Voyager were made well into the 80s and 90s by looking at the reams of data that had been sent back earlier.
      • Nature tends to generate more data than can be quickly processed

        FTFY. I would even amend that to "be quickly processed, or even stored". Think about a fluid dynamics simulation for instance. Say you want to store a velocity vector at each grid point on a 400x400x1000 grid at 500 time increments. How much harddisk space will you need? A quick calculation comes out at 1.8 terabytes of data! And that's just for the velocity field, you can easily triple that number in a realistic CFD case.

    • Re:so.. (Score:4, Funny)

      by j00r0m4nc3r ( 959816 ) on Wednesday March 06, 2013 @10:39AM (#43092255)
      i always thought it was just an old wives tale that if you release your coolant you go blind..
  • when you lose spacecraft because they run out of consumables. What could we have learned if we'd had continuous IR coverage since the launch of IRAS in 1983, instead of a couple of missions each 1-3 years long?

    • It's no different than any other remote site science expedition. Great effort is made to ensure that Antarctic stations are supplied with consumables, oceanographic vessels come home when then they run low/out, etc... etc... Even fixed installations like LHC have ongoing logistics needs, like an on-site cryogenic plant to ensure a steady flow.

      Logistics (and it's handmaiden, maintenance) are something all scientific equipment needs to deal with. Space isn't special.

    • by sycodon ( 149926 )

      I seems to me that NASA has all the technology needed to create a spacecraft, manned or unmanned, to make accessing the local solar system (Earth, moon, etc.) a matter of routine. Perhaps if they had an appropriation that lasted for more than a year and they (Administration, Congress, NASA) stopped canceling things when they reach 75%-80% completion.

      • Often when the projects are 75%-80% from completion, they are already 200%-500% over budget. Poster child -- JWST. Poster child #2 -- Constellation, though it didn't get close to 75% completion. How far do you let a rogue one go before you pull the plug as it eats up the funding for the other, possibly better managed, projects?

        • by sycodon ( 149926 )

          So instead of fixing the project, you kill it, waste all that money and have nothing?

          If I'm building a house and it's over budget, I do what I can to get it finished. At least then I have a house to live in.

          Was the Constellation project really broke?

          How much money do you flush down the toilet instead of seeing it through and having a product?

    • In span of time between missions, there is usually incredible progress in a few key parameters, detector noise, spacial resolution, and frequency range. While you can argue that a "refueled" IRAS could beat down the noise by observing for years and years, changing out detectors and telescopes is effectively launching a new mission. Also, as our knowledge of astrophysics grows, we design missions to answer the unanswered questions. 10 years of IRAS is not necessarily as interesting as a couple of years of

  • I understand if it can produce good science in a new orbit, but if it's being moved primarily to avoid cluttering up L2, I think that might be a mistake. Presumably it isn't moving very fast relative to L2, so another craft in L2 orbit should be able to capture it fairly easily. Sooner or later we'll have some kind of station at L2, and Herschel's parts will likely be useful somehow. Will it have sufficient power and good thrusters in 30 years if it's mothballed in place now? Why not wait and move it later
    • Re:leave it at L2 (Score:4, Informative)

      by NixieBunny ( 859050 ) on Wednesday March 06, 2013 @11:57AM (#43093169) Homepage
      Hopefully, the scientific instruments will have improved substantially in 30 years, so its guts will be obsolete and therefore useless. As a worker in terrestrial radio astronomy, I can assure you that we don't use any receivers more than 15 years old, and those are about 5x less sensitive than current instruments. Any system designed for space will use the latest proven technology, given the cost to get it up there.
    • by AlecC ( 512609 )

      The whole point of moving it is that without liquid helium it cannot effectively do any science at all.

      I really do not think it is ever likely to be possible to reuse parts of a satellite not designed to be reused.

      I think it is a long time before we will want a station at L2. L4 and L5 are more useful for things other than exactly what this satellite was sent to do. The only thing we are likely to send is the James Webb telescope, effectively its successor, in a few years time, and we don't want any chance

    • It would cost you more to build something to catch it at L2 and refill the dewar than to just build a new one-- it wasn't designed to have any sort of docking and refill capability. It will eventually fall out of L2 into a heliocentric orbit anyway, so they're probably just going to do it in a controlled way.

    • Re:leave it at L2 (Score:5, Informative)

      by Trapezium Artist ( 919330 ) on Wednesday March 06, 2013 @01:38PM (#43094769)

      It's not being moved because it will clutter up L2. Indeed, such satellites don't sit exactly at the L2 point, but travel around it in orbits which are hundreds of thousands of kilometres wide. There's effectively no danger of any satellites at L2 hitting future ones.

      No, the reason is that L2 isn't a stable location: the gravitational potential there is saddle-shaped. Very crudely, along the line of the orbit around the Sun, the satellite sits at the bottom of a curve. Move forward a bit and the Earth's gravity pulls you back. Fall behind a little bit and the same happens. However, perpendicular to the orbital track, in the plane of the ecliptic (the plane containing the planets), it's more like the top of a gravitational hill. Fall a little away from the Earth and bingo, the Earth is no longer strong enough to pull you back and you fall off, outwards.

      But if you fall inwards, towards the Earth, the Earth's gravity gets stronger and pulls you even closer. So much so, that you might end up hitting the Earth.

      So that's the reason why Herschel and other satellites there (WMAP in the past, Planck today, Gaia and JWST in the future) are pushed off L2 while the satellites still have propellant and are functional (if not scientifically) into heliocentric orbits, to prevent the possibility of the falling onto the Earth in an uncontrolled manner later.

      • Thanks, I'd forgotten that objects at L2 don't stay there forever. Which is good, if you don't want rocks eventually hitting your telescopes. Others misunderstood the point of saving it—not to reuse it (except possibly the mirror(s) ), but to reuse the materials in it, as expensive as it is to put mass into orbit. We've got to look forward more than a few dozen years. I also took exception to the notion that L2 isn't much good for anything in the future besides JWST.

        By the same logic, instruments we s

A sine curve goes off to infinity, or at least the end of the blackboard. -- Prof. Steiner