Slashdot Mirror

← Back to Stories (view on slashdot.org)

Successful Launch of ESA's Herschel and Planck

Posted by CmdrTaco on from the round-and-round-they-go dept.

rgarbacz writes "Today at 13:12 GMT, the ESA launched successfully new and long-awaiting spacecraft: Herschel, the infrared telescope with a 3.5m mirror, and Planck, the CMB mapper. The spacecraft were carried by the Ariane-5, which lifted off from Kourou in French Guiana. They will stay in L2 to perform the research. This launch is one of the most expensive and important missions of the European Space Agency. Planck will measure the CMB with an accuracy more than 10 times better than the previous mission, WMAP. Because of this high sensitivity, both spacecraft are cooled to temperatures close to absolute zero by on-board liquid helium; staying in L2 is very helpful to maintain this state. Both spacecraft are designed to observe the Universe at its infancy: Herschel by observing the first stars and galaxies (whichever came first), and Planck by scrutinizing the first photons that were set free, making up the cosmic microwave background radiation."

39 of 121 comments (clear)

  1. with accuracy below 1% by tsalmark · · Score: 5, Funny

    even if it is ten times more accurate than before, I think we have a long way to go.

  2. SuperAccurate by wild_quinine · · Score: 4, Insightful

    Planck will measure CMB with accuracy below 1%

    Uhm. Is this technical terminology that I simply don't understand, or just a typo? Because I can understand a '1% margin of error', and I can sort of understand 'accurate to 1%'... but something which is below 1% accurate?

    If only I could get away with that in my job.

    1. Re:SuperAccurate by Anonymous Coward · · Score: 4, Informative

      The correct term would be inaccuracy. Calling it accuracy is misleading, but very common.

    2. Re:SuperAccurate by sofar · · Score: 3, Insightful

      Most likely due to:

      - funding (the launch phase costs the most because everything has to be tested & proven before it even goes up).
      - other projects going up first (short-term projects slip in first etc), occupying launch events.
      - feasibility (sometimes a great idea just is too risky)

      in that order. it's not rocket science :)

    3. Re:SuperAccurate by TorKlingberg · · Score: 2, Interesting

      Probably waiting for Herschel to be finished so they could launched together.

  3. What? by Anonymous Coward · · Score: 2, Funny

    Accuracy below 1%? Did someone put a not gate in the wrong place?

  4. Another Job well Done by Leafheart · · Score: 2, Interesting

    Between this and the fix ongoing on Hubble, where are set for some more time of great and impressive astronomy. Thank you NASA and ESA for keeping the good work.

    Any one have any idea how they will keep the helium going on it? I tried on the articles but couldn't find the longevity and repair plans.

    --
    --- "When you gotta do something wrong. You gotta do it right. (Fighter)"
    1. Re:Another Job well Done by whathappenedtomonday · · Score: 5, Informative

      Herschel is supposed to complete its mission in three years, Planck in only 15 months. After the helium supplies have evaporated, their missions end. They won't be repaired / serviced, because they are too far away to be easily reached with a shuttle. That's what local news here say.

      --
      I hope I didn't brain my damage.
    2. Re:Another Job well Done by smooth+wombat · · Score: 2, Interesting

      After the helium supplies have evaporated,

      I realize we, as in all space agencies, use helium or something else to keep these instruments cold, but why can't we use the coldness of space to do the same thing? Isn't there some way to use one or more of the three forms of heat transfer to keep the instruments cold enough to work without having to rely on a limited source of helium?

      --
      We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
    3. Re:Another Job well Done by imsabbel · · Score: 5, Informative

      Well, that's because the space is too hot.

      Even without the sun.

      They are trying to measure the CMB. If you are not colder than outer space, most of the radiation would just come from the telescope itself...

      --
      HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
    4. Re:Another Job well Done by whathappenedtomonday · · Score: 5, Informative

      "In order to study the coolest places in the Universe the Herschel instruments must be cooled to just above absolute zero. A large cryostat surrounds the instruments maintaining an operational temperature of 1.7 K for a nominal mission lifetime of 4 years." ESA has some great info on their site.

      --
      I hope I didn't brain my damage.
    5. Re:Another Job well Done by m50d · · Score: 4, Informative
      I realize we, as in all space agencies, use helium or something else to keep these instruments cold, but why can't we use the coldness of space to do the same thing?

      Because what they're trying to measure is, in some senses, the temperature of space itself - the ~3K CMB. So they need the detector to be colder than that.

      Isn't there some way to use one or more of the three forms of heat transfer to keep the instruments cold enough to work without having to rely on a limited source of helium?

      No. The radiative coolers (can't really use conduction or convection in space) will keep the craft cold enough for the low frequency instrument to work, even after the helium* runs out, but to get the 0.1K that the high frequency instrument needs, there's no (good) alternative to this active cooler.

      * Well, not after the helium in its own refrigerators runs out. But it's not actively venting that, so we only have leakage to worry about there.

      --
      I am trolling
    6. Re:Another Job well Done by FireFury03 · · Score: 3, Informative

      I realize we, as in all space agencies, use helium or something else to keep these instruments cold, but why can't we use the coldness of space to do the same thing?

      Space isn't really "cold", or rather, the terms "cold" and "hot" lose much of their meaning when you're talking about incredibly low densities like you have in space.

      If you have an atmosphere then you transfer heat by radiation and conduction. You can cool your instruments by putting them in the shade (so they don't get the radiated energy from the sun) and ensuring the atmosphere is cool so that it will conduct the heat away. The atmosphere on Earth is actually not a great conductor, but because it is a fluid you can keep the air moving so that as soon as some of the heat has been conducted to the surrounding air you move that (warmer) aid out of the way and replace it with cool air - this can be done naturally by convection or by forcing the air to move with a fan.

      In space you have practically no atmosphere, so the heat transfer is almost entirely by radiation - your instruments are essentially in a giant vacuum flask. Your satellite needs to reflect away the energy radiated by the sun, and the cosmic microwave background radiation, etc. and also radiate away its own heat (remember, these satellites contain lots of electronics and like all electronics they will generate heat). This is a pretty tall order - surfaces that radiate well are also really good at absorbing energy. - I imagine it's much cheaper and lighter to send up a load of liquid helium and dissipate the heat by letting it boil away.

      --
      http://blog.nexusuk.org
    7. Re:Another Job well Done by mmontour · · Score: 2, Informative

      I realize we, as in all space agencies, use helium or something else to keep these instruments cold, but why can't we use the coldness of space to do the same thing?

      According to this PDF the Planck mission does not use liquid helium coolant (although Herschel does). Also the upcoming James Webb telescope will not use it.

    8. Re:Another Job well Done by borizz · · Score: 3, Informative

      Space radiates. If we were to put a black body in space at absolute zero, after a while it would be about 2.7 Kelvin. This is because of the cosmic microwave background (which is what they're trying to measure here).

      If you have a distractor (radiation from the craft itself) as big as the thing you're trying to measure, you won't get good results.

    9. Re:Another Job well Done by Patch86 · · Score: 4, Insightful

      To put it another way- heat is full of microwaves (the same as are in your kitchen appliance) which heats up everything in space to a certain point (2.7 Kelvin, if it's a black something). If you simply rely on "the coldness of space" to cool you down, that's as cool as you're going to get.

      That's still EXTREMELY cold, but for this particular mission it's not cold enough. This mission is to measure said background radiation, meaning that in order to do it's job it must be colder than that extremely low temperature that is "the coldness of space".

    10. Re:Another Job well Done by forand · · Score: 4, Insightful

      There is a huge technical problem that many of the above posters have ignored. To use "space" as a heat sink requires you to conduct that head to space. However, space is very close to vacuum and thus it is near impossible to conduct heat away. The other option is to radiate heat away this requires that you have something which is very efficient at radiating in the peak frequency for the nominal temperature of the radiator. To make a long story short you cannot use radiative cooling to cool something to near zero in space because you are being bathed by 2.7k blackbody radiation.

    11. Re:Another Job well Done by jandersen · · Score: 2, Interesting

      Well, you can with a fridge, which basically pumps the heat out of a confined space and heats the radiator grille on tha back, and you could in principle do the same for a satelite - in fact, I am pretty sure they do something similar to that in order to make the helium last for that long. But helium is pretty difficult to hold on to, it tends to leak out through any pressure seals, because it is comes as single atoms which are much smaller than even the two-atom molecules of hydrogen. And of course a cooling compressor, being a mechanical device, has parts that wear out and seals that get leakier over time.

  5. L2? by bradgoodman · · Score: 2, Informative

    What is "L2"?

    1. Re:L2? by Morphine007 · · Score: 4, Informative

      Wiki Entry for Lagrange Point

      --
      Oh god, that woman is John Romero!
    2. Re:L2? by Ornedan · · Score: 4, Informative

      Lagrange point. Location where the gravitic pulls of some objects cancel each other out. In this case, it's Earth and Moon.

    3. Re:L2? by Anonymous Coward · · Score: 3, Informative

      Lagrange point 2, one of the 5 locations in space around an orbiting body where the gravity wells from the major surrounding bodies cancel each other out, providing a sort of "still point" in space.

      http://en.wikipedia.org/wiki/Lagrange_point

      Ah how, how, how, how....

    4. Re:L2? by Morphine007 · · Score: 2, Informative

      Sorry, GP ... I just realized that posting the wiki link like that was basically akin to saying "L2wikipedia, noob", but it wasn't intended that way: The article doesn't actually say that the "L2" where the spacecraft are "staying" is actually the L2 Lagrange Point. Basically, as the wiki mentions and as others have stated, it's one of the 5 well known points where gravitational forces between the sun, moon and earth all cancel each other out. So the satellites can basically "hover" in the exact same position (relative to the earth and the sun) without having to move. For these particular satellites, that allows them to always stay in the earth's shadow, and, when their positioning (relative to the sun) allows for them to study a particular area in space, they won't have the earth periodically passing between them and whatever they're studying.

      --
      Oh god, that woman is John Romero!
    5. Re:L2? by MozeeToby · · Score: 2, Insightful

      Also, at the L2 point, all three major heat sources (Sun, Earth, and Moon) are in the same direction. This allows them to have a single heat shield to block radiation from those sources, reducing the cooling needs. When you're trying to keep something at 1.5K, even the light shining off the moon can make a pretty big difference in how much it takes to maintain that temperature.

    6. Re:L2? by Cowmonaut · · Score: 2, Funny

      +1 ZZ Top

    7. Re:L2? by hcg50a · · Score: 3, Informative

      Actually, it's the Earth and the Sun. It's on the Earth-Sun line, behind the earth (from the sun's point of view), and orbits the sun once a year. They put it here because it's easier to shield the satellite from both the Sun and Earth.

      The L2 point for the Earth-Moon system is on the Earth-Moon line, behind the moon, and orbits the earth once evry 29.5 days.

      --
      HCG 50a = 2MASX J11170638+5455016
      11h17m06.4s +54d55m02s
  6. Blame rgarbacz by mangu · · Score: 5, Informative

    It seems like the summary writer didn't understand TFA. Quoting from ESA:

    Planck is designed to 'see' the microwaves and, in practice, it will detect them by measuring temperature. That temperature is already known to be about 2.7K (which is very cold, about 270C, near absolute zero). It has been measured to be 2.726K all over the sky to three decimal figures. This degree of accuracy in the measurement may seem good enough, but much more precise measurements are needed.

    The older measurements that Planck is trying to improve already are accurate to 0.1%.

    It seems like someone got confused with the coincidence that the temperature of the universe, 2.7 K, is about 1% of the temperature of freezing water, 270 K.

    1. Re:Blame rgarbacz by pwfffff · · Score: 3, Interesting

      "(which is very cold, about 270C, near absolute zero)"

      I think you dropped this: -

  7. Re:FFS by johannesg · · Score: 2, Informative

    "new and long awaiting spacecrafts....both spacecrafts are cooled...Both spacecrafts are designed"

    Plural of "spacecraft" is "spacecraft".

    English, do you speak it?

    Actually Herschel and Planck are _two_ of the most expensive and important missions. But maybe we are being too hard on the author of this piece, who may not have english as his native language.

    Indeed, the working language of ESA is something known as "franglais". It sounds like french and has grammar like french, but uses mostly english words. From experience, a communication like the article summary is actually pretty good by ESA standards...

  8. Far out and still close to home... by yogibaer · · Score: 3, Interesting

    First emotion: Wow! Far out: L2 is 1.5 million km from Earth beyond the orbit of the moon ( so no space shuttle service missions here... ). But before I looked it up I had completely forgotten that Mars is at best still another 53 million km and then imagining the billions of lightyears Herschel will be able to "see"... I have to buy another ticket for "Star Trek" to lose this image of an invisibly tiny blue spec in a black void in my head...

  9. Happy launching by KasperMeerts · · Score: 3, Interesting

    It's really awesome this thing launched succesfully. My professor of astronomy and his department worked ten years on Herschel. I'm really happy for him.

    I hope the sattelite gives us a lot of useful information or at least some beautiful pictures

    --
    As long as there are slaughterhouses, there will be battlefields.
    1. Re:Happy launching by Canazza · · Score: 4, Funny

      it's all about the pretty sparkle isnt it?

      If I don't get new desktops by June I will NOT be happy...

      --
      It pays to be obvious, especially if you have a reputation for being subtle.
  10. Re:FFS by rgarbacz · · Score: 2, Interesting

    I am grateful for the correction, and I am sorry for the mistake. English is not my native language. And please do not contribute this error to ESA - I do not work for this agency, I am just a space exploration enthusiast.

  11. Re:FFS by richmaine · · Score: 4, Funny

    Plural of "spacecraft" is "spacecraft".

    But the plural should be spacecreft!

    Spacecruft?

  12. Free Software On Both by joelsherrill · · Score: 5, Interesting

    As maintainer of RTEMS, I am very proud that both spacecraft are running our free real-time operating system on at least the Spacecraft Management Unit (SMU). These are both important missions which promise to provide us with new insights.

    1. Re:Free Software On Both by powerlord · · Score: 3, Funny

      Nice site. Interesting project.

      Its a good thing they didn't put (insert x86 architecture OS here) on them.

      I can see the first message sent back containing the words "No keyboard present. Press F1 to continue." ... followed by a prolonged silence. ;)

      --
      This space for rent. All reasonable inquiries will be entertained at proprietors discretion.
  13. Re:FFS by 1u3hr · · Score: 2, Insightful
    But maybe we are being too hard on the author of this piece, who may not have english as his native language.

    I don't blame the original author, but the incompetent editors who should have noticed and fixed it before publishing it.

  14. Herschel and Planck? by cwiegmann24 · · Score: 2, Interesting

    I understand that they're named after some famous scientists, but how are these names any better or more notable than Colbert? It's not like I'm going to remember Sir William Herschel and Max Planck any better because they have a spacecraft named after them. I had to look both up cause I didn't know who they were.

  15. Which L2? by camperdave · · Score: 2, Interesting

    Which L2? There are several. The convention is to express it with the initial of the Large body, then the initial of the small body: eg the Sun-Earth L2 would be SEL2; the Earth Moon would be EML2. I'm guessing this would be SEL2 so that the Earth blocks out a lot of the radiation from the Sun. Anyone know if SEL2 is within the umbra of the Earth's shadow?

    --
    When our name is on the back of your car, we're behind you all the way!