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NASA Space Science

NASA To Cryogenically Freeze Satellite Mirrors 47

Posted by Soulskill
from the ain't-it-cool dept.
coondoggie writes "NASA said it will soon move some of the larger (46 lb) mirror segments of its future James Webb Space Telescope into a cryogenic test facility that will freeze the mirrors to -414 degrees Fahrenheit (~25 K). Specifically, NASA will freeze six of the 18 Webb telescope mirror segments at the X-ray and Cryogenic Facility, or XRCF, at NASA's Marshall Space Flight Center in Huntsville, Alabama, in a test to ensure the critical mirrors can withstand the extreme space environments. All 18 segments will eventually be tested at the site. The test chamber takes approximately five days to cool a mirror segment to cryogenic temperatures."
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NASA To Cryogenically Freeze Satellite Mirrors

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  • Talk about getting a cold look....
  • by Anonymous Coward on Friday January 08, 2010 @09:21PM (#30703656)

    that they don't get their imperial units mixed up with metric units, and freeze the thing to -414C instead.

    • that they don't get their imperial units mixed up with metric units, and freeze the thing to -414C instead.

      Thinking about those lasers which are used to cool small particles to near zero temperatures. Can the photons from those lasers be considered to have a negative temperature, because of the energy they remove from the particles being cooled?

      • Can the photons from those lasers be considered to have a negative temperature, because of the energy they remove from the particles being cooled?
        Maybe [wikipedia.org].

      • Hmmm interesting concept... I guess it could but don't take my word for it i've only read about them in a newspaper article I while doing papier machie...
      • by MstrFool (127346)

        I wouldn't think so. At least not any more then a speaker can be considered to create negative sound when it is used for phase cancellation in noise canceling headphones. Or that one truck can be said to have a negative velocity when it impacts an other truck heading in the other direction and they both stop dead. But then this is just my personal opinion YMMV.

      • by div_B (781086)

        Thinking about those lasers which are used to cool small particles to near zero temperatures. Can the photons from those lasers be considered to have a negative temperature, because of the energy they remove from the particles being cooled?

        Not really... negative temperature can be a 'meaningful' concept in some scenarios, but it's not necessary to invoke it here. Temperature is a property of an object such that two objects in contact (or exchanging radiation, etc) with different temperatures will exchange energy (heat) so as to try and 'meet each other in the middle', i.e., hot one loses energy to the colder one until the the temperatures become equal. Basically the character of laser beams is that they are not-very-thermal-at-all, so you c

    • by Kjella (173770)

      I'd say the Nobel prizes in physics they'd get from it would more than make up for their little "accident". The odds are about as good as accidentally making FTL travel though.

  • http://www.youtube.com/watch?v=VNaDZIrxh-0 [youtube.com]
    At least nobody can complain they aren't doing some thorough testing on this project.

  • by hyades1 (1149581) <hyades1@hotmail.com> on Saturday January 09, 2010 @09:01AM (#30706962)

    "The test chamber takes approximately five days to cool a mirror segment to cryogenic temperatures."

    My ex could do it in about one and a half seconds with a single glare. Of course, then she'd have to bask on a rock for a couple of hours to recover.

  • As this summary has been tagged with 'science' I'd expect scientific terms to be used.

    Are these mirrors actually liquid at room temperature, or perhaps the submitter meant 'cool' rather than 'freeze'?

  • Getting it right (Score:3, Informative)

    by skoda (211470) on Saturday January 09, 2010 @01:10PM (#30708450) Homepage

    Unfortunately the article gets the technical aspects wrong.

    NASA is not "freezing" the mirror segments to make sure they "survive" space.

    The JWST will operate at a cryogenic temperature in space. The mirrors are measured at cryovac to guide the manufacturing process so they will have the correct optical prescription at the telescope's operational temperature.

    Similarly, we're testing support optics, for the pre-launch JWST testing, at cryo. We'll have the first of a one set down to temp in short order.

  • It'll be interesting to thaw these mirrors 50 or 100 years into the future and see what they have to say about the past. Maybe then we'll have the technology to their cracks and heal them. Wait, what we were talking about again?

"Out of register space (ugh)" -- vi

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