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NASA Hardware Hacking Space

Solar Pressure May Help Kepler Return To Planet-Hunting Duties 46

Posted by samzenpus
from the back-to-the-search dept.
Zothecula writes "Last August, it looked as if NASA's Kepler space telescope was as good as scrap due to the failure of its attitude control system. Now the space agency proposes what it calls the K2 mission concept, which may fix the problem by using the Sun to regain attitude control and allow Kepler to resume its search for extrasolar planets."
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Solar Pressure May Help Kepler Return To Planet-Hunting Duties

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  • I did not know that telescopes had an attitude to begin with. How does adjusting attitude allow a telescope to search for planets?
  • Attitude Control (Score:4, Informative)

    by Thanshin (1188877) on Monday December 02, 2013 @01:55PM (#45576007)

    Attitude control [wikipedia.org]

  • by Anonymous Coward

    "Whether or not K2 goes ahead depends on the results of NASA's 2014 Senior Review and the acceptance of a budget for the mission."

    One would think the cost of keeping it going would be absolutely minimal, manufactured and launched as it is... did they cut funding when the 2nd wheel failed?

    • Re: (Score:2, Offtopic)

      by Lumpy (12016)

      Actually they did. Ceasar cut all funding on wheels and called them a failure. Luckily private chariot companies picked up where they left off and created the booming chariot industry that carried Rome from it's beginning, to burning and beyond.

  • by bob_super (3391281) on Monday December 02, 2013 @02:09PM (#45576097)

    Solar pressure? The only thing that works for attitude control is peer pressure (for lack of a timeout corner in orbit).

    Tell Grandpa Hubble to shame Kepler into behaving.

  • by Anonymous Coward

    Wow, these guys are smart. What are they, rocket scientists or something?

  • by lazarus (2879) on Monday December 02, 2013 @02:12PM (#45576135) Journal

    This is fascinating, but what I find even more interesting is why they couldn't use a similar technique to make the need for the attitude control wheels obsolete? It would require a spacecraft much different than Kepler, but would it not be possible to use sails to orient a similar craft no matter what area of the sky it wanted to point to?

    • by beschra (1424727)

      Maybe they will next time.

    • Re:Light Sail (Score:4, Insightful)

      by JoeMerchant (803320) on Monday December 02, 2013 @02:23PM (#45576213) Homepage

      Variability and unpredictability of the solar wind?

      It could work, but it would be like reverting from steamships to sail power, and in the billion dollar satellite business, answering the question "when will our gizmo be working?" with something like "well, between 10 and 40 days, depending on what kind of winds we get..." might not be as satisfying for the businessmen as "27 days, 13 hours and 6 minutes, +/- 30 seconds, depending on interference from the solar wind."

      • Re: (Score:2, Interesting)

        by Anonymous Coward

        Solar wind isn't what solar sails use, despite the name. A solar sail works by photon pressure, and the Sun is pretty stable when it comes to that.

        • Re: (Score:2, Funny)

          by MightyYar (622222)

          the Sun is pretty stable when it comes to that

          Then how do you explain global warming?

          (I keed, I keed...)

    • Re:Light Sail (Score:5, Informative)

      by 0123456 (636235) on Monday December 02, 2013 @02:46PM (#45576445)

      This is fascinating, but what I find even more interesting is why they couldn't use a similar technique to make the need for the attitude control wheels obsolete?

      Wouldn't work very well near Earth, because you're in darkness much of the time and there's enough atmosphere left that drag might be larger than any force you could create from light pressure.

      But I seem to remember that Mariner Mercury used light pressure on its solar sails for attitude control when it could, to miminize fuel use by the thrusters.

      • Re:Light Sail (Score:5, Informative)

        by Deadstick (535032) on Monday December 02, 2013 @03:13PM (#45576773)

        Mod parent up. In Earth orbit, aerodynamic wind is very tiny but so is solar wind, and solar steering as a primary attitude-control system would be very complex. Acceptable as a last-ditch fallback, but you wouldn't want to base a mission on it.

    • by Herve5 (879674)

      This works, but provides verrry small torques or forces.
      FWIW, a couple of years ago, with my (european space industry) employer and a neighbor astronomy lab we designed a device involving a large and rough telescope concentrating light on mobile smaller mirrors, so as to provide torques or even forces, but very low, to light and very slowly moving spacecrafts. We wanted to deploy a flock of these, coordinating them to form a very large, multipart space telescope. Then, well, money went on missing. This will

    • This is fascinating, but what I find even more interesting is why they couldn't use a similar technique to make the need for the attitude control wheels obsolete? It would require a spacecraft much different than Kepler, but would it not be possible to use sails to orient a similar craft no matter what area of the sky it wanted to point to?

      The advantages are obvious, but there are disadvantages:

      1. It doesn't work near the Earth, because atmospheric drag, magnetic torque, and gravity gradient torque are all considerably larger than radiation pressure.

      2. The forces are tiny, so your spacecraft won't be very agile. If you need to reorient to change targets or point an antenna at Earth to send your downlink, it'll take awhile.

      3. While as an exercise in applied physics radiation pressure may be the simplest attitude control method, it doesn

  • by BenSchuarmer (922752) on Monday December 02, 2013 @02:13PM (#45576139)
    Don't make me get my asteroid belt!
  • by Jeremy Erwin (2054) on Monday December 02, 2013 @02:18PM (#45576183) Journal

    The whole point of scrapping a ship is that the steel can be reused for other purposes. The Kepler space telescope can't be scrapped-- it's in the wrong sort of orbit to be returned to earth. From that perspective, it's actually worse than scrap.

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