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Voyager probe RTG energy saving

Discussion in 'Electronic Basics' started by Bob Masta, Nov 30, 2011.

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  1. Bob Masta

    Bob Masta Guest

    There have been stories in the news lately about NASA
    switching the Voyager 1 and 2 probes to using backup
    thrusters to save energy. This is supposed to save 12 watts
    by allowing the primary thruster heaters to be turned off.

    <www.space.com/13538-nasa-voyager-spacecraft-backup-thrusters.html>
    <www.time.com/time/health/article/0,8599,2099245.00.html>

    The articles claim that this energy saving will allow
    extended lifetime of the power supply, which is a
    radioisotope thermoelectric generator powererd by decay of
    plutonium 238.

    Huh? How does the electrical load on the thermocouples have
    any effect on the decay of plutonium?

    No explanation is offered. Assuming the life extension is
    correct, my only guess is that it is some strange
    second-order effect, like maybe the thermocouples have some
    sort of electromigration failure mode that is sped up at
    higher currents... or something.

    Anyone know the true story?

    Best regards,


    Bob Masta

    DAQARTA v6.02
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  2. BeeJ

    BeeJ Guest

    fungus explained on 11/30/2011 :
    You have to squeeze plutonium really hard to get juice and then it
    doesn't taste all that good.
     
  3. Chiron

    Chiron Guest

    On Wed, 30 Nov 2011 13:23:05 +0000, Bob Masta wrote:


    I'm not sure how the reactor in space is managed; on earth, the rate of
    fission is controlled through the use of moderators that can cause it to
    speed up or slow down. If they can save some energy, that means they can
    reduce the rate of fission, extending the life of the fuel. But as I
    said, I don't know whether they use controllable fission or whether the
    rate is fixed.
     
  4. Guest

    Correct. It's not a "reactor" at all in that there is no "chain reaction" to
    control/moderate. It's simple radioactive decay of a lump of PU. As the PU
    decays it generates less heat, less delta-T = less power generated. The
    "power management" that's going on is simply choosing which instruments to
    shut down so the thing operates the most interesting experiments (and of
    course the radios) with the available power left.
     
  5. bw

    bw Guest

    PU must mean some chemical combination of P and U
    Plutonium is Pu
    Phosphorus is P
    Uranium is U
     
  6. Guest

    What a moron.
     
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