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Last Post 5/20/2015 11:12 AM by  Kris Sigsbee
Solar Energy
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5/20/2015 6:34 AM

    Chris W

    What's the farthest we've used solar power on spacecraft in space? thanks

    Tags: Jupiter, Juno, Solar Panels, solar power, New Horizons, Voyager, RTG

    Christina Cohen

    Basic Member

    Basic Member

    5/20/2015 11:05 AM

    Hi Chris,

    Once the Juno spacecraft reaches Jupiter in mid-2016 it will be the farthest spacecraft to use solar panels. Since the solar power drops very quickly with distance from the Sun, it is hard to get enough power from solar panels beyond around Jupiter's orbit.

    Juno has the largest solar panels a deep-space NASA probe has ever had; they are each about 9 by 30 feet and there are 3 of them. Near Earth together they would provide about 13000 watts of power but at Jupiter they will only produce about 480 watts.


    Kris Sigsbee

    Basic Member

    Basic Member

    5/20/2015 11:12 AM

    Hi Chris,

    Until recently, the spacecraft sent to explore the outer planets (Jupiter, Saturn, Neptune, Uranus, Pluto) have relied upon radioisotope thermoelectric generators, or RTGs to provide power. An RTG is not a nuclear reactor, but it does use highly radioactive materials to produce power. The New Horizons mission to Pluto is powered by an RTG. The Voyager missions also used RTGs, as did other recent planetary science missions such as Cassini. You can read more about RTGs and how they work here:

    The Juno mission, which is currently on its way to explore Jupiter, is the very first mission to the outer planets to use solar panels to power the spacecraft. This was accomplished by advances in solar cell technology and by making the solar panels very large. You can read more about the Juno mission here:


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