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The reason we plan to crash Juno into Jupiter at the end of the mission
is for what's called planetary protection.

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We can't make the spacecraft perfectly sterile. 

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We try to keep it as clean as possible
and we spend quite a bit of effort dressing up in bunny suits

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and putting it in a clean room that's changing air as fast as we can do it
and trying to keep it as clean as possible

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but nothing's perfectly clean.

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The United States is part of an international treaty

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that says we will be sure not to contaminate
other worlds that could potentially harbor life.

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There are some moons around Jupiter and Mars
and other places that kind of look a little enough like Earth

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that we're thinking well maybe there is
a life that we would recognize there.

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You would really hate to, fifty years from now
send a mission to, say, Europa, one of the moons of Jupiter

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and find life and then not be able to tell whether
this is Europan life or contamination from Juno.

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So what we do is we dispose of JUNO when we're done with it
and we let it burn up in Jupiter's atmosphere.

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There's about a 99 percent chance that what would eventually happen to it
is it would crash into Jupiter, burn up, not contaminate anything.

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But 99 percent chance isn't good enough for us. It isn't good enough for NASA.

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We need to show by agreement with NASA that we have
a less than one chance in ten thousand of contaminating Europa.

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So while we still have control
before the radiation has done any damage

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we'll fire the rockets, we'll burn Juno up
in the upper atmosphere of Jupiter 

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and that way we'll be certain we're not
going to contaminate anything.