The reason we plan to crash Juno into Jupiter at the end of the mission is for what's called planetary protection.
We can't make the spacecraft perfectly sterile.
We try to keep it as clean as possible and we spend quite a bit of effort dressing up in bunny suits
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
but nothing's perfectly clean.
The United States is part of an international treaty
that says we will be sure not to contaminate other worlds that could potentially harbor life.
There are some moons around Jupiter and Mars and other places that kind of look a little enough like Earth
that we're thinking well maybe there is a life that we would recognize there.
You would really hate to, fifty years from now send a mission to, say, Europa, one of the moons of Jupiter
and find life and then not be able to tell whether this is Europan life or contamination from Juno.
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.
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.
But 99 percent chance isn't good enough for us. It isn't good enough for NASA.
We need to show by agreement with NASA that we have a less than one chance in ten thousand of contaminating Europa.
So while we still have control before the radiation has done any damage
we'll fire the rockets, we'll burn Juno up in the upper atmosphere of Jupiter
and that way we'll be certain we're not going to contaminate anything.