"Have fun riding though the atmosphere ... and have a very safe and exceptionally soft landing."
SpaceX has more than 70 missions on its manifest, worth more than $10 billion, for commercial and government customers.
It is located about 4.2 light-years from Earth, or 25 trillion miles (40 trillion km)
If anything went even slightly awry, Juno would have sailed helplessly past Jupiter, unable to complete a $1 billion mission.
Water figures are the most important ones that Juno is going to bring back.
"Nine of these orbit in their sun's habitable zone."
NASA said that after retiring, Kelly, 52, will still work on ongoing research related to his time in space.