After more than a year orbiting Jupiter, Juno's science mission will be complete. The Juno spacecraft will then be commanded to dive into Jupiter's atmosphere where it will burn up like a meteor. Juno will become part of the planet it has studied.
After 33 orbits passing through Jupiter's radiation belts, the spacecraft will have received a large dose of radiation, and more radiation would eventually cause its systems to fail. So the spacecraft is de-orbited to meet the planetary protection requirement set by NASA.