NASA’s Juno spacecraft was launched in 2011. It lifted off on August 5, 2011, from Cape Canaveral Air Force Station in Florida aboard an Atlas V 551 rocket, beginning a nearly five-year journey to Jupiter.
Juno was designed to investigate how Jupiter formed and evolved. Its instruments measure the planet’s gravity and magnetic fields, probe the atmosphere’s water and ammonia, study the auroras, and examine the structure hidden beneath the cloud tops. Because Jupiter preserves material from the early Solar System, those measurements also help scientists test ideas about planetary formation.
The route was deliberately indirect. After deep-space maneuvers in 2012, Juno returned toward Earth for a gravity-assist flyby in October 2013. Earth’s motion gave the spacecraft extra energy, allowing it to reach Jupiter without a much larger launch vehicle. Juno entered Jupiter orbit on July 4, 2016.
The year 2011 is sometimes confused with 2016, but 2016 was the arrival and orbital-insertion year, not the launch year. Juno is unrelated to ESA’s later JUICE mission.