Just before Juno enters Jupiter’s orbit in 2016, the spacecraft, pulled by the gas giant’s tremendous gravity, will reach speeds of 134,000 miles an hour, making it one of the fastest human-made objects ever built. Once in orbit, the craft will make 33 passes around the planet and then dive directly into it. On its suicide run, it will plow through Jupiter’s hydrogen atmosphere until it burns up like a meteor.
While Juno circles Jupiter, a suite of nine instruments will study the planet’s many layers. Jupiter was the first planet in the solar system to form, and because it is so large, its gravity has retained original material found in the early solar system, primarily hydrogen and helium. This characteristic makes the planet a valuable window into the solar system’s origins. Measurements of Jupiter’s magnetic field could finally resolve the debate over whether the planet has a rocky core. Juno’s magnetometers will characterize the depth and motions of the metallic hydrogen ocean found in the interior, which generates the strongest magnetic field in our solar system aside from that found around the sun. Finally, a microwave radiometer will measure the amount of water in Jupiter’s deep atmosphere, a key to understanding how the planet was originally formed.