After a journey of nearly five years and 2.8 billion kilometres, the Juno spacecraft arrived at Jupiter on July 4, 2016, to begin a 20-month examination of the solar system’s largest planet. Juno is only the second probe to orbit Jupiter — the first was Galileo, which arrived in 1995. All other missions were simply brief (but productive) “flyby” encounters.
After initial manoeuvres, Juno will begin to circle Jupiter in a highly elliptical orbit that brings it to within 5,000 kilometres of the planet every 14 days, starting in October. The spacecraft will have its close approach (perijove) over Jupiter’s polar regions to avoid the most intense areas of the big planet’s dangerous radiation belts. Each time it does so, Juno will image atmospheric belts, zones and spots in spectacular detail. But that’s not all.
The primary mission objective is to shed light on Jupiter’s origin. Juno will do this by examining the planet inside and out. A suite of nine scientific instruments is set to probe Jupiter’s incredibly deep and complex atmosphere, the swirling sea of liquid metallic hydrogen beneath it, and the solid core (assuming one exists) that may have “seeded” the planet’s formation. To complete the picture, the spacecraft will record subtle variations in the gas giant’s powerful gravitational field and map its enormous magnetosphere.
This video includes computer animation and Juno’s first images of Jupiter and its moons.