Juno at Jupiter
Juno's three solar-panels provide both energy and stability for the slowly turning spacecraft. (NASA/JPL)
Juno at Jupiter: Arrival

For the first time in thirteen years, a spacecraft is orbiting the biggest planet.

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.

Juno at Jupiter
This illustration depicts NASA’s Juno spacecraft in orbit around Jupiter, the solar systems laragest planet. Juno’s three solar panels provide both energy and stability for the slowly turning spacecraft. (NASA/JPL)

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.

Juno Jupiter image #1
This first orbital view of Jupiter and three of its satellites was captured on July 10, 2016, at 10:30 a.m. PDT (1:30 p.m. EDT), when the spacecraft was 4.3 million kilometres (2.7 million miles) from the planet on the outbound leg of its initial 53.5-day capture orbit. (NASA/JPL-Caltech/SwRI/MSSS)

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.