JUNO: The mission that rewrote the story of Jupiter

As NASA's Juno mission nears its end, Nicky Jenner explores the secrets it has uncovered about the Solar System's largest and most enigmatic world

- Nicky Jenner

It's difficult to fully grasp the enormity and extremity of Jupiter.

The planet - a striped behemoth of swirling gas with around 100 moons, one of which is larger than Mercury - dominates the Solar System, flooding space with its magnetism and exerting its powerful gravity over everything nearby. The planet contains most of the 'stuff' left over after the birth of the Sun, and is so influential that it's played a central role in shaping our patch of space into the system we see today.

It's no wonder that we've had Jupiter firmly in our sights from our earliest forays into space exploration. We first sent spacecraft there in the 1970s with NASA's Pioneer and Voyager probes, which swung past the planet and observed it from space.

NASA's Galileo probe stayed a little longer, taking up residence around Jupiter from 1995 to 2003, and was shortly succeeded by another NASA orbiter that's still peering down at the gas giant today: Juno.

A gift to Jupiter fans

“NASA sends a probe to deep space - that is, beyond Mars - every decade. Juno was selected for this in 2005,” says Juno scientist John Leif Jørgensen of the Technical University of Denmark. “Previous probes had only been transitory or orbited Jupiter's equator, offering very limited views of high latitudes. But higher latitudes contain much more information about a planet's morphology, surface and interior, so we proposed a polar orbiter.”

Such an orbit is subject to harsher radiation and is more complex to operate - but it's been worth it. “With Juno, practically all possible observations have become superior to those offered by any other mission."