On July 4, at 8:18 p.m. PDT, Juno will perform a suspenseful orbit insertion maneuver, a 35-minute burn of its main engine, to slow the spacecraft by about 1,212 miles per hour (542 meters per second) so it can be captured into the gas giant’s orbit.
The entry – dubbed Jupiter Orbital Insertion – is the trickiest part of the mission. Nobody even knows if the spacecraft can survive the radiation and turbulence of being so close to Jupiter. If it succeeds, the $1.1 billion mission will give scientists the most complete data set so far of a planet little understood.
Project scientist Steve Levin of JPL, said: “It’s the biggest and baddest planet in the solar system and it’s got the biggest and baddest radiation and the biggest and baddest magnetic field.
“No spacecraft has ever flown this close to Jupiter. Flown this deep into the radiation belts.”
Juno will announce its safe arrival at Jupiter with the simplest of radio signals: a three-second beep.
“I can tell you when that completes, you’re going to see a lot of celebration,” said Rick Nybakken, Juno’s project manager, “because that means we’ll be in orbit around Jupiter, and that’ll be really cool.”
The spacecraft will orbit Jupiter 32 times, skimming to within 3,100 miles (5,000 kilometers) above the planet’s cloud tops, for approximately one year.
Named after the Roman goddess and wife of Jupiter, Juno is packed with nine instruments capable of peering into the planet’s heart.
Juno’s principal goal is to understand the origin and evolution of Jupiter. This is the first time a spacecraft will orbit the poles of Jupiter, providing new answers to ongoing mysteries about the planet’s core, composition and magnetic fields.
Juno will be the first spacecraft to orbit Jupiter in more than a decade. NASA’s earlier robotic explorer, Galileo, spent eight years viewing and studying the planet. It sent back astounding images of the Jupiter and its many moons.