Jupiter is thought to be the first planet which formed in the solar system and was first spotted from earth by the Babylonians in the 8th century BC.Little is known about the huge gas giant which is so big it can be seen from Earth without a telescope, and which produces the most spectacular auroras in the solar system.
Scientists are not even sure if there is a solid core beneath its turbulent atmosphere or what drives the enormous magnetic field which surrounds the planet. If the invisible magnetosphere glowed in visible light, it would appear twice the size of the full Moon from Earth.
The Juno spacecraft - named after the Roman goddess and wife of Jupiter - is packed with nine instruments capable of peering into the planet's heart.Spacecraft has spent the past five years travelling the 1.7 million mile journey to reach Jupiter and will arrive on Monday, when it will fire its main thruster to brake, and slip into orbit around the planet.
In the evening of July 4, 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).It will fly 2,600 miles above the cloud tops - 3,000 miles closer to the surface than any other mission has ever achieved.
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. It’s a gamble and the craft has been fitted for a titanium vault to try and protect its sensitive instruments.
Once in Jupiter’s orbit, the spacecraft will circle the Jovian world 37 times during 20 months.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.“We’re going to go in close, get the data and get out. And the first time we go in, that’s the most dangerous.”
Signals from Earth take 48 minutes to reach mission controllers at Nasa’s Jet Propulsion Laboratory (JPL) in Southern California, so they cannot intervene if something goes wrong.
Once the mission is over, Juno will dive into Jupiter’s atmosphere and burn up to avoid accidentally crashing onto one of the planet’s moons.