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Blasting off from the Kennedy Space Centre at Cape Canaveral, Florida, on 5 August 2011, NASA’s ‘Juno’ spacecraft has spent the last five years cruising through the solar system, and on 4 July 2016, is set to reach her destination 2 billion miles away from Earth, in Jupiter’s orbit.

Juno, or the Jupiter Near-polar Orbiter, takes her name from the ancient Greco-Roman goddess and wife of Jupiter, stated by mythology as the only soul able to see through the cloak of clouds with which Jupiter masks his mischief. 

Destined to follow her divine namesake, the space probe will peer beneath the gas giant’s layer of cloud in search of a solid planetary core, mapping its magnetic field, and observing auroras within Jupiter’s atmosphere. Over the course of 20 months, Juno will orbit the planet 37 times, collecting important data on water and ammonia in the deep atmosphere, helping scientists to understand the origin and evolution of the Red Giant.

On course for Jupiter

Although Juno still has a long way to go, she has already travelled more than 1.74 billion miles from her launch pad in Florida.  Punching her way through Earth’s atmosphere with the help of an Atlas V rocket, Juno was set onto an escape trajectory to break free of the Earth’s gravitational pull.  Once she had completely separated from the rocket and was well on her way into space, the four tonne probe unfolded the three, 30-foot solar arrays that would keep her onboard batteries charged for the duration of her mission.

Having been launched from Earth by rocket, Juno still needed a little more speed to carry her all the way to Jupiter, and in October 2013, after two years in space, she performed a ‘gravity-assist’ flyby of Earth to give her an extra boost.  By re-entering the Earth’s orbit in what is referred to as a ‘gravitational slingshot’, the probe was able to use the pull of the Earth to its advantage, gathering speed of more than 8,800 miles per hour, and setting her on course for Jupiter.

Nearing her destination

After almost five years of travelling, the time has now come for Juno to drop into orbit around the Red Giant, and start her science in earnest.  As the probe draws close to Jupiter, she will conduct a 35-minute burn of her main engine, shedding speed of over 1000 miles per hour, allowing her to be captured into orbit by Jupiter’s pull.  Here she will circumnavigate the planet twice, with each orbit taking 53 days, before a second engine burn in October 2016 drops the probe in even closer, into a 14-day polar orbit.  Once her mission is complete in February 2018, Juno will fire her engines one last time, knocking her back out of orbit, where she will burn up in Jupiter’s outer atmosphere.

NASA’s Juno spacecraft” by Charly W. Karl is licensed under CC BY-ND 2.0.

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