As NASA's Juno spacecraft is poised to go closer to Jupiter than any spacecraft ever before, the US space agency has said it is well equipped to counter the extreme radiation environment of our solar system’s largest planet.On the evening of July 4, Juno will fire its main engine for 35 minutes, placing it into a polar orbit around the gas giant. NASA will fly the solar-powered spacecraft the size of a basketball court within 4,667 km of the cloud tops of the planet.During the flybys, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet's origin, structure, atmosphere and magnetosphere.A series of 37 planned close approaches during the mission will eclipse the previous record for Jupiter set in 1974 by NASA’s Pioneer 11 spacecraft from 43,000 km.Getting this close to Jupiter does not come without a price -- one that will be paid each time Juno's orbit carries it toward the swirling tumult of orange, white, red and brown clouds that cover the gas giant."We are not looking for trouble, we are looking for data," said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. "Problem is, at Jupiter, looking for the kind of data Juno is looking for, you have to go in the kind of neighbourhoods where you could find trouble pretty quick," Bolton noted.
The source of potential trouble can be found inside Jupiter itself. Well below the Jovian cloud tops is a layer of hydrogen under such incredible pressure it acts as an electrical conductor.Scientists believe that the combination of this metallic hydrogen along with Jupiter's fast rotation -- one day on Jupiter is only 10 hours long -- generates a powerful magnetic field that surrounds the planet with electrons, protons and ions travelling at nearly the speed of light.The endgame for any spacecraft that enters this doughnut-shaped field of high-energy particles is an encounter with the harshest radiation environment in the solar system."Over the life of the mission, Juno will be exposed to the equivalent of over 100 million dental X-rays," Rick Nybakken, Juno's project manager from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, pointed out.
"But, we are ready. We designed an orbit around Jupiter that minimises exposure to Jupiter’s harsh radiation environment. This orbit allows us to survive long enough to obtain the tantalising science data that we have traveled so far to get,” Nybakken said.Then Juno's orbit will carry the spacecraft below its south pole and away from Jupiter, well beyond the reach of harmful radiation, NASA said.The Juno mission was launched on August 5, 2011 with the primary aim of improving our understanding of the solar system's beginnings by revealing the origin and evolution of Jupiter.With its suite of science instruments, Juno will investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras, according to NASA's mission profile.