Good News for Juno
As revealed in the previous post, the huge magnetic field of Jupiter is produced by the massive westward flow of He3+ ions originating in an ongoing fusion furnace on the solid, frozen, Methane Gas Hydrate surface and exiting through the Great Red Spot. Therefore the magnetic field is not even being generated in the interior of the planet! As a result, the Juno magnetometer is going is going to see large unexpected variations with every rotation of the spacecraft during close approaches. The inner radiation belt is currently believed to comprise electrons circulating eastward at high, even relativistic, velocities. NASA scientists have voiced concern about the effect of these relativistic electrons spawning X-rays which might penetrate the titanium ‘vault’ shielding the electronics and sensors. Surprisingly, there has been no mention of their potential effect on the solar panels which are the only source of power for Juno. Since Juno experienced no power problems on its first close pass, NASA people have already breathed one sigh of relief.
Juno is spin-stabilized to maintain its orientation. The solar panels must be constantly oriented toward the Sun and the high gain antenna toward the Earth, in essentially the same direction. As a result, Juno’s orbit remains in the plane of Jupiter’s terminator with the sunlit side to its right and the dark side to its left, while its spin is used to scan the suite of instrument through the surrounding space and across the surface of the planet in a small zone immediately below the spacecraft. For a good review of all the Juno sensors, go here. It is not clear why NASA decided to orbit from the north pole to the south pole. That decision meant that the surfaces of the solar panels would be blasted by the high speed electrons thought to comprise the inner radiation belts during the science (close) passes.
The massive cloud of He3+ ions, which comprise the inner radiation belt, are the source of the extensive magnetic field of Jupiter but are rotating around the planet in the direction opposite its rotation and the electrons are not there. The good news is, the He3+ ions will be incident on the back side of the solar panels, where they should not do as much damage. Also, since He3+ ions are particles with masses some 5500 times that of the electrons, their velocities are correspondingly less, so the titanium vault which contains the instrumentation should be much more effective in stopping them and preventing problems.
The very best news is going to be difficult for the Juno scientists to accept initially. Far from being the boring sphere of hydrogen and helium with some sort of unreachable core and a tenuous cloud layer of water below the cloud-tops, as currently depicted in every textbook in the world, Jupiter will be revealed as a water world, close to 90 % water and the father of all the terrestrial planets in the solar system and everything on them.