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According to Stencel, this particular mission was designed to get the “biggest bang for the buck.” He says there are three major goals for going back to Jupiter: Finding out how big Jupiter’s central core mass actually is, determining the nature of water in the atmosphere and learning more about the very large radiation fields.

“If we find out the planet doesn’t have the density theorists tell us it does, that would be a surprise and would affect the whole theory of how planets form in the first place,” Stencel says. “Jupiter, being the biggest planet in the solar system, that’s got to be telling us the story of the history of the solar system itself. If it turns out Jupiter is denser than lead, that would be a surprise. If it turns out Jupiter is the consistency of a Hostess Twinkie cake, that would be a surprise.”

The plan for Juno is to orbit close to the poles��so that NASA can get a good measurement of the density structure. That measurement, however, will take some time to gather. Stencel points out that these things won’t happen overnight, as Juno will go through 53-day cycles (days close and far from the planet) during its orbit, which helps minimize the radiation damage from the planet. The first 53 days will be devoted to instrument testing to ensure the probe is functioning properly.