Jupiter’s hiding something. We can see the cloud tops. We can monitor the planet’s intense winds and observe its enormous cyclonic and anticyclonic storms like the Great Red Spot. But we don’t know what’s happening on the inside.
Maybe all the meteorological activity we see is only skin-deep. Maybe beneath the tumultuous “surface” lies a calm and tranquil atmosphere/ocean of gaseous/liquid hydrogen.
Or perhaps Jupiter’s interior is a violent and chaotic place. Perhaps storms like the Great Red Spot are driven by as yet unknown forces that extend deep into the planet’s innermost layers.
How can we settle the matter?
In July of 2016, NASA’s Juno spacecraft will enter a high eccentricity polar orbit around Jupiter. Jupiter’s upper atmosphere includes clouds of water (yes, you read that right… there’s water on Jupiter!). Using a microwave radiometer, Juno will attempt to figure out just how far down the water goes.
Also, as Juno skims near Jupiter, NASA will pay close attention to how Jupiter’s gravity affects the spacecraft. Subtle changes in Juno’s velocity will reveal variations in Jupiter’s gravity, indicating variations in the planet’s density. This technique, called gravity mapping, has been used to study the interiors of other planets, including Earth.
Juno also carries a magnetometer (in the illustration above, it’s that pointy thing connected to one of the solar panels). Since Jupiter’s magnetic field is generated by super pressurized metallic hydrogen and perhaps other metallic elements in the planet’s core, data from the magnetometer should give us a clearer understanding of conditions at the center of Jupiter.
Personally, I like the image of Jupiter’s chaotic surface activity concealing a deep, inner calm. It makes the planet sound really Zen. But we’ll have to wait until 2016 to find out if Jupiter is hiding a violent or tranquil interior.
P.S.: One of Juno’s instruments is named JEDI (short for Jovian Energetic particle Detector Instrument). Because NASA engineers can’t design a spacecraft without making at least one Star Wars reference.