What happens to the NASA Juno mission

A deep look at and in Jupiter

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January 22, 2021, 6:15 p.m.

The "surface" of Jupiter consists of alternating light and dark bands of gas that harbor strong winds. These winds flow in opposite directions and can reach speeds of more than 100 meters per second. But what happens in the depths below that cannot be seen? Is the interior of the planet just as dynamic as its "surface"?



Jupiter's magnetic field. Concentration of the magnetic field near the equator at the Great Blue Spot. Field lines (gray) show the direction of the field in space, different color depths represent the strength of the magnetic field (with a dark red background strongly positive field, dark blue strongly negative).
(Image: NASA / JPL-Caltech / Harvard / Moore et al.)
Scientists have used small signatures in Jupiter's gravitational field to answer these questions and possibly change our understanding of the internal dynamics of such giant gas planets.

The Juno probe of the US space agency NASA measured the gravitational field of Jupiter precisely. The data reveal details of the structure and dynamics of the planet's interior. Research has shown that at a depth of around 10,000 kilometers, helium, the second most common gas with around ten percent, condenses and forms droplets. When the helium becomes liquid and forms droplets, the neon in it dissolves. The mixed drop continues to sink. Another change then takes place at a depth of more than 13,000 kilometers under the cloud cover. At temperatures of around 5,000 ° C and pressures of one to two million atmospheres, the surrounding liquid hydrogen suddenly turns into a liquid metal. In no laboratory can the enormous forces that are necessary for the formation of the metallic-liquid hydrogen be generated.

What properties this exotic state has and what it looks like can only be guessed at. It is clear that the actually non-conductive gas hydrogen suddenly turns into a conductive liquid. As with a metal, electrons can flow relatively freely in this mixture and thus cause electrical currents.



Jupiter in visible light and infrared wavelengths.
(Image: NASA / IRTF / JPL-Caltech / NAOJ / A. Wesley / A. Kazemoto / C. Go)
But even the helium droplets cannot withstand the hellish conditions inside Jupiter for long. At more than 10,000 ° C and at a pressure of several million atmospheres, the liquid helium also finally turns into a metal. Once it has become a metal, it forms a mixture with the likewise metallic-liquid hydrogen, which can be compared to a metal alloy. The metallic mixture of hydrogen and helium deep inside Jupiter is quite exotic, but at the same time it finally provides an explanation for another long-known peculiarity of Jupiter, the magnetic field of the gas giant.

The mixture of metallic-liquid hydrogen and helium probably takes on the role of the dynamo in the interior of the planet, and acts like the earth's core made of solid and liquid iron. The rotation at different speeds in different regions and the ascending and descending convection currents of the conductive liquids generate the enormous magnetic field forces of the gas planet.



The Great Red Spot, which has been swirling in Jupiter's atmosphere for centuries, was captured in two close-ups on JunoCam. The huge storm swirls through Jupiter's atmosphere and creates the turbulent currents to the west. On the west side of the Great Red Spot itself, a strip of red material is peeled off the periphery. This is a new, common phenomenon that was first observed in ground-based data in 2017.
(Image: NASA / JPL-Caltech / SwRI / MSSS Image processing by Kevin M. Gill, © CC BY)
The convection currents inside the planet presumably reach the surface. With the refined measurements of the Jupiter gravitational field by space probes and improved methods for modeling the planetary structure, the researchers could not clarify whether the convection currents inside are related to the banded appearance of the surface.

It could be that the bands are just a surface phenomenon and that the convection inside follows a completely different pattern than on the surface. Alternatively, what can be seen on the surface could be an extension of deep-lying convective currents that carry energy from within.

Given the complexity of planets, comparative planetary research has become an essential aspect of studying these astrophysical objects. The data on Jupiter could be compared with the results from the gas giant planet Saturn.

NASA's Cassini mission to Saturn, which ended in 2017, provided a Juno-like data set for Saturn's gravitational field that is now being analyzed. Since Saturn has lower internal pressures than Jupiter, the atmospheric winds should be able to extend much deeper into Saturn's interior before hydrogen ionization and the associated drag forces take control. If it were possible to put together a consistent physical picture for the two gas giants in our solar system, this would significantly deepen the understanding of the internal dynamics of this class of astrophysical objects.

Publication:
A deeper look at Jupiter

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Source: NASA, Nature

Author: Raumfahrer.net editors