The significant impact of Jupiter's magnetic field

PIA19048 realistic color Europa mosaic 

Photo credit: NASA/JPL-Caltech/SETI Institute

 

Who is Europa?

In fews words, Europa is a small satellite of Jupiter, the sixth by distance and the second among the Galilean satellites (Io, Europa, Ganymede).
 
Size: 3,121 kilometers (one-fourth the diameter of Earth)
Temperature: - 150°C
Atmosphere: mainly composed of O2
Structure: Its surface is composed of ice and is the slickest of all the solar system. In the 1990’s, the Galileo space mission revealed the presence of deep liquid ocean under the ice ; in September 2016, the Hubble Space Telescope (NASA) observed water geysers on its surface.

These discoveries triggered questions about a potential life in Europa. The NASA is planning to investigate this hypothesis thanks to a new space mission that might be launched in 2020-2030.


Europa awakens the curiosity of the scientific community! 

If data from space missions got evidences of the presence of oceans in the moons of Jupiter (awaiting confirmation by a future mission), we didn’t have much information about the mechanisms and the geological consequences on these moons and more particularly on Europa.

 

The influence of Jupiter’s magnetic field on ocean dynamics : a first and huge step in the understanding of Europa 

Ludovic Petitdemange, CNRS researcher at LERMA (Laboratoire d’Études du Rayonnement et de la Matière en Astrophysique et Atmosphères) and Christophe Gissinger CNRS researcher at LPENS (Laboratoire de Physique de l’École Normale Supérieure), started their research about Europa in 2016.

They focused their research on the oceanic motions and highlighted a physical phenomenon still ignored by scientists.

To reach their goals, they did numerical simulations of Europa’s interior (a model) thanks to data from space missions. They found that Jupiter influences the dynamics of oceans : « Jupiter’s magnetic field generates a retrograde oceanic jet at the equator, which may influence the global dynamics of Europa’s ocean and contribute to the formation of some of its surface features by applying a unidirectional torque on Europa’s ice shell. »

 

image paper

 

Fig.1 shows that the rotation of Jupiter’s magnetic field induces a planetary scale recirculation, and generates strong upward and downward turbulent motions at the equator (Fig. 1c). But the most striking feature is the generation of a powerful oceanic jet propagating westward (Fig. 1a and 1b), and localized in the moon’s equatorial region.

More detailed information in the scientific paper here


Next research steps

These results brought new ideas to the scientists and raised new questions. Ludovic and Christophe are now planning to explain the link between the liquid and the geological features observed on Europa. According to them, It would also be interesting to do simulations which cover all the parameters (it means a more detailed model of Europa) such as Jupiter's tidal effect on Europa because we don’t know yet precisely how theses forces are acting/reacting together.


>>> Congratulations Ludovic and Christophe & Good luck! We're waiting to hear from this great astrophysics project!



References:

Gissinger, C., Petitdemange, L., 2019. A magnetically driven equatorial jet in Europa’s ocean. Nature Astronomy. https://doi.org/10.1038/s41550-019-0713-3
Article grand public, National Geographic: https://www.nationalgeographic.fr/espace/2019/03/le-champ-magnetique-de-jupiter-fragilise-sa-lune-europe
About Europa in NASA website: https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/