Astronomy
Solar System

CO2 in Europa’s Ocean

Published on 27 September 2023

The James Webb space telescope has just identified the source of the CO2 detected on the surface of Jupiter's satellite Europa. It has not been introduced by meteorites or comets but has in fact come from its ocean located under its crust of ice. The source could be relatively recent.

The James Webb space telescope has just identified the source of the CO2 detected on the surface of Jupiter’s satellite Europa. It has not been introduced by meteorites or comets but in fact has come from its ocean located under its crust of ice. The source could be relatively recent.

CO2 IN THE OCEAN?

We already knew that there was CO2 on the surface of Europa. But what we didn’t know was where it came from. Was it from external sources, such as meteorites or comets … or from Jupiter ‘s moon itself? Two teams of American astronomers therefore decided to point the James Webb Space Telescope (JWST) there and use its NIRSpec spectrograph and its NIRCam infrared camera to understand where this carbon dioxide came from.

What emerged from their study, published in the journal Science, is that this CO2 is mainly concentrated in an area called the Tara Regio, a quite young and recently renewed region, 1800 km in diameter. The source is therefore not external but rather internal to the ocean of salty liquid water located under the icy crust. The CO2 is then released into Europa’s thin atmosphere before being eliminated. For such gas concentrations to be observed, a continuous supply of CO2 is therefore required and the source must be relatively recent.

CO2 has already been identified on Mars, Venus and Enceladus, a satellite of Saturn. On Earth, carbon dioxide is a chemical element essential to life which allows plants to carry out the photosynthesis process. This discovery reinforces the hypothesis that Europa’s ocean could be habitable and host life-forms.

Internal structure of Jupiter’s icy moon, Europa. It has a crust of ice, then an ocean of salty liquid water. The ocean floor is rocky and the core is metallic. @NASA/JPL

This graphic shows a map of the surface of Europa using NIRCam and composite maps derived from NIRSpec data. The white pixels represent carbon dioxide in the large-scale region of disturbed chaotic terrain known as the Tara Regio.
@Geronimo Villanueva (NASA/GSFC), Samantha Trumbo (Cornell Univ.), NASA, ESA, CSA, Alyssa Pagan (STScI)

TWO PROBES TO EUROPA

In the coming years, two missions will allow us to learn more about Europa. The European probe Juice (Jupiter Icy Moon Explorer), launched on April 14, will fly over it twice before placing itself in orbit around Ganymede, another icy moon with high potential habitability. The onboard MAJIS instrument should make it possible to observe the same wavelengths but with a much better resolution. In October 2024, NASA plans to launch the Europa Clipper probe around Jupiter’s icy moon.