Speaker
Description
The first three years of JWST scientific operations have provided a treasure trove of new discoveries in our Solar System. Not since Voyager’s Grand Tour have we had a facility capable of spatially-resolved infrared spectroscopy of the four giant planet systems with shared techniques and instrumentation, enabling a comprehensive comparative planetology of the gas and ice giants, their rings, and myriad icy “ocean worlds.” JWST is opening a new window for discovery, accessing spectral domains that were too dark, too cold, or simply overlooked in planetary mission design over previous decades. In this presentation, we review recent discoveries enabled by JWST, from a combination of guaranteed-time, early-release and guest-observer programmes.
For the atmospheres of the giant planets, JWST has detected previously unseen jet streams on Jupiter, revealed the chemical composition of the Great Red Spot and polar vortices, explored seasonally-reversing stratospheric circulations on Saturn, mapped the stratospheric chemistry and circulation of Uranus for the first time, and caught enormous storm activity on Neptune. Emissions from H3+, methane, and carbon monoxide from their ionospheres have revealed delicate wave patterns on Jupiter, never-before-seen structures on Saturn, and the discovery of H3+ on Neptune, providing windows onto magnetospheric processes shaping the wider systems. JWST spectroscopy has revealed the extreme crystallinity of Saturn’s rings, including the “heavy water” fraction, and filtered imaging is revealing radial trends in icy composition of rings and moons in both Ice Giant systems. JWST has also constrained the gases erupting from Io’s powerful volcanism, searched for (but not detected) evidence of Europa plume activity, discovered polar hydrogen peroxide and a tenuous CO2 exosphere on Ganymede, and revealed how CO2 ice is co-located with the chaotic terrains of Europa, implying a connection to the deep surface ocean. These new discoveries will help to shape the exploration from future giant planet missions, such as ESA’s JUICE mission, NASA’s Europa Clipper and Dragonfly, and future endeavours like Uranus Orbiter and Probe.
