Comprehensive Coverage of Europa’s Heterogeneous Surface with JWST NIRSpec

Spectroscopic investigations of Europa’s geologically young, disrupted surface have so far provided our best observational window into the potential composition of its internal ocean. However, a substantial lack of high-quality reflectance spectra beyond 2.5 μm has stymied progress towards constraining the composition of mysterious hydrated materials revealed decades ago by the Galileo mission, understanding the sulfur radiolysis that is expected to pervade the heavily irradiated trailing hemisphere, and searching for critical trace species (e.g., organics)—all of which would inform both the chemistry of the subsurface and the highly altering effects of Europa’s unique irradiation environment. JWST NIRSpec presents the singular opportunity to observe Europa across the entirety of its largely unexplored 2.5–5 μm range at a unique combination of spectral resolution, sensitivity, and spatial resolution, which complements the capabilities of the upcoming Europa Clipper and Juice missions. We present JWST Cycle 2 and 3 NIRSpec observations of Europa (programs 4023 and 9230), which add to the single leading-hemisphere observation from Cycle 1 to provide both the first high-quality, global spectral dataset of Europa’s surface across the entire ~1.7–5.3 μm range and two epochs of observations beyond 2.9 μm. We will discuss how these data reveal the most spectrally detailed view to date of Europa’s chemically distinct trailing hemisphere and enable us to shed new light on endogenic, radiolytic, and temporal processes affecting Europa’s surface chemistry.