The distribution of CO${}_2$ on Europa indicates an internal source of carbon

Jupiter’s moon Europa has a subsurface ocean, the chemistry of which is largely unknown. Carbon dioxide (CO${}_2$) has previously been detected on the surface of Europa, but it was not possible to determine whether it originated from subsurface ocean chemistry, was delivered by impacts, or was produced on the surface by radiation processing of impact-delivered material. We map the distribution of CO${}_2$ on Europa using observations obtained with the James Webb Space Telescope (JWST) and find a concentration of CO${}_2$ within Tara Regio, a recently resurfaced terrain. This indicates the CO${}_2$ is derived from an internal carbon source. We propose the CO${}_2$ formed in the internal ocean, though we cannot rule out formation on the surface by radiolytic conversion of ocean-derived organics or carbonates.