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Recently resurfaced terrain on Europa may contain compositional fingerprints of the internal ocean comma providing a window into its chemistry and habitability. However comma understanding the relationship between the surface and subsurface chemistries relies on distinguishing endogenic species from those produced via the exogenic bombardment of the surface with Jovian magnetospheric particles. Over the past 20+ years comma numerous studies have sought to disentangle the two comma but have been stymied by either a lack of spectral features across the wavelengths explored comma a lack of sufficient spatial resolution to discern geology from background magnetospheric patterns comma or both. High-spatial-resolution observations in the mid-UV would provide a singular opportunity to build our understanding of these contributions to Europa.s surface comma which will soon be visited by two Flagship-class spacecraft missions--NASA.s Europa Clipper and ESA.s JUICE. Two of Europa.s fewer than ten compositionally diagnostic absorption features (other than those of water ice) lie at mid-UV wavelengths comma including the only feature indicative of the plausibly endogenic SO2 and a feature newly discovered this year that could indicate endogenic salt or an exogenic radiolytic product. We propose a simple slit-scanning program with STIS in G230L to map these features at the high spatial resolution necessary to determine their origins. As neither spacecraft mission carries instrumentation spanning these wavelengths comma HST provides the only opportunity to map Europa across this critical wavelength range comma thereby enhancing the scientific return of the upcoming missions.