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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.近期在木卫二(Europa)表面重新出露的区域可能留存有其内部海洋的成分指纹，为我们探究该海洋的化学组成与可居住性提供了关键窗口。然而，要厘清木卫二表面与次表层化学之间的关联，需要区分内生化学物质与木星磁层粒子通过外源性轰击表面所产生的外源物质。过去20余年来，诸多研究试图厘清这两类物质的来源差异，但均受限于两大瓶颈：一是现有探测波段下缺乏足够的光谱特征，二是空间分辨率不足，无法有效区分地质特征与背景磁层分布模式，或是两者兼而有之。中紫外(mid-UV)波段的高空间分辨率观测，将为我们理解这些成分对木卫二表面的贡献提供独一无二的契机——而即将有两艘旗舰级航天器造访木卫二：美国国家航空航天局(NASA)的欧罗巴快帆(Europa Clipper)与欧洲空间局(ESA)的JUICE探测器。木卫二仅有的不到10项可用于成分诊断的吸收特征（水冰(water ice)特征除外）中，有两项位于中紫外波段：其一为唯一可指示潜在内生二氧化硫(SO2)的特征，其二为今年新发现的、可能指向内生盐类或外源性辐射分解产物的特征。我们提议利用哈勃空间望远镜(Hubble Space Telescope, HST)搭载的太空望远镜成像摄谱仪(Space Telescope Imaging Spectrograph, STIS)的G230L模式，开展一项简易狭缝扫描计划，以足够高的空间分辨率绘制这些特征的空间分布，进而确定其起源。由于上述两艘旗舰航天器均未搭载覆盖该关键波段的探测仪器，哈勃空间望远镜将成为目前唯一能够在这一波段范围内测绘木卫二的平台，从而显著提升后续任务的科学回报价值。