VUV(115−190 nm) Cassini UVIS data of the surface of Enceladus (square black symbols), Dione (square dark gray symbols), and Rhea (square light gray symbols) compared to a two-fit components (solid red and green lines) of the VUV photoabsorption spectra of solid water and nitrogen dioxide deposited at 22 K (solid light and dark gray lines, respectively). The laboratory ice components are normalized and scaled in the figure for clarity.