EUROPAS SURFACE-COMPOSITION AND SPUTTER-PRODUCED IONOSPHERE

The efficient sputtering and decomposition of Europa's regolith by ene rgetic charged particles produces an atmosphere representative of its surface composition. In addition to O-2 and H-2 from the decomposition of ice, we show that molecules representative of organics and salts w ill be present in ionic form at levels detectable using an ion mass sp ectrometer on an orbiting spacecraft. Such an instrument can also meas ure isotope ratios to determine surface age.