Observation of Helium on Mars by EUVE

The Extreme Ultraviolet Explorer (EUVE) presented an opportunity to observe Mars near its opposition earlier this year. Its spectrometer provided the first opportunity to directly measure helium abundance through He I 584 Angstroms emissions. These data will yield important information regarding helium escape from the atmosphere. From this we expect to infer radiogenic heat flux and relative abundances of uranium, thorium and potassium in Mars' interior. Although the observations have been made by the EUVE spacecraft, these data are not available yet. However, there is strong evidence for He I 584 Angstroms emissions in the deep survey data. We will report on the EUVE measurements and their significance in the study of origin and evolution of the solar system.