Europa's Composition as Revealed by its Atmosphere

0 Assigned ID: 549 ----- Attempting Submission 1 (Fri Apr 11 16:04:09 GMT 2014) ----- HST Phase I Proposal 549 (Europa COS_c22.apt) successfully submitted. INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS Added COS ETC run numbers per emails from Hugues Sana December 2014. Note that I do not want to add an ACQ/PEAKD to the acquisition, as I do not need precise centering. I have checked 8 data from 8 Galilean satellite acquisitions with COS [3 of Callisto from program 11535; 1 of Io from program 11538; 1 of Europa from program 11539; and 3 of Io from program 12041]. I have not seen any ACQ/SEARCH that failed, and all the ACQ/PEAKDs found the highest number of counts in the 1st dwell point. So the ACQ/PEAKD did not add any value in any of the above acquisitions. Therefore I woud like to stick with just the ACQ/SEARCH. 458991272 ----- Attempting Submission 1 (Thu Jul 24 15:45:20 GMT 2014) ----- HST Phase II Proposal 13803 (Europa COS_c22_final.apt) successfully submitted. ----- Attempting Submission 2 (Thu Jul 24 19:57:39 GMT 2014) ----- HST Phase II Proposal 13803 (Europa COS_c22_final.apt) successfully submitted. ----- Attempting Submission 3 (Mon Jan 05 21:03:32 GMT 2015) ----- I incorporated the FP-POS recommendations from the CS, but still can't get rid of the warning about inefficient use of FP-POS. Don't understand why it persists. Europa's Composition as Revealed by its Atmosphere The two main sources of Europa's tenuous atmosphere, surface sputtering and plumes, imply that Europa's surface and sub-surface composition are directly reflected by the composition of its atmosphere. Recent detection of water vapor plumes at Europa makes it more likely that the atmosphere contains important trace species that are diagnostic of the sub-surface ocean composition. We will perform a sensitive search for trace species via electron excited emissions in the far-ultraviolet with the Cosmic Origins Spectrograph, in order to constrain the composition of the ice-ocean-rock system and better understand the potential habitability of the satellite. HST spectroscopic measurement of trace species is one of the only techniques presently available to meaningfully constrain Europa's composition. We will perform deep spectroscopic integrations of Europa using COS gratings G130M and G160M to search for trace species in Europa's atmosphere. To minimize contamination from Earth's geocoronal emission, we request that the observations be performed near Jupiter opposition. We are targeting the Europa trailing hemisphere, which potentially has a higher abundance of trace species contaminating the surface than the leading hemisphere. We will cycle through the four FP-POS positions with both gratings. Precise centering is not required, so we will utilzie only an acq/search. The acq/search exposure time pf 3 s is based on the well known trailing hemisphere albedo of Europa at 2700 A (about 10%), and the counts obtained in the COS acq/search and acq/peakd acquitisions of Europa in program 11353. SOLAR SYSTEM 6 Regular false false false false false SUPPORTED SOLAR SYSTEM SATELLITE Europa's trailing hemisphere STD=JUPITER STD=EUROPA SEP OF EUROPA-TRAILING JUPITER FROM EARTH GT 30", SEP OF EUROPA-TRAILING CALLISTO FROM EARTH GT 10", SEP OF EUROPA-TRAILING IO FROM EARTH GT 10", SEP OF EUROPA-TRAILING GANYMEDE FROM EARTH GT 10", OLG OF EUROPA-TRAILING BETWEEN 240 300, OLG OF JUPITER BETWEEN 330 20 EARTH COS/FUV Spectroscopic No No G130M 1327 COS/FUV Spectroscopic No No G160M 1589 1406231656439 Using ephemeris for target 13803-01-EUROPA-TRAILING The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. 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