0 Assigned ID: 933 ----- Attempting Submission 1 (Fri Apr 05 23:17:40 GMT 2019) ----- HST Phase I Proposal 933 (EuropaCallistoProposal.apt) successfully submitted. Receipt: # 933-1 ----- Attempting Submission 2 (Fri Apr 05 23:38:19 GMT 2019) ----- COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details. 0 ----- Attempting Submission 1 (Tue Jul 23 15:15:07 GMT 2019) ----- All warnings are just generic statements about COS calibration limitations for extended sources. We don't need highly accurate flux values to compare the spectral shapes of Europa and Callisto. Constraining the UV-absorbing material on Jupiter's icy moons through comparative reflectance spectroscopy The far-UV (FUV) spectrum of water ice contains a sharp absorption edge around 165 nm, becoming highly reflective at wavelengths longer than this. This feature has been observed in lab measurements and in Cassini UVIS observations of Saturn's moons. However, Ganymede's FUV spectrum (derived from COS G140L observations in 2014) does not exhibit a sharp increase in reflectance near 165 nm as expected; instead, the reflectance gradually increases at wavelengths >170 nm, implying that there is a UV-absorbing contaminant present. Observations of Europa just outside of the critical region around 165 nm suggest that the water ice feature may be similarly modified there, and Callisto's reflectance in this region is currently unknown. We therefore propose to observe Europa and Callisto using COS G140L, to determine whether the spectral reflectance of the two moons close to the 165 nm water ice edge is modified similarly to Ganymede's. We will use four HST orbits to observe the leading and trailing hemispheres of each satellite. The leading and trailing hemispheres of the Galilean moons experience different radiation environments, with Jovian magnetospheric plasma predominantly impacting the trailing hemispheres. By comparing the observed reflectance of Jupiter's icy moons, and by assessing differences between the leading and trailing hemispheres, we can investigate whether a single contaminant modifies the spectra of all three satellites, and whether this may be a product of radiolytic processing of the surfaces by the Jovian plasma. The orbital leading and trailing hemispheres of Europa and Callisto will each be observed in four single orbit visits, using the COS G140L grating with central wavelength setting 1280. We have requested observations within +/- 6 weeks of Jupiter opposition to maximize the angular size of the targets, but if scheduling is a problem we can relax this slightly. We plan to use the same target acquistion strategy as used in program 13328 for FUV observations of Ganymede. That program followed the ACQ/SEARCH with a COS/NUV ACCUM exposure to verify Ganymede's position in the aperture. We have not included this step because we do not require precise centering information, and because programs 13803 and 14903 successfully observed Europa with COS following a single ACQ/SEARCH exposure. For ETC target acquisition runs we used surface brightness values from JPL Horizons (Europa: 5.2 Vmag/arcsec2; Callisto: 6.5 Vmag/arcsec2) and scaled them based on the difference between the visible and NUV albedos of Europa and Callisto. Europa's visible albedo is ~67%, and its average albedo in the 240-320 nm range is ~ 13% (trailing hemisphere) to ~27% (leading hemisphere) [Nelson et al. 1987], so it is ~1 to 1.8 magnitudes dimmer in the NUV. Callisto's visible albedo is ~22%, its average albedo in the 240-320 nm range is ~5.2% (leading hemisphere) to ~ 7.5% (trailing hemisphere), and it is therefore ~1.2 to 1.6 magnitudes dimmer in the NUV. ETC runs for the science exposures used Ganymede COS G140L data from Program 13328 as input spectra. Europa may be up to ~1.6 x brighter than Ganymede at wavelengths >160 nm, based on the ratio of their NUV albedos, but even if this is the case the maximum count rate will be well below the COS FUV count rate limits. This team proposing these observations has significant experience in HST UV observations, UV studies of icy moons, and spectral reflectance models. PI Molyneux led a Cycle 25 Program (15111) to observe the UV reflectance of Trojan asteroids, has contributed to several additional UV HST programs as a Co-I, and has experience processing and analyzing COS G140L observations of Ganymede [Molyneux et al., 2018]. Co-I Becker similarly has UV HST experience as both PI and Co-I, and has experience in the analysis of UV reflectance data of Europa [Becker et al., 2018]. Co-I Retherford is the PI of the Europa-UVS instrument under development for Europa-Clipper, has led and collaborated on multiple HST UV proposals and has considerable experience in the analysis of UV observations of the Galilean moons. Co-I Royer is an expert in UV reflectance models of icy surfaces, previously focusing on Cassini UVIS observations of Saturn's moons. Solar System 6 false false true false false false false SUPPORTED SOLAR SYSTEM YES SATELLITE SATELLITE EUROPA STD=JUPITER STD=EUROPA NOT OCC OF EUROPA-EAST BY JUPITER FROM EARTH, SEP OF EUROPA-EAST IO FROM EARTH GT 10", SEP OF EUROPA-EAST GANYMEDE FROM EARTH GT 10", SEP OF EUROPA-EAST CALLISTO FROM EARTH GT 10", OLG OF EUROPA-EAST BETWEEN 75 105 EARTH SOLAR SYSTEM YES SATELLITE SATELLITE EUROPA STD=JUPITER STD=EUROPA NOT OCC OF EUROPA-WEST BY JUPITER FROM EARTH, SEP OF EUROPA-WEST IO FROM EARTH GT 10", SEP OF EUROPA-WEST GANYMEDE FROM EARTH GT 10", SEP OF EUROPA-WEST CALLISTO FROM EARTH GT 10", OLG OF EUROPA-WEST BETWEEN 255 285 EARTH SOLAR SYSTEM YES SATELLITE SATELLITE CALLISTO STD=JUPITER STD=CALLISTO NOT OCC OF CALLISTO-EAST BY JUPITER FROM EARTH, SEP OF CALLISTO-EAST IO FROM EARTH GT 10", SEP OF CALLISTO-EAST EUROPA FROM EARTH GT 10", SEP OF CALLISTO-EAST GANYMEDE FROM EARTH GT 10", OLG OF CALLISTO-EAST BETWEEN 75 105 EARTH SOLAR SYSTEM YES SATELLITE SATELLITE CALLISTO STD=JUPITER STD=CALLISTO NOT OCC OF CALLISTO-WEST BY JUPITER FROM EARTH, SEP OF CALLISTO-WEST IO FROM EARTH GT 10", SEP OF CALLISTO-WEST EUROPA FROM EARTH GT 10", SEP OF CALLISTO-WEST GANYMEDE FROM EARTH GT 10", OLG OF CALLISTO-WEST BETWEEN 255 285 EARTH COS/FUV Spectroscopic No No G140L 1280 COS/FUV Spectroscopic No No G140L 1280 COS/FUV Spectroscopic No No G140L 1280 COS/FUV Spectroscopic No No G140L 1280 /Users/pmolyneux/Documents/OP-cache/EuropaCallistoPhase2-v01.xml Using ephemeris for target 15868-01-EUROPA-EAST The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. Europa leading hemisphere (Tic-Visit :proposal-id 15868 :visit-id "01" :proposal-version -1 :trans-version "20190514" :date "22-Jul-2019 12:34:34.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 191424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15868 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15868 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 341 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 ETC run assumes surface brightness of 6.1 Vmag/arcsec2 /Users/pmolyneux/Documents/OP-cache/EuropaCallistoPhase2-v02.xml Using ephemeris for target 15868-02-EUROPA-WEST The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. Europa trailing hemisphere (Tic-Visit :proposal-id 15868 :visit-id "02" :proposal-version -1 :trans-version "20190514" :date "22-Jul-2019 12:34:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 191424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15868 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15868 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 341 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 ETC run assumes surface brightness of 7.0 Vmag/arcsec2 /Users/pmolyneux/Documents/OP-cache/EuropaCallistoPhase2-v03.xml Using ephemeris for target 15868-03-CALLISTO-EAST The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. Callisto leading hemisphere (Tic-Visit :proposal-id 15868 :visit-id "03" :proposal-version -1 :trans-version "20190514" :date "22-Jul-2019 12:34:16.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 174048 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15868 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15868 :visit-id "03" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2739 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 ETC run assumes surface brightness of 8.2 Vmag/arcsec2 /Users/pmolyneux/Documents/OP-cache/EuropaCallistoPhase2-v04.xml Using ephemeris for target 15868-04-CALLISTO-WEST The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. Callisto trailing hemisphere (Tic-Visit :proposal-id 15868 :visit-id "04" :proposal-version -1 :trans-version "20190514" :date "22-Jul-2019 12:34:03.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 174048 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15868 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15868 :visit-id "04" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2739 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 ETC run assumes surface brightness of 7.6 Vmag/arcsec2