Mapping Ganymede's time variable aurora in the search for a subsurface ocean A very exciting, unresolved question about Jupiter’s moon Ganymede is whether Ganymede harbors a saline subsurface water ocean under its icy crust. A saline, electrically conductive water ocean will modifiy Ganymede's magnetic field enviorment and thus also the locations of Ganymede's northern and southern auroral ovals. Without an ocean, Ganymede's auroral ovals will rock by ~10 degrees towards and away from Jupiter within 5.25 hours. However, with an ocean the shift will be up to only ~4 degrees. We propose two visits of five consecutive STIS orbits at eastern elongation to monitor and resolve with sufficient precision the shift in locations of Ganymede's auroral ovals to determine wheter an ocean is present on Ganymede. Addressing this question is timely as NASA/ESA are planing a Jupiter system mission including a Ganymede orbiter with the objective to characterize Ganymede as potential habitat.
We propose 5 consecutive orbits in two visits (10 orbits total) with STIS to observe Ganymede’s auroral ovals at eastern elongation. With STIS we will be able to separate reflected sun light on Ganymede’s surface from the two oxygen lines OI 1356 Å and OI 1304 Å, which are emitted from Ganymede’s oxygen atmosphere along its auroral ovals. We propose to center the disk of Ganymede (maximum diameter ~2.0 acrseconds) to obtain a symmetric field of view around the disk of Ganymede. We are requesting a total of 10 orbits at eastern elongation, i.e. for the leading/downstream (longitude 90 degrees) hemisphere of Ganymede. The eastern elongation has been previously observed by STIS within a time span of two hours, only (ID: 8224). We also request that each of the two visits starts within a time window of one hour prior to when Ganymede is at 20 or 200 degree system three longitude (i.e. in a coordinate system rotating with Jupiter and describing the orientation of Jupiter’s magnetic field). In this way we make certain that we cover both extreme locations of Ganymede’s auroral ovals, i.e. the maximum rocking of the ovals within each visit. Measuring the maximum degree of the rocking is the key observational objective of our proposal. SOLAR SYSTEM 12 false 0.0 0.0 false false false false AVAILABLE SOLAR SYSTEM SATELLITE Jovian satellite STD=JUPITER STD=GANYMEDE OLG OF JUPITER BETWEEN 330 30, OLG OF GANYMEDE FROM EARTH BETWEEN 70 110, CML OF JUPITER FROM GANYMEDE BETWEEN 179 100 EARTH SOLAR SYSTEM SATELLITE Jovian satellite STD=JUPITER STD=GANYMEDE OLG OF JUPITER BETWEEN 330 30, OLG OF GANYMEDE FROM EARTH BETWEEN 70 110, CML OF JUPITER FROM GANYMEDE BETWEEN 170 100 EARTH SOLAR SYSTEM SATELLITE Jovian satellite STD=JUPITER STD=GANYMEDE OLG OF JUPITER BETWEEN 330 30, OLG OF GANYMEDE FROM EARTH BETWEEN 70 110, CML OF JUPITER FROM GANYMEDE BETWEEN 11 287 EARTH SOLAR SYSTEM SATELLITE Jovian satellite STD=JUPITER STD=GANYMEDE OLG OF JUPITER BETWEEN 296 40, OLG OF GANYMEDE FROM EARTH BETWEEN 70 111, CML OF JUPITER FROM GANYMEDE BETWEEN 184 112 EARTH SOLAR SYSTEM SATELLITE Jovian satellite STD=JUPITER STD=GANYMEDE OLG OF JUPITER BETWEEN 296 40, OLG OF GANYMEDE FROM EARTH BETWEEN 69 110, CML OF JUPITER FROM GANYMEDE BETWEEN 11 305 EARTH STIS/FUV-MAMA Spectroscopic No No G140L 1425 STIS/FUV-MAMA Spectroscopic No No G140L 1425 Using ephemeris for target 12244-01-GANYMEDE1A ephemeris data for target 12244-01-GANYMEDE1A does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 10.182 to 12.060. ephemeris interval: 10.212 to 12.214 Timing link suitability includes constraints ([Group (01 03) Within 90.0 days]) The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. 1284622761000 289.4930468119701 (Tic-Visit :proposal-id 12244 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "31-Aug-2010 14:15:16.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1497152 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12244 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 12244 :visit-id "01" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2756 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2867 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 3 :pcs-time 333 :si-vis-utilization 2756 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2867 :al-overhead-at-end 0 :internal-dur-at-end 2401 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 627 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) false 5 0 Execute either visit 01 or visit 02 Using ephemeris for target 12244-02-GANYMEDE1B ephemeris data for target 12244-02-GANYMEDE1B does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 10.182 to 12.060. ephemeris interval: 10.212 to 12.214 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12244 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "12-Aug-2010 11:44:01.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1479024 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12244 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12244 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2726 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "02" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) false 5 0 Execute either visit 01 or visit 02 Using ephemeris for target 12244-03-GANYMEDE2A ephemeris data for target 12244-03-GANYMEDE2A does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 10.182 to 12.060. ephemeris interval: 10.212 to 12.214 Timing link suitability includes constraints ([Group (01 03) Within 90.0 days]) The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. 1290196137000 65.9871991680626 (Tic-Visit :proposal-id 12244 :visit-id "03" :proposal-version -1 :trans-version "20100505" :date "12-Aug-2010 11:44:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1479024 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12244 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12244 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2726 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "03" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "03" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "03" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) false 5 0 Execute either visit 03 or visit 04 Using ephemeris for target 12244-04-GANYMEDE2B ephemeris data for target 12244-04-GANYMEDE2B does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 10.182 to 12.060. ephemeris interval: 10.212 to 12.214 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12244 :visit-id "04" :proposal-version -1 :trans-version "20100505" :date "12-Aug-2010 11:44:40.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1479024 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12244 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12244 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2726 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "04" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "04" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "04" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "04" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2837 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) false 5 0 Execute either visit 03 or visit 04 Repeat of failed visit 01. (Tic-Visit :proposal-id 12244 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "31-Aug-2010 14:15:16.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1497152 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12244 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 12244 :visit-id "01" :obset-id "A1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2756 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2867 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 3 :pcs-time 333 :si-vis-utilization 2756 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2867 :al-overhead-at-end 0 :internal-dur-at-end 2401 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12244 :visit-id "01" :orbit-number 5 :pcs-time 222 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 627 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3090.0 :pcs-gap 0 ) false 5 0 Execute either visit 01 or visit 02