STIS spectroscopy of Amalthea and Thebe: Surface composition and interactions with Jupiter's magnetosphere and rings

0 Assigned ID: 5491 ----- Attempting Submission 1 (Tue Mar 26 15:03:17 GMT 2024) ----- The number of orbits used exceeds the number allocated Added target acquisitions to Visits 3B and 4B in case we go ahead with the decision to split Visits 03 and 04 into separate orbits. -166892838 ----- Attempting Submission 1 (Thu Aug 08 20:14:55 GMT 2024) ----- ----- Attempting Submission 2 (Mon Dec 08 20:13:13 GMT 2025) ----- Number of orbits currently exceeds number awarded because we are considering alternatives for visits 03 and 04 and haven't deleted the original versions yet STIS spectroscopy of Amalthea and Thebe: Surface composition and interactions with Jupiter's magnetosphere and rings Jupiter's inner moons are an important aspect of the Jupiter system, acting and sources and sinks for the rings and providing clues to the evolution of the system as a whole. However, very few spectral observations of the inner satellites have been performed to date, and the only previous observations by HST, which were obtained using the Faint Object Spectrograph, suffer from instrumental artifacts that hamper their interpretation. We propose new STIS observations of the largest inner moons, Amalthea and Thebe, to investigate their surface compositions and search for signatures of interactions with the Jovian magnetospheric plasma. We will also constrain their grain sizes, providing insight on the contribution of electrostatic lofting to Jupiter's gossamer rings. We plan to observe Thebe using the G230L and G430L gratings, to search for absorption features related to sulfur species and reflectance peaks associated with small grains. At Amalthea, we will perform similar observations and also use G750L to search for a 0.7-micron absorption related to hydrated silicates, constraining the origin of a 3-micron absorption feature previously observed on the trailing hemisphere. The proposed observations are highly relevant to future observation of the Jupiter system by JUICE, providing the opportunity to investigate temporal variations and filling a gap between the JUICE-UVS and MAJIS spectrographs. Our program aims to obtain STIS spectra of Jupiter's largest inner moons, Amalthea and Thebe, from the mid-UV through visible wavelengths. We will use two orbits to observe the leading and trailing hemispheres of Thebe. Each orbit includes one observation using STIS G230L and one using STIS 430L. For Amalthea we require two 2-orbit visits: one visit to observe the leading hemisphere and one to observe the trailing hemisphere. The first orbit of each visit is a stare using the STIS G230L mode for the longest time possible. The second orbit uses the STIS G430L and G730L modes, but with a narrower slit which we step across Amalthea in three steps to constrain any spatial variability in surface composition. For ETC runs we used a Castelli-Kurucz G2V model to represent the expected reflected solar spectrum. We used the largest angular diameters expected during Cycle 32 (0.084 arcsec for Amalthea; 0.039 arcsec for Thebe) and Vmag/arcsec^2 values from JPL Horizons. We have requested observations within 8 weeks of Jupiter opposition on 7 Dec 2024 to maximize the apparent size and brightness of both objects. This is particularly important for Thebe, which is the smaller, dimmer object. PI Pippa Molyneux has experience planning and analyzing STIS observations of solar system objects including Jupiter's Galilean satellites and the Jupiter Trojan binary system (617) Patroclus. Her research involves producing Hapke reflectance models, which she has previously used to constrain the compositions of Ganymede, Europa, Patroclus, and Psyche. Co-I Tracy Becker similarly has experience using STIS, including as PI of programs to observe Europa and Psyche. She is also a rings expert and will apply this experience to the assessment of the inner moon contributions to Jupiter's rings. Co-I Joshua Kammer has extensive experience in spectral data analysis, including HST data. He also works on mapping Jupiter's radiation environment using background count rates detected by Juno-UVS, which we will utilize to investigate the inner moon-magnetosphere interactions. Co-I Kurt Retherford has decades of experience analyzing HST observations of the Galilean moons, particularly Io, and is deputy PI of the JUICE-UVS instrument. He will assist with the identification of Iogenic species on the inner moons. Solar System Astronomy 6 false false false false false false SUPPORTED SOLAR SYSTEM SATELLITE SATELLITE AMALTHEA STD=JUPITER STD=AMALTHEA NOT OCC OF AMALTHEA-LEADING BY JUPITER FROM EARTH, SEP OF AMALTHEA-LEADING IO FROM EARTH GT 25", SEP OF AMALTHEA-LEADING EUROPA FROM EARTH GT 25", SEP OF AMALTHEA-LEADING GANYMEDE FROM EARTH GT 25", SEP OF AMALTHEA-LEADING CALLISTO FROM EARTH GT 25", OLG OF AMALTHEA-LEADING BETWEEN 50 130, SEP OF AMALTHEA-LEADING JUPITER FROM EARTH GT 30" EARTH SOLAR SYSTEM SATELLITE SATELLITE AMALTHEA STD=JUPITER STD=AMALTHEA NOT OCC OF AMALTHEA-TRAILING BY JUPITER FROM EARTH, SEP OF AMALTHEA-TRAILING IO FROM EARTH GT 25", SEP OF AMALTHEA-TRAILING EUROPA FROM EARTH GT 25", SEP OF AMALTHEA-TRAILING GANYMEDE FROM EARTH GT 25", SEP OF AMALTHEA-TRAILING CALLISTO FROM EARTH GT 25", OLG OF AMALTHEA-TRAILING BETWEEN 230 310, SEP OF AMALTHEA-TRAILING JUPITER FROM EARTH GT 30" EARTH SOLAR SYSTEM SATELLITE SATELLITE THEBE STD=JUPITER STD=THEBE NOT OCC OF THEBE-LEADING BY JUPITER FROM EARTH, SEP OF THEBE-LEADING IO FROM EARTH GT 20", SEP OF THEBE-LEADING EUROPA FROM EARTH GT 20", SEP OF THEBE-LEADING GANYMEDE FROM EARTH GT 20", SEP OF THEBE-LEADING CALLISTO FROM EARTH GT 20", OLG OF THEBE-LEADING BETWEEN 75 105, SEP OF THEBE-LEADING JUPITER FROM EARTH GT 30" EARTH SOLAR SYSTEM SATELLITE SATELLITE THEBE STD=JUPITER STD=THEBE NOT OCC OF THEBE-TRAILING BY JUPITER FROM EARTH, SEP OF THEBE-TRAILING IO FROM EARTH GT 30", SEP OF THEBE-TRAILING EUROPA FROM EARTH GT 30", SEP OF THEBE-TRAILING GANYMEDE FROM EARTH GT 30", SEP OF THEBE-TRAILING CALLISTO FROM EARTH GT 30", OLG OF THEBE-TRAILING BETWEEN 255 285, SEP OF THEBE-TRAILING JUPITER FROM EARTH GT 30" EARTH STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 POS-TARG MOSAIC DITHER 0.025 STIS-ALONG-SLIT false true 3 0.0 POS-TARG STIS-PERP-TO-SLIT 90.0 1

false

1765229007819 Using ephemeris for target 17727-01-THEBE-LEADING ephemeris data for target 17727-01-THEBE-LEADING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v01.xml Single orbit visit to observe Thebe's leading hemisphere 1732747090000 268.2726022407343 (Tic-Visit :proposal-id 17727 :visit-id "01" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:27.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 178224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2263 :al-overhead-at-end 0 :internal-dur-at-end 440 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0 1765229008194 Using ephemeris for target 17727-02-THEBE-TRAILING ephemeris data for target 17727-02-THEBE-TRAILING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v02.xml Identical to Visit 1 except the target is Thebe's trailing hemisphere 1731668885000 266.7952800846202 (Tic-Visit :proposal-id 17727 :visit-id "02" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:28.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 178224 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2263 :al-overhead-at-end 0 :internal-dur-at-end 440 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0 1765229009061 Using ephemeris for target 17727-03-AMALTHEA-LEADING ephemeris data for target 17727-03-AMALTHEA-LEADING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v03.xml 2 orbit visit to observe Amalthea's leading hemisphere (Tic-Visit :proposal-id 17727 :visit-id "03" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:28.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 247712 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2265 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17727 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2257 :al-overhead-at-end 0 :internal-dur-at-end 699 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 2 0 Buffer time is 4/5 of the value from the ETC calculation 1765229018388 Using ephemeris for target 17727-3A-AMALTHEA-LEADING ephemeris data for target 17727-3A-AMALTHEA-LEADING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v3A.xml 2 orbit visit to observe Amalthea's leading hemisphere (Tic-Visit :proposal-id 17727 :visit-id "3A" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 156960 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "3A" :obset-id "3A" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "3A" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2487 :al-overhead-at-end 0 :internal-dur-at-end 440 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2867 :pcs-gap 0 ) true 1 0 Buffer time is 4/5 of the value from the ETC calculation 1765229019621 Using ephemeris for target 17727-3B-AMALTHEA-LEADING ephemeris data for target 17727-3B-AMALTHEA-LEADING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v3B.xml 2 orbit visit to observe Amalthea's leading hemisphere (Tic-Visit :proposal-id 17727 :visit-id "3B" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:39.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 91168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "3B" :obset-id "3B" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "3B" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2486 :al-overhead-at-end 0 :internal-dur-at-end 699 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2867 :pcs-gap 0 ) true 1 0 1765229011499 Using ephemeris for target 17727-04-AMALTHEA-TRAILING ephemeris data for target 17727-04-AMALTHEA-TRAILING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v04.xml Identical to visit 3 but targeting Amalthea's trailing hemisphere (Tic-Visit :proposal-id 17727 :visit-id "04" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 247712 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2265 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17727 :visit-id "04" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2257 :al-overhead-at-end 0 :internal-dur-at-end 699 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 2 0 1765229020118 Using ephemeris for target 17727-4A-AMALTHEA-TRAILING ephemeris data for target 17727-4A-AMALTHEA-TRAILING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v4A.xml Identical to visit 3 but targeting Amalthea's trailing hemisphere (Tic-Visit :proposal-id 17727 :visit-id "4A" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:40.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 156960 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "4A" :obset-id "4A" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "4A" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2487 :al-overhead-at-end 0 :internal-dur-at-end 440 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2867 :pcs-gap 0 ) true 1 0 1765229021756 Using ephemeris for target 17727-4B-AMALTHEA-TRAILING ephemeris data for target 17727-4B-AMALTHEA-TRAILING does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 24.289 to 26.335. ephemeris interval: 25.334 to 27.335 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/weck/work/OP-cache/17727-v4B.xml Identical to visit 3 but targeting Amalthea's trailing hemisphere (Tic-Visit :proposal-id 17727 :visit-id "4B" :proposal-version -1 :trans-version "20250929" :date "08-Dec-2025 16:23:41.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 91168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17727 :visit-id "4B" :obset-id "4B" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17727 :visit-id "4B" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2486 :al-overhead-at-end 0 :internal-dur-at-end 699 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2867 :pcs-gap 0 ) true 1 0