6552( 11) - 08/28/96 11:56 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6552 Version: 11 Check-in Date: 28-Aug-1996 12:52:47 1.Proposal Title: Spectrophotometry of Inner Jovian Satellites ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: BENJAMIN ZELLNER GEORGIA SOUTHERN UNIVERSITY CoI: Brian Flynn Southwest Research Institute N CoI: Jonathan Gradie University of Hawaii N CoI: Robert Johnson University of Virginia N CoI: Dan Pascu U. S. Naval Observatory N CoI: Alan Stern Southwest Research Institute N CoI: Peter Thomas Cornell University N CoI: Joseph Veverka Cornell University N CoI: Eddie Wells Computer Sciences Corporation N ------------------------------------------------------------------------------------ 6. Abstract We propose spectrophotometry with the Faint Object Spectrograph of the inner Jovian satellites Amalthea, Thebe, and Metis, which are difficult or impossible to observe from the ground. A paired-aperture technique will be used for accurate measurements of the scattered light from Jupiter. We expect to get good spectra to wavelengths as short as 0.25 microns for Amalthea and Thebe and 0.27 microns for Metis. The results will be interpreted with a combination of astronomical, experimental, and theoretical efforts, including reference to laboratory reflectance spectra for a wide variety of sulfur-bearing compounds and comparison to astronomical data for other dark, red objects in the solar system. We expect to: (1) Determine if Amalthea, Metis and Thebe share similar spectral characteristics; (2) Better determine the leading/trailing spectral asymmetry of Amalthea, Thebe and, if it exists, Metis; (3) Determine if sulfur compounds have been transported inward from Io to these satellites as the leading/trailing asymmetries suggest; (4) Obtain a spectral signature for the bright spot Gaea on Amalthea using spectral demixing; (5) Obtain the observational data needed to direct laboratory experiments on sulfur- silicate micrometeoritic glass production and sulfur ion implantation; and (6) Provide insight into the micrometeorite/contaminate process on airless bodies as a benchmark for understanding space weathering on asteroids and the satellites of Saturn. ------------------------------------------------------------------------------------ Observations Description ------------------------ We have made considerable effort to calculate the amount of scattered light from Jupiter to demonstrate that HST with its smooth optics in space can indeed make the desired observations. We used standard HST reference materials but corrected the calculated scattered intensities by an empirical factor determined from our actual FOS observations of scattered light from Mars for our Cycle 3 program 3744. From those calculations it is evident that Amalthea and Thebe will be easy. Metis will be practicable at the longer wavelengths using the paired-aperture techniques described below, but Adrastea because of its extreme faintness would be quite difficult even for HST. Because of the large amounts of scattered light, high-precision measurements of the sky at the same angular distances as the satellites are necessary. For the Jovian satellites we have chosen to use the 0.5-PAIR aperture of the FOS with the STAR -SKY step pattern. With the target in one aperture, this step pattern alternately takes data from the target aperture and the sky aperture 2.6 arcseconds away, The geometry is such that at nominal spacecraft roll the sky measurements will be taken ''below'' the satellites at very nearly the same radial distance from Jupiter. All observations will be made using the FOS/Red with the Prism in order to obtain the widest range of wavelength coverage with reasonable exposure times. In order to limit each visit to one orbit, a large aperture is desired to minimize the target acquisition time. However, a small aperture is desired to minimize the amount of scattered light. As a compromise, the 0.5-Pair aperture was chosen. For this aperture a 9 minute ACQ/BINARY and 14 minute ACQ/PEAK is required. After the GS acquisition, target acquisitions, and overheads, there remains 4.5-6 minutes for the satellite observation and the same for the sky. For Amalthea and Thebe we can attain a signal-to-noise ratio of 10 and higher per diode over the wavelength range of 2500- 8000 Angstrom. For Metis, the short wavelength limit will be about 2700 Angstrom. To obtain measurements of the leading and trailing sides of the synchronously rotating satellites, we ask for observations near both eastern and western elongations. The resulting spectra for the satellites must be reduced to spectral reflectivities by dividing out the instrumental response for a solar- type star. Thus we also requested observations of a solar-analog comparison star with the same paired apertures. However, this program was allocated only 6 orbits. In another Cycle 6 program (GO-6487) we were allocated two orbits for that purpose. We will use the results from that program in calculating reflectivities. Real Time Justification ----------------------- We require that each satellite be observed near an eastern and a western elongation. Jupiter comes to opposition in early July 1996. Observations within a few weeks of opposition would maximize the count rate and minimize the scattered light from Jupiter This would be a good program for early scheduling in Cycle 6. No supporting observations are required. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: STSCI Ship Via: Email: wells@stsci.edu , ------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 1] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: AMALTHEA-EAST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE AMALTHEA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=AMALTHEA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF AMALTHEA FROM EARTH BETWEEN 70 | 110 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 14.2+/-0.2 | Target is Jovian satellite Amalthea B-V = 1.5+/-0.3 | near greatest Eastern elongation. | Longitude window can be enlarged if | necessary. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: AMALTHEA-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE AMALTHEA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=AMALTHEA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF AMALTHEA FROM EARTH BETWEEN 250 | 290 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 14.2+/-0.2 | Target is Jovian satellite Amalthea B-V = 1.5+/-0.3 | near greatest Western elongation. | Longitude window can be enlarged if | necessary. | ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 2] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: THEBE-EAST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE THEBE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=THEBE | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF THEBE FROM EARTH BETWEEN 75 105 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 15.8+/-0.2 | Target is Jovian satellite Thebe B-V = 1.3+/-0.3 | near greatest Eastern elongation. | Longitude window can be enlarged if | necessary. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: THEBE-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE THEBE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=THEBE | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF THEBE FROM EARTH BETWEEN 255 285 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 15.8+/-0.2 | Target is Jovian satellite Thebe B-V = 1.3+/-0.3 | near greatest Western elongation. | Longitude window can be enlarged if | necessary. | ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 | TARGET NAME: METIS-EAST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE METIS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=METIS | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF METIS FROM EARTH BETWEEN 60 120 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 17.6+/-0.2 | Target is Jovian satellite Metis | near greatest Eastern elongation. | Longitude window can be enlarged if | necessary. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 6 | TARGET NAME: METIS-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE METIS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=METIS | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF METIS FROM EARTH BETWEEN 240 300 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 17.6+/-0.2 | Target is Jovian satellite Metis | near greatest Western elongation. | Longitude window can be enlarged if | necessary. | ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 12 | TARGET NAME: AMALTHEA-WEST-2 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE AMALTHEA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=AMALTHEA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF AMALTHEA FROM EARTH BETWEEN 250 | 290 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 14.2+/-0.2 | Target is Jovian satellite Amalthea B-V = 1.5+/-0.3 | near greatest Western elongation. | Longitude window can be enlarged if | necessary. This is a copy of target | 2 made since a new ephemeris | integration is needed for visit 12 | which is a repeat for failed visit | 2. | ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 5] Visit: 01 Visit Requirements: BETWEEN 06-Jun-1996 AND 20-Aug-1996 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 AMALTHEA-EA FOS/RD ACQ/BIN 4.3 MIRROR 1 3.4 S MIN DUR SEQ 1-3 NON-INT ST ARY ONBOARD ACQ FOR 2 Comments: Onboard acquisition for exposure 2. ------------------------------------------------------------------------------------------------------------------------------------ 2 AMALTHEA-EA FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 0.3 S ONBOARD ACQ FOR 3 ST K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 3. ------------------------------------------------------------------------------------------------------------------------------------ 3 AMALTHEA-EA FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 11.95 M MIN DUR EXPAND ST R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 6] Visit: 02 Visit Requirements: BETWEEN 06-Jun-1996 AND 15-Aug-1996 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 AMALTHEA-WE FOS/RD ACQ/BIN 4.3 MIRROR 1 3.4 S MIN DUR SEQ 4-6 NON-INT ST ARY ONBOARD ACQ FOR 5 Comments: Onboard acquisition for exposure 5. ------------------------------------------------------------------------------------------------------------------------------------ 5 AMALTHEA-WE FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 0.3 S ONBOARD ACQ FOR 6 ST K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 6. ------------------------------------------------------------------------------------------------------------------------------------ 6 AMALTHEA-WE FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 11.95 M MIN DUR EXPAND ST R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 7] Visit: 03 Visit Requirements: BETWEEN 06-Jun-1996 AND 15-Aug-1996 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 7 THEBE-EAST FOS/RD ACQ/BIN 4.3 MIRROR 1 15.0 S MIN DUR SEQ 7-9 NON-INT ARY ONBOARD ACQ FOR 8 Comments: Onboard acquisition for exposure 8. ------------------------------------------------------------------------------------------------------------------------------------ 8 THEBE-EAST FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 1.3 S ONBOARD ACQ FOR 9 K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 9. ------------------------------------------------------------------------------------------------------------------------------------ 9 THEBE-EAST FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 11.5 M MIN DUR EXPAND R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 8] Visit: 04 Visit Requirements: BETWEEN 06-Jun-1996 AND 20-Aug-1996 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 THEBE-WEST FOS/RD ACQ/BIN 4.3 MIRROR 1 15.0 S MIN DUR SEQ 10-12 NON-INT ARY ONBOARD ACQ FOR 11 Comments: Onboard acquisition for exposure 11. ------------------------------------------------------------------------------------------------------------------------------------ 11 THEBE-WEST FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 1.3 S ONBOARD ACQ FOR 12 K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 12. ------------------------------------------------------------------------------------------------------------------------------------ 12 THEBE-WEST FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 11.5 M MIN DUR EXPAND R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 9] Visit: 05 Visit Requirements: BETWEEN 06-Jun-1996 AND 20-Aug-1996 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 13 METIS-EAST FOS/RD ACQ/BIN 4.3 MIRROR 1 79 S MIN DUR SEQ 13-15 NON-INT ARY ONBOARD ACQ FOR 14 Comments: Onboard acquisition for exposure 14. ------------------------------------------------------------------------------------------------------------------------------------ 14 METIS-EAST FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 6.8 S ONBOARD ACQ FOR 15 K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 15. ------------------------------------------------------------------------------------------------------------------------------------ 15 METIS-EAST FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 8.75 M MIN DUR EXPAND R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 10] Visit: 06 Visit Requirements: BETWEEN 06-Jun-1996 AND 15-Aug-1996 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 16 METIS-WEST FOS/RD ACQ/BIN 4.3 MIRROR 1 79 S MIN DUR SEQ 16-18 NON-INT ARY ONBOARD ACQ FOR 17 Comments: Onboard acquisition for exposure 17. ------------------------------------------------------------------------------------------------------------------------------------ 17 METIS-WEST FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 6.8 S ONBOARD ACQ FOR 18 K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 18. ------------------------------------------------------------------------------------------------------------------------------------ 18 METIS-WEST FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 8.75 M MIN DUR EXPAND R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 11] Visit: 12 Visit Requirements: BETWEEN 16-Sep-1996 AND 07-Oct-1996 On Hold Comments: Additional Comments: This is a repeat for visit 2 which failed due to guide star problems. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 AMALTHEA-WE FOS/RD ACQ/BIN 4.3 MIRROR 1 3.4 S MIN DUR SEQ 4-6 NON-INT ST-2 ARY ONBOARD ACQ FOR 5 Comments: Onboard acquisition for exposure 5. ------------------------------------------------------------------------------------------------------------------------------------ 5 AMALTHEA-WE FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 0.3 S ONBOARD ACQ FOR 6 ST-2 K SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 Comments: Onboard acquisition for exposure 6. ------------------------------------------------------------------------------------------------------------------------------------ 6 AMALTHEA-WE FOS/RD ACCUM 0.5-PAI PRISM STEP-PATT=OBJ-SKY 1 11.95 M MIN DUR MAX DUR ST-2 R ------------------------------------------------------------------------------------------------------------------------------------ 6552( 11) - 08/28/96 11:56 - [ 12] Summary Form for Proposal 6552 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=4 SEARCH-SIZE-Y=4 SCAN-STEP-X=0.17 SCAN-STEP-Y=0.17 STEP-PATT=OBJ-SKY ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 06-Jun-1996 AND 20-Aug-1996 MIN DUR SEQ 1-3 NON-INT ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 MIN DUR EXPAND BETWEEN 06-Jun-1996 AND 15-Aug-1996 MIN DUR SEQ 4-6 NON-INT ONBOARD ACQ FOR 5 ONBOARD ACQ FOR 6 MIN DUR SEQ 7-9 NON-INT ONBOARD ACQ FOR 8 ONBOARD ACQ FOR 9 MIN DUR SEQ 10-12 NON-INT ONBOARD ACQ FOR 11 ONBOARD ACQ FOR 12 MIN DUR SEQ 13-15 NON-INT ONBOARD ACQ FOR 14 ONBOARD ACQ FOR 15 MIN DUR SEQ 16-18 NON-INT ONBOARD ACQ FOR 17 ONBOARD ACQ FOR 18 BETWEEN 16-Sep-1996 AND 07-Oct-1996 MIN DUR MAX DUR ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names AMALTHEA-EAST AMALTHEA-WEST THEBE-EAST THEBE-WEST METIS-EAST METIS-WEST AMALTHEA-WEST-2 ------------------------------------------------------------------------------------------------------------------------------------