6028( 0) - 07/18/95 19:26 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6028 Version: ********** Check-in Date: ********** 1.Proposal Title: Composition of Surface Units on Io ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Solar System GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: John Spencer Lowell Observatory CoI: Melissa McGrath Space Telescope Science Institute Y CoI: Alfred McEwen USGS Flagstaff N CoI: Paola Sartoretti Space Telescope Science Insititute N CoI: John Clarke University of Michigan N CoI: John Trauger Jet Propulsion Laboratory N CoI: Gilda Ballester University of Michigan N ------------------------------------------------------------------------------------ 6. Abstract Io's surface composition is still poorly understood: SO_2 is the only definitively identified component. We plan to obtain a global multispectral map of Io in 12 mostly narrowband filters from 0.22 to 0.79 microns, to obtain the most detailed picture yet of the composition and spatial distribution of its many surface units. The many wavelengths will allow much better determination of unit spectra than previous broadband imaging, which should lead to more definitive compositional identifications. We are particularly interested in the composition of the polar regions, and the spectrally unusual deposits of the Pele volcano, first noted in our Cycle 4 HST images of Io, which may be rich in S_2O or Na_2S. ------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 2] Observations Description ------------------------ We will image four longitudes on Io (c. 70, 160, 250, and 340 degrees), giving complete surface coverage, in twelve filters, at 0.218, 0.255, 0.343, 0.374, 0.409, 0.467, 0.501, 0.548, 0.589, 0.659, and 0.779 microns (an exception is that we will only use the 0.218 and 0.255 micron filters at 160 and 340 degrees longitude). Exposure times range from 1000 seconds (F343N) to 0.3 seconds (F791W): we have determined them from exposures used successfully for Cycle 4 Io observations with WFPC, scaled for the relative sensitivity of the filters (from the WFPC2 Handbook) and the wavelength dependence of the flux from Io. Like the Cycle 4 images, these exposures will yield about 30,000 electrons per pixel on Io, giving a S/N of 170, more than adequate for distinguishing candidate materials on Io. S/N in the 0.218 micron filter will be lower, as we will be restricted to 500 second integrations to keep within our orbit limit, but 1000- second images taken in Cycle 4 by Clarke et al. have adequate S/N and ours will only be lower by sqrt2. We can image each Io longitude through all these filters in two HST orbits. Real Time Justification ----------------------- The observations are time-critical in that we require Io to be within +/- 15 degrees of the requested orbital longitude in order to obtain global coverage. As described in the justification, we will take CCD spectra of Io from the Lowell Observatory 72'' telescope at the same orbital and solar phases as the HST observations, for spectrophotometric calibration. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: IO-LON70 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=IO | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IO BETWEEN 60 80 RANGE EARTH | JUPITER LT 4.7 SEP OF JUPITER IO FROM | EARTH GT 5.0" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V)=5.14 B-V = 1.2 | Io should less than 4.7 AU from | Earth for maximum resolution, and | more than 5 arcsec from Jupiter's | limb to avoid Jupiter scattered | light | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: IO-LON160 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=IO | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IO BETWEEN 140 180 RANGE EARTH | JUPITER LT 4.7 SEP OF JUPITER IO FROM | EARTH GT 5.0" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V)=5.14 B-V = 1.2 | Io should less than 4.7 AU from | Earth for maximum resolution, and | more than 5 arcsec from Jupiter's | limb to avoid Jupiter scattered | light | ------------------------------------------------------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: IO-LON250 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=IO | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IO BETWEEN 235 265 RANGE EARTH | JUPITER LT 4.7 SEP OF JUPITER IO FROM | EARTH GT 5.0" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V)=5.14 B-V = 1.2 | Io should less than 4.7 AU from | Earth for maximum resolution, and | more than 5 arcsec from Jupiter's | limb to avoid Jupiter scattered | light | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: IO-LON340 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=IO | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IO BETWEEN 325 355 RANGE EARTH | JUPITER LT 4.7 SEP OF JUPITER IO FROM | EARTH GT 5.0" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V)=5.14 B-V = 1.2 | Io should be in full sunlight (not | in Jupiter's shadow umbra or | penumbra) for all exposures. Io | should less than 4.7 AU from Earth | for maximum resolution, and more | than 5 arcsec from Jupiter's limb to | avoid Jupiter scattered light | ------------------------------------------------------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 5] Visit: 01 Visit Requirements: 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 IO-LON70 WFPC2 IMAGE PC1 F343N CR-SPLIT=DEF 1 1200S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 2 IO-LON70 WFPC2 IMAGE PC1 F390N ATD-GAIN=15 1 70S ------------------------------------------------------------------------------------------------------------------------------------ 3 IO-LON70 WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 4 IO-LON70 WFPC2 IMAGE PC1 F467M ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 5 IO-LON70 WFPC2 IMAGE PC1 F791W ATD-GAIN=15 1 0.23S ------------------------------------------------------------------------------------------------------------------------------------ 6 IO-LON70 WFPC2 IMAGE PC1 F375N ATD-GAIN=15 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 7 IO-LON70 WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 16S ------------------------------------------------------------------------------------------------------------------------------------ 8 IO-LON70 WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 0.4S ------------------------------------------------------------------------------------------------------------------------------------ 9 IO-LON70 WFPC2 IMAGE PC1 F588N ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 10 IO-LON70 WFPC2 IMAGE PC1 F658N ATD-GAIN=15 1 6S ------------------------------------------------------------------------------------------------------------------------------------ 11 IO-LON70 WFPC2 IMAGE PC1 F255W 1 600S ------------------------------------------------------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 6] Visit: 02 Visit Requirements: 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 IO-LON160 WFPC2 IMAGE PC1 F343N CR-SPLIT=DEF 1 1200S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 2 IO-LON160 WFPC2 IMAGE PC1 F390N ATD-GAIN=15 1 70S ------------------------------------------------------------------------------------------------------------------------------------ 3 IO-LON160 WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 4 IO-LON160 WFPC2 IMAGE PC1 F467M ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 5 IO-LON160 WFPC2 IMAGE PC1 F791W ATD-GAIN=15 1 0.23S ------------------------------------------------------------------------------------------------------------------------------------ 6 IO-LON160 WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 16S ------------------------------------------------------------------------------------------------------------------------------------ 7 IO-LON160 WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 0.4S ------------------------------------------------------------------------------------------------------------------------------------ 8 IO-LON160 WFPC2 IMAGE PC1 F375N ATD-GAIN=15 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 9 IO-LON160 WFPC2 IMAGE PC1 F588N ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 10 IO-LON160 WFPC2 IMAGE PC1 F658N ATD-GAIN=15 1 6S ------------------------------------------------------------------------------------------------------------------------------------ 11 IO-LON160 WFPC2 IMAGE PC1 F255W 1 600S ------------------------------------------------------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 7] Visit: 03 Visit Requirements: 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 IO-LON250 WFPC2 IMAGE PC1 F343N CR-SPLIT=DEF 1 1200S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 2 IO-LON250 WFPC2 IMAGE PC1 F390N ATD-GAIN=15 1 70S ------------------------------------------------------------------------------------------------------------------------------------ 3 IO-LON250 WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 4 IO-LON250 WFPC2 IMAGE PC1 F467M ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 5 IO-LON250 WFPC2 IMAGE PC1 F791W ATD-GAIN=15 1 0.23S ------------------------------------------------------------------------------------------------------------------------------------ 6 IO-LON250 WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 16S ------------------------------------------------------------------------------------------------------------------------------------ 7 IO-LON250 WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 0.4S ------------------------------------------------------------------------------------------------------------------------------------ 8 IO-LON250 WFPC2 IMAGE PC1 F375N ATD-GAIN=15 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 9 IO-LON250 WFPC2 IMAGE PC1 F588N ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 10 IO-LON250 WFPC2 IMAGE PC1 F658N ATD-GAIN=15 1 6S ------------------------------------------------------------------------------------------------------------------------------------ 11 IO-LON250 WFPC2 IMAGE PC1 F255W 1 600S ------------------------------------------------------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 8] Visit: 04 Visit Requirements: 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 IO-LON340 WFPC2 IMAGE PC1 F343N CR-SPLIT=DEF 1 1200S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 2 IO-LON340 WFPC2 IMAGE PC1 F390N ATD-GAIN=15 1 70S ------------------------------------------------------------------------------------------------------------------------------------ 3 IO-LON340 WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 4 IO-LON340 WFPC2 IMAGE PC1 F467M ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 5 IO-LON340 WFPC2 IMAGE PC1 F791W ATD-GAIN=15 1 0.23S ------------------------------------------------------------------------------------------------------------------------------------ 6 IO-LON340 WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 16S ------------------------------------------------------------------------------------------------------------------------------------ 7 IO-LON340 WFPC2 IMAGE PC1 F547M ATD-GAIN=15 1 0.4S ------------------------------------------------------------------------------------------------------------------------------------ 8 IO-LON340 WFPC2 IMAGE PC1 F375N ATD-GAIN=15 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 9 IO-LON340 WFPC2 IMAGE PC1 F588N ATD-GAIN=15 1 3S ------------------------------------------------------------------------------------------------------------------------------------ 10 IO-LON340 WFPC2 IMAGE PC1 F658N ATD-GAIN=15 1 6S ------------------------------------------------------------------------------------------------------------------------------------ 11 IO-LON340 WFPC2 IMAGE PC1 F255W 1 600S ------------------------------------------------------------------------------------------------------------------------------------ 6028( 0) - 07/18/95 19:26 - [ 9] Summary Form for Proposal 6028 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=DEF ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Solar System ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F343N F390N F410M F467M F791W F375N F502N F547M F588N F658N F255W ------------------------------------------------------------------------------------------------------------------------------------ Target Names IO-LON70 IO-LON160 IO-LON250 IO-LON340 ------------------------------------------------------------------------------------------------------------------------------------