6733( 8) - 10/16/96 10:17 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6733 Version: 8 Check-in Date: 16-Oct-1996 10:13:32 1.Proposal Title: SPATIALLY-RESOLVED MAPPING OF TITAN'S ATMOSPHERE AT SEVERAL INTERESTING WAVELENGTHS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ELIOT YOUNG NASA AMES RESEARCH CENTER CoI: Caitlin Griffith Northern Arizona University Y CoI: Keith Noll Space Telescope Science Institute N CoI: Chris McKay NASA Ames Research Center N CoI: Tobias Owen University of Hawaii N CoI: Byron Han University of Hawaii N CoI: Andrew Fruchter Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract Titan's atmosphere has been largely inaccessible to study. Methane gas and organic aerosols are the major contributors to the atmosphere's opacity. The linear ramp filters are well- suited to studying the distributions of hazes, methane gas, and methane clouds at several altitudes, particularly between the surface and 80 km. Methane's absorption coefficient varies by three orders of magnitude between the 890 nm absorption band and the 950 nm window. Maps made with narrow filters in this range will isolate photons that have penetrated to very specific depths in Titan's atmosphere. Haze particles have high single scattering albedos in this wavelength regime, so that a significant fraction of incident light filters back up from the surface, albeit after multiple scattering events. We plan to use the ramp filters to derive maps at several levels between 0 and 80 km. Voyager radio occultation experiments indicate that Titan's tropopause is around 40 km - exactly the region that we will sample most heavily. This mapping program will help answer the most fundamental questions regarding Titan's atmosphere. We hope to model the photochemical production of haze. Our program has unprecedented sensitivity to methane clouds, and may illustrate circulation in the lower atmosphere. Low-altitude gas-phase methane abundances could help determine relative surface temperatures, the presence of surface volatiles, and perhaps large-scale relief features. ------------------------------------------------------------------------------------ Observations Description ------------------------ We plan five identical visits of two orbits each. Each visit will image Titan at seven wavelengths using either the PC or, for the four exposures which use the linear ramp filter, the WF2 CCD. The three PC exposures are at 619, 889, and 954 nm, and use the methane quad filters and the F953N filter. The LRF exposures on the WF2 are dithered to improve their spatial resolution. Real Time Justification ----------------------- We have three real time requests: 1. Four of the visits should be separated by roughly four days to image Titan over its 16 day period. 2. A fifth visit should be separated from any of the other four by one day to look for short- term variations. 3. The whole 16-day observing program should take place between August 14 and Oct 14, to facilitate simultaneous groundbased observations. Saturn's opposition is around September 14, 1996. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 1] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: TITAN ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE TITAN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | STD=TITAN | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.74+/-0.02 | | ------------------------------------------------------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 2] Visit: 01 Visit Requirements: BETWEEN 14-Oct-1996 AND 21-Oct-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 TITAN WFPC2 IMAGE FQCH4P1 F953N 9545 1 260 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 20 TITAN WFPC2 IMAGE FQCH4P1 FQCH4N15 6190 2 40 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 30 TITAN WFPC2 IMAGE FQCH4P1 FQCH4P15 8890 1 160 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 40 TITAN WFPC2 IMAGE LRF LRF 9020 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 50 TITAN WFPC2 IMAGE LRF LRF 9150 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 60 TITAN WFPC2 IMAGE LRF LRF 9290 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 70 TITAN WFPC2 IMAGE LRF LRF 9400 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 3] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Please note that the special requirement (AFTER 01 BY 16H TO 30H) is overly restrictive. Our goal is to have this visit occur within 16 to 30 hours of any of the other four visits, NOT NECESSARILY after visit 01. Our PC recommended the AFTER keyword to accomplish this, but this visit could just as easily be scheduled approximately one day before or after any of the other four visits in this proposal. The science goal is to look for short- term variations in Titan's atmosphere (e.g., clouds). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 TITAN WFPC2 IMAGE FQCH4P1 F953N 9545 1 260 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 20 TITAN WFPC2 IMAGE FQCH4P1 FQCH4N15 6190 2 40 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 30 TITAN WFPC2 IMAGE FQCH4P1 FQCH4P15 8890 1 160 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 40 TITAN WFPC2 IMAGE LRF LRF 9020 DITHER-TYPE=LINE 1 30 S ------------------------------------------------------------------------------------------------------------------------------------ 50 TITAN WFPC2 IMAGE LRF LRF 9150 DITHER-TYPE=LINE 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 60 TITAN WFPC2 IMAGE LRF LRF 9290 DITHER-TYPE=LINE 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 70 TITAN WFPC2 IMAGE LRF LRF 9400 DITHER-TYPE=LINE 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 4] Visit: 03 Visit Requirements: AFTER 01 BY 3.5D TO 4.5D 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 TITAN WFPC2 IMAGE FQCH4P1 F953N 9545 1 260 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 20 TITAN WFPC2 IMAGE FQCH4P1 FQCH4N15 6190 2 40 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 30 TITAN WFPC2 IMAGE FQCH4P1 FQCH4P15 8890 1 160 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 40 TITAN WFPC2 IMAGE LRF LRF 9020 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 50 TITAN WFPC2 IMAGE LRF LRF 9150 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 60 TITAN WFPC2 IMAGE LRF LRF 9290 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 70 TITAN WFPC2 IMAGE LRF LRF 9400 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 5] Visit: 04 Visit Requirements: AFTER 01 BY 7.5D TO 8.5D 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 TITAN WFPC2 IMAGE FQCH4P1 F953N 9545 1 260 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 20 TITAN WFPC2 IMAGE FQCH4P1 FQCH4N15 6190 2 40 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 30 TITAN WFPC2 IMAGE FQCH4P1 FQCH4P15 8890 1 160 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 40 TITAN WFPC2 IMAGE LRF LRF 9020 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 50 TITAN WFPC2 IMAGE LRF LRF 9150 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 60 TITAN WFPC2 IMAGE LRF LRF 9290 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 70 TITAN WFPC2 IMAGE LRF LRF 9400 DITHER-TYPE=LINE 1 160 S ------------------------------------------------------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 6] Visit: 05 Visit Requirements: AFTER 01 BY 11.5D TO 12.5D After 02 by 16h to 30h 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 TITAN WFPC2 IMAGE FQCH4P1 F953N 9545 1 260 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 20 TITAN WFPC2 IMAGE FQCH4P1 FQCH4N15 6190 2 40 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 30 TITAN WFPC2 IMAGE FQCH4P1 FQCH4P15 8890 1 160 S 5 ------------------------------------------------------------------------------------------------------------------------------------ 40 TITAN WFPC2 IMAGE LRF LRF 9020 DITHER-TYPE=LINE 1 30 S ------------------------------------------------------------------------------------------------------------------------------------ 50 TITAN WFPC2 IMAGE LRF LRF 9150 DITHER-TYPE=LINE 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 60 TITAN WFPC2 IMAGE LRF LRF 9290 DITHER-TYPE=LINE 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 70 TITAN WFPC2 IMAGE LRF LRF 9400 DITHER-TYPE=LINE 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 6733( 8) - 10/16/96 10:17 - [ 7] Summary Form for Proposal 6733 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=LINE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 14-Oct-1996 AND 21-Oct-1996 AFTER 01 BY 3.5D TO 4.5D AFTER 01 BY 7.5D TO 8.5D AFTER 01 BY 11.5D TO 12.5D After 02 by 16h to 30h ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F953N FQCH4N15 FQCH4P15 LRF ------------------------------------------------------------------------------------------------------------------------------------ Target Names TITAN ------------------------------------------------------------------------------------------------------------------------------------