5452( 12) - 09/21/95 15:29 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5452 Version: 12 Check-in Date: ********** 1.Proposal Title: COMPOSITION OF DARK MATERIAL ON IAPETUS CYCLE4 - MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM,SATELLIT GO 4 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: NOLL, KEITH STSCI CoI: Pendleton, Yvonne DR. 2852 N CoI: Roush, Theodore DR. 1630 N CoI: Cruikshank, Dale DR. 2852 N ------------------------------------------------------------------------------------ 6. Abstract The chemical identity of dark material in the solar system, both on planetary surfaces and in clouds is a longstanding question. Hypotheses have focussed on organic material produced either in situ, or transported from other bodies through impacts. The laboratory experiments of Khare, Sagan and others have identified a class of complex hydrocarbons that appear to have some of the characteristics appropriate to at least some of the dark matter observed in the solar system. We propose to further the study of organic matter in the solar system by recording the first UV spectra of Iapetus at wavelengths from 1800 to 2600 A, and vastly improve on the S/N of spectra from 2600 to 3300 A. Reflection spectra produced from optical constants of at least one candidate organic material, tholins show structure over this portion of the spectrum that may be identifiable in the dark hemisphere spectrum and help identify the chemical composition of this compared to the presumably ice-dominated bright hemisphere of Iapetus and a control spectrum of another icy Saturn satellite, Rhea. ------------------------------------------------------------------------------------ Observations Description ------------------------ Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 2] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: IAPETUS-DARK ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IAPETUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | STD = IAPETUS | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IAPETUS BETWEEN 88 92 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 11.1 +/- 1.2 | DARK HEMISPHERE OF IAPETUS, MUST F-CONT(2200.0) = 19.0 +/- 5.0 E-17 | MAINTAIN NARROW WINDOW F-CONT(1800.0) = 17.0 +/- 5.0 E-18 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: IAPETUS-BRIGHT ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IAPETUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | STD = IAPETUS | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IAPETUS BETWEEN 265 275 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 11.1 +/- 1.2 | BRIGHT HEMISPHERE OF IAPETUS WINDOW F-CONT(2200.0) = 14.0 +/- 5.0 E-16 | IS LESS TIGHT F-CONT(1800.0) = 12.0 +/- 5.0 E-17 | | ------------------------------------------------------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: RHEA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE RHEA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | STD = RHEA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SEP OF SATURN RHEA FROM EARTH GT 30" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 9.7 +/- 0.3 | RHEA MAY BE OBSERVED AT ANY OLG F-CONT(2200.0) = 14.0 +/- 5.0 E-16 | F-CONT(1800.0) = 13.0 +/- 5.0 E-17 | | ------------------------------------------------------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 IAPETUS- FOS/RD ACQ/BIN 4.3 MIRROR 5500.0 1 0.75S ONBOARD ACQ FOR 20-30 DARK ARY ------------------------------------------------------------------------------------------------------------------------------------ 20 IAPETUS- FOS/RD ACCUM 1.0 G270H 2750.0 1 1400S DARK ------------------------------------------------------------------------------------------------------------------------------------ 30 IAPETUS- FOS/RD ACCUM 1.0 G190H 2000.0 1 5500S DARK ------------------------------------------------------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 IAPETUS- FOS/RD IMAGE 4.3 G270H 2600.0 SUB-STEP=4, 1 300S RT ANALYSIS FOR 20-30 BRIGHT COMB=YES, Y- SPACE=128, Y- SIZE=5 Comments: FIVE FOS SPECTRA AT DIFFERENT Y DEFLECTIONS WILL BE OBTAINED FOR TARGET ACQUISITION INFORMATION. ------------------------------------------------------------------------------------------------------------------------------------ 20 IAPETUS- FOS/RD ACCUM 1.0 G270H 2750.0 1 190S REQ UPLINK BRIGHT ------------------------------------------------------------------------------------------------------------------------------------ 30 IAPETUS- FOS/RD ACCUM 1.0 G190H 2000.0 1 540S BRIGHT ------------------------------------------------------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 RHEA FOS/RD IMAGE 4.3 G270H 2600.0 SUB-STEP=4, 1 300S RT ANALYSIS FOR 20-30 COMB=YES, Y- SPACE=128, Y- SIZE=5 Comments: FIVE FOS SPECTRA AT DIFFERENT Y DEFLECTIONS WILL BE OBTAINED FOR TARGET ACQUISITION INFORMATION. ------------------------------------------------------------------------------------------------------------------------------------ 20 RHEA FOS/RD ACCUM 1.0 G270H 2750.0 1 190S REQ UPLINK ------------------------------------------------------------------------------------------------------------------------------------ 30 RHEA FOS/RD ACCUM 1.0 G190H 2000.0 1 540S ------------------------------------------------------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 IAPETUS- FOS/RD ACQ/BIN 4.3 MIRROR 1 0.75S ONBOARD ACQ FOR 20-30 DARK ARY ------------------------------------------------------------------------------------------------------------------------------------ 20 IAPETUS- FOS/RD ACCUM 1.0 G270H 2750.0 1 1400S DARK ------------------------------------------------------------------------------------------------------------------------------------ 30 IAPETUS- FOS/RD ACCUM 1.0 G190H 2000.0 1 5500S DARK ------------------------------------------------------------------------------------------------------------------------------------ 5452( 12) - 09/21/95 15:29 - [ 9] Summary Form for Proposal 5452 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SUB-STEP=4 COMB=YES Y-SPACE=128 Y-SIZE=5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM,SATELLITES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20-30 RT ANALYSIS FOR 20-30 REQ UPLINK ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H G190H ------------------------------------------------------------------------------------------------------------------------------------ Target Names IAPETUS-DARK IAPETUS-BRIGHT RHEA ------------------------------------------------------------------------------------------------------------------------------------