6760( 26) - 01/20/97 10:23 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6760 Version: 26 Check-in Date: 20-Jan-1997 10:20:13 1.Proposal Title: The second measurement of D/H in Mars' upper atmosphere ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: MICHAEL J. MUMMA NASA GODDARD SPACE FLIGHT CENTER CoI: Vladimir Krasnopolsky National Research Council/Goddard Space Y Flight Center CoI: Randy Gladstone Southwest Research Institute N ------------------------------------------------------------------------------------ 6. Abstract The measured deuterium enrichment in Martian water vapor by a factor of 5.5 relative to the Earth's D/H ratio implies massive loss and fractionation of both isotopes in the planet's history. The current D/H escape ratio is of great importance in understanding of these processes. It can be obtained from high- resolution spectroscopy of the D and H Lyman-alpha lines. A previous attempt to observe these lines was made by Bertaux et al. (1992) using GHRS before Cycle 1 in May 1991 (proposal 2393). It resulted in only an upper limit of 30 R to the D line. We propose to repeat this observation and expect substantial improvements due to (1) anticorrelation of H and D on Mars with solar activity which will provide an increase of the D line intensity by a factor of 2.2, (2) observation on the limb where the D line is stronger by a factor of 3.5 than at disk center, (3) Mars will be in the antisolar hemisphere, and this will reduce the scattered light from the geocoronal H line by an order of magnitude, (4) our measurement of three parameters of the H profile which make possible an accurate determination of the D/H escape ratio. The GHRS in ECH-A with LSA should be used on ten orbits. It is necessary to make this observation in Cycle 6 in January 1997 because the next opposition of Mars will be in May 1999 when solar activity will be moderate and we will lose the important advantage of high H and D densities at solar minimum. Besides, the properties of GHRS are much better for observations of faint extended objects than the expected properties of STIS. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to measure spectra of Mars at the end of January 1997 using the GHRS ECH-A46 mode at 1212-1218 A with LSA at four positions of the LSA center: (1) on the dayside limb (measurement of the D line). The calculated line intensity is 73 R. To be more secure, we adopt 40 R, and signal S = 0.002 counts/diode/sec. Dark count is d = 0.005, and the calculated scattered light adds 0.0014. The total exposure for 7.5 orbits is equal to 7.5x1700 = 13000 sec and results in S/N = 7. (2 and 3) LSA is centered 2" (1400 km) below and 2" above the dayside limb, and the H line is measured. The expected intensity is 3 kR, S = 0.15 counts/diode/sec, and S/N = 20 can be reached for 400 sec. (4) LSA is centered 6"(4200 km) offset the dayside limb. The expected intensity is 1 kR, S = 0.05 counts/diode/sec, and S/N = 20 can be reached in 1200 sec. Approx. one and half orbit is needed for positions (2-4). (5) LSA is 60" (40000 km) offset the Martian limb to measure the terrestrial airglow background which will be subtracted from the measured spectra. This background varies along the orbit, and one full orbit of the total 10 orbits will be given for this measurement. Real Time Justification ----------------------- The next opposition of Mars will be in March 1997, and we request the observations at the period of January 15-31, 1997, just before replacing GHRS by STIS, to get a better angular size of Mars. We plan simultaneous high- resolution spectroscopic observations of Mars in the infrared using our new spectrograph with the IRTF telescope. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: V. A. Krasnopolsky, GSFC Code 693, Greenbelt MD 20771 Ship Via: Email: YS2VK@LEPVAX.GSFC.NASA.GOV , ------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 1] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: MARS-LIMB1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET MARS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=MARS | TYPE=TORUS,LONG=270,LAT=0,RAD=3400,POLE_ | LAT=90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SIZE MARS GT 9 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SIZE=1.74 | LSA of GHRS is centered on Mars' SURF(V) = 5.4+/-0.6 | dayside limb E(B-V) = 1.4+/-0.3 | F-LINE(1215.33)=5+/-3e-13 | W-LINE(1215.33)=0.01+/-0.002 | F-LINE(1215.64)=4.6+/-2e-12 | W-LINE(1215.64)=0.1+/-0.03 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: MARS-DISK ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET MARS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=MARS | TYPE=TORUS,LONG=270,LAT=0,RAD=2000,POLE_ | LAT=90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SIZE MARS GT 9 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SIZE=1.74 | LSA of GHRS is centered 1400 km SURF(V) = 4.6+/-0.6 | below Mars' dayside limb E(B-V) = 1.4+/-0.3 | F-LINE(1215.64)=4.6+/-2e-12 | W-LINE(1215.64)=0.1+/-0.03 | | ------------------------------------------------------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 2] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: MARS-LIMB2 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET MARS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=MARS | TYPE=TORUS,LONG=270,LAT=0,RAD=7600,POLE_ | LAT=90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SIZE MARS GT 9 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SIZE=1.74 | LSA of GHRS is centered 4200 km F-LINE(1215.64)=2.8+/-1e-12 | above Mars' dayside limb. Visual W-LINE(1215.64)=0.1+/-0.03 | magnitude cannot be specified. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: MARS-LIMB3 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET MARS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=MARS | TYPE=TORUS,LONG=270,LAT=0,RAD=4800,POLE_ | LAT=90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SIZE MARS GT 9 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SIZE=1.74 | LSA of GHRS is centered 1400 km F-LINE(1215.64)=4.6+/-2e-12 | above Mars' dayside limb. Visual W-LINE(1215.64)=0.1+/-0.03 | magnitude cannot be specified. | ------------------------------------------------------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 | TARGET NAME: MARS-BGD ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET MARS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=MARS | TYPE=TORUS,LONG=270,LAT=0,RAD=44000,POLE | _LAT=90 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SIZE MARS GT 9 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | F-LINE(1215.67)=4+/-2e-12 | LSA of GHRS is centered approx. W-LINE(1215.67)=0.05+/-0.02 | 40000 km above Mars' dayside limb. SIZE=1.74 | Flux is the terrestrial airglow | background. | ------------------------------------------------------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 4] Visit: 01 Visit Requirements: ORIENT 268D TO 268D BETWEEN 15-Jan-1997 AND 31-Jan-1997 GROUP 01,11 WITHIN 24 H On Hold Comments: Additional Comments: MARS' diameter increasing from 9" on 1/14/97 to 10.5" on 1/31/97. HRS dispersion +X to be directed to Sun as close as possible (the best ORIENT - 45D TO -45D FROM NOMINAL). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 MARS-LIMB1 HRS ACCUM 2.0 ECH-A46 1212-12 19 435.2 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 5] Visit: 11 Visit Requirements: ORIENT 268D TO 268D On Hold Comments: Additional Comments: MARS' diameter increasing from 9" on 1/14/97 to 10.5" on 1/31/97. HRS dispersion +X to be directed to Sun as close as possible (the best ORIENT - 45D TO -45D FROM NOMINAL). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 20 MARS-LIMB1 HRS ACCUM 2.0 ECH-A46 1212-12 17 435.2 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 21 MARS-LIMB1 HRS ACCUM 2.0 ECH-A46 1212-12 1 217.6 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 30 MARS-DISK HRS ACCUM 2.0 ECH-A46 1212-12 1 435.2 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 6] Visit: 02 Visit Requirements: BETWEEN 15-Jan-1997 AND 31-Jan-1997 ORIENT 268D TO 268D 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 ------------------------------------------------------------------------------------------------------------------------------------ 40 MARS-LIMB2 HRS ACCUM 2.0 ECH-A46 1212-12 3 435.2 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 50 MARS-LIMB3 HRS ACCUM 2.0 ECH-A46 1212-12 1 326.4 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 60 MARS-BGD HRS ACCUM 2.0 ECH-A46 1212-12 1 326.4 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 61 MARS-BGD HRS ACCUM 2.0 ECH-A46 1212-12 3 435.2 S 18 ------------------------------------------------------------------------------------------------------------------------------------ 6760( 26) - 01/20/97 10:23 - [ 7] Summary Form for Proposal 6760 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 268D TO 268D BETWEEN 15-Jan-1997 AND 31-Jan-1997 GROUP 01,11 WITHIN 24 H ORIENT 268D TO 268D BETWEEN 15-Jan-1997 AND 31-Jan-1997 ORIENT 268D TO 268D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements ECH-A46 ------------------------------------------------------------------------------------------------------------------------------------ Target Names MARS-LIMB1 MARS-DISK MARS-LIMB2 MARS-LIMB3 MARS-BGD ------------------------------------------------------------------------------------------------------------------------------------