! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /data/frodo1/aroman/work/6760.prop ! Generated by PREPROCESSOR, version 7.0 ! Date: Mon Dec 23 19:29:46 EST 1996 Proposal_Information Title: The second measurement of D/H in Mars' upper atmosphere Proposal_Category: GO Scientific_Category: SOLAR SYSTEM Cycle: 6 Investigators PI_Name: Michael Mumma PI_Institution: Goddard Space Flight Center CoI_Name: Vladimir Krasnopolsky CoI_Institution: National Research Council/Goddard Space Flight Center Contact: Y CoI_Name: Randy Gladstone CoI_Institution: Southwest Research Institute Contact: N 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. Questions Observing_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: Fixed_Targets Solar_System_Targets Target_Number: 1 Target_Name: MARS-LIMB1 Description: PLANET MARS Level_1: STD=MARS Level_2: TYPE=TORUS,LONG=270,LAT=0,RAD=3400,POLE_LAT=90 Level_3: Window: SIZE MARS GT 9 Flux: SIZE=1.74 SURF(V) = 5.4+/-0.6 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 Comments: LSA of GHRS is centered on Mars' dayside limb Target_Number: 2 Target_Name: MARS-DISK Description: PLANET MARS Level_1: STD=MARS Level_2: TYPE=TORUS,LONG=270,LAT=0,RAD=2000,POLE_LAT=90 Level_3: Window: SIZE MARS GT 9 Flux: SIZE=1.74 SURF(V) = 4.6+/-0.6 E(B-V) = 1.4+/-0.3 F-LINE(1215.64)=4.6+/-2e-12 W-LINE(1215.64)=0.1+/-0.03 Comments: LSA of GHRS is centered 1400 km below Mars' dayside limb Target_Number: 3 Target_Name: MARS-LIMB2 Description: PLANET MARS Level_1: STD=MARS Level_2: TYPE=TORUS,LONG=270,LAT=0,RAD=7600,POLE_LAT=90 Level_3: Window: SIZE MARS GT 9 Flux: SIZE=1.74 F-LINE(1215.64)=2.8+/-1e-12 W-LINE(1215.64)=0.1+/-0.03 Comments: LSA of GHRS is centered 4200 km above Mars' dayside limb. Visual magnitude cannot be specified. Target_Number: 4 Target_Name: MARS-LIMB3 Description: PLANET MARS Level_1: STD=MARS Level_2: TYPE=TORUS,LONG=270,LAT=0,RAD=4800,POLE_LAT=90 Level_3: Window: SIZE MARS GT 9 Flux: SIZE=1.74 F-LINE(1215.64)=4.6+/-2e-12 W-LINE(1215.64)=0.1+/-0.03 Comments: LSA of GHRS is centered 1400 km above Mars' dayside limb. Visual magnitude cannot be specified. Target_Number: 5 Target_Name: MARS-BGD Description: PLANET MARS Level_1: STD=MARS Level_2: TYPE=TORUS,LONG=270,LAT=0,RAD=44000,POLE_LAT=90 Level_3: Window: SIZE MARS GT 9 Flux: F-LINE(1215.67)=4+/-2e-12 W-LINE(1215.67)=0.05+/-0.02 SIZE=1.74 Comments: LSA of GHRS is centered approx. 40000 km above Mars' dayside limb. Flux is the terrestrial airglow background. Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: ORIENT 268D TO 268D BETWEEN 15-Jan-1997 AND 31-Jan-1997 GROUP 01,11 WITHIN 24 H On_Hold_Comments: Visit_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). Exposure_Number: 10 Target_Name: MARS-LIMB1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 19 Time_Per_Exposure: 435.2 S Special_Requirements: Comments: Visit_Number: 11 Visit_Requirements: ORIENT 268D TO 268D On_Hold_Comments: Visit_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). Exposure_Number: 20 Target_Name: MARS-LIMB1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 17 Time_Per_Exposure: 435.2 S Special_Requirements: Comments: Exposure_Number: 21 Target_Name: MARS-LIMB1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 217.6 S Special_Requirements: Comments: Exposure_Number: 30 Target_Name: MARS-DISK Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 435.2 S Special_Requirements: Comments: Visit_Number: 02 Visit_Requirements: BETWEEN 15-Jan-1997 AND 31-Jan-1997 ORIENT 268D TO 268D On_Hold_Comments: Visit_Comments: Exposure_Number: 40 Target_Name: MARS-LIMB2 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 3 Time_Per_Exposure: 435.2 S Special_Requirements: Comments: Exposure_Number: 50 Target_Name: MARS-LIMB3 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 326.4 S Special_Requirements: Comments: Exposure_Number: 60 Target_Name: MARS-BGD Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 326.4 S Special_Requirements: Comments: Exposure_Number: 61 Target_Name: MARS-BGD Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A46 Wavelength: 1212-1218 Optional_Parameters: Number_of_Iterations: 3 Time_Per_Exposure: 435.2 S Special_Requirements: Comments: Data_Distribution ! Defaults indicated; change if desired Medium: 8MM Ship_To: V. A. Krasnopolsky, GSFC Code 693, Greenbelt MD 20771 Recipient_Email: YS2VK@LEPVAX.GSFC.NASA.GOV ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator