6758( 26) - 06/13/96 11:57 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6758 Version: 26 Check-in Date: 13-Jun-1996 11:52:17 1.Proposal Title: Far-UV Airglow and Albedo Observations of Europa and Ganymede ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Doyle Hall THE JOHNS HOPKINS UNIVERSITY CoI: Paul Feldman The Johns Hopkins University Y CoI: Melissa McGrath The Space Telescope Science Institute N CoI: Darrell Strobel The Johns Hopkins University N ------------------------------------------------------------------------------------ 6. Abstract The recent HST discovery of a molecular oxygen atmosphere on Europa and the ground- based discovery of oxygen molecules trapped in the near-surface material of Ganymede provide a striking confirmation of the prediction that O_2 is a stable end-product of the evolution icy surfaces exposed to charged-particle radiation. However, questions remain about the nature of the mechanisms that produce the oxygen molecules and excite the observed far-UV emissions. We propose to use the HST GHRS to measure Europa's OI 1304 Angstrom and 1356 Angstrom brightnesses on both leading and trailing hemispheres to establish the long-term stability of the airglow emission, and to determine the magnitude of its leading/trailing hemisphere emission asymmetry. In addition, we propose to search for the same far-UV oxygen emissions on Ganymede, to determine (or place upper limits) on its abundance of gaseous oxygen in both molecular and atomic form. The proposed observations will also provide measurements of Europa's leading and trailing hemisphere geometric albedos, and Ganymede's trailing hemisphere albedo, by using the reflected brightness of the solar CII 1335 Angstrom feature, and will establish the existence of any systematic differences in the abundance of UV-darkening contaminants on the icy surfaces of the satellites. ------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 2] Observations Description ------------------------ We propose three separate observations with the GHRS, all in ACCUM mode using the G140L grating (observing the 1200-1490 Angstrom wavelength interval) with the Large Science Aperture centered on the disk of each satellite. The HST GHRS is uniquely well-suited for this study because of its sensitivity in the far-UV bandpass, and because both satellites fit remarkably well in the Large Science Aperture. Europa is the target of the first two observations, and Ganymede is the third. Each observation requires 5 HST orbits of exposure, designed to provide a measurement of similar statistical quality as obtained by Hall et al. (1995a), who observed Europa's trailing hemisphere during the DARKTIME segments of 6 HST orbits. (However, during one of the these six orbital exposures Europa drifted significantly relative to the LSA boresight, excluding at least a part of the satellite's disk from the aperture, and the combined spectrum, 7290 sec total duration, has the statistical quality of about five correctly-executed HST orbits of exposure.) The measured brightnesses of the brightest and weakest features in the accumulated Hall et al. (1995a) spectrum were I(1356 Angstrom) = 77 +/- 13 and I(1335 Angstrom) = 30 +/- 11 Rayleighs respectively, indicating a 1-Sigma detection threshold of 10--15 Rayleighs, consistent with the signal- to-noise predicted using the formulae and sensitivities given in the GHRS handbook for a source the size of Europa's disk. Thus, the proposed observations will be able to detect ~ 30 Rayleigh emission feature signals the 2--3,Sigma confidence level on Europa. Because the angular size of Ganymede's disk is larger than Europa's, the same on-disk brightness will produce larger GHRS signal levels, and the 1,Sigma detection threshold for Ganymede will be approximately 30% smaller than for Europa (i.e., 7--10 Rayleighs). DARKTIME is preferred for the proposed observations, because OI 1304 Angstrom terrestrial airglow emissions are bright enough during non-DARKTIME periods to contaminate the GHRS spectra. However, we will acquire the data using short (~ 5 minute) individual exposures that are summed afterwards, so that data obtained during non-DARKTIME segments of orbits can still be used to increase the signal-to- noise ratios in wavelength regions not affected by Earth airglow. The first exposure, obtained when Europa is near western elongation with its trailing hemisphere facing the Earth, will be a close reproduction of the Hall et al. (1995a) observation, and is required to confirm the persistence of the oxygen airglow features originally detected by Hall et al. (1995a) and establish a baseline for comparison with the leading hemisphere observation. The second Europa observation will be acquired approximately 43 hours after the first, allowing Europa to move along its orbit from western elongation to eastern elongation. Even though the order of these two observations can be reversed for scheduling purposes if necessary, we request that both be performed within one Europa orbit because this minimizes the chance that the measurements will be adversely affected by Io torus temporal fluctuations. Europa has a diameter of ~ 3140 km and is typically 4.5 AU from the Earth during HST observations, projecting a disk about 0.95 arcsec in diameter that fits nicely inside the 1.74 arcsec square LSA. These two Europa exposures will allow the direct comparison of the leading/trailing hemisphere oxygen airglow brightnesses and far-UV geometric albedos measured in as short a period as possible. The third exposure targets Ganymede near western elongation. At a distance of 4.5 AU, Ganymede's 5260 km solid surface projects a disk about 1.61 arcsec in diameter, also nicely compatible with the size of the GHRS LSA. The goals of this observation are to measure the surface albedo at 1335 Angstrom and search for OI emissions at 1304 and 1356 Angstrom. , Bagenal, F. (1994) JGR 99 11043. Broadfoot, A. L., et al. (1979) Science 204 979. Calvin, W. M. & Spencer, J. R. (1994) Bull. Am. Astr. Soc. 26 1159. Carlson, R. W., et al. (1973) Science 182 53. Cheng, A. F. (1986) in Satellites pp. 403, Univ. of Ariz. Press, Tucson. Clark, R. N. (1980) Icarus 44 388. Eviatar, A., et al. (1981) Icarus 47 75. Eviatar, A., et al. (1985) Icarus 61 185. Hall, D. T., et al. (1995a) Nature 373 677. Hall, D. T., et al. (1995b) Division for Planetary Sci. AAS Abstract. Hapke, B., et al. (1981) Icarus 47 361. Ip, W.-H. (1995) Icarus 115 295. Johnson, R. E. (1990) Energetic Charged-Particle Interactions with Atmosphere and Surfaces, Springer Verlag, Berlin Heidelberg. Kumar, S. and Hunten, D. M. (1982) in Satellites pp. 782, Univ. of Ariz. Press, Tucson, Ariz. Lane, A. L. et al., (1981) Nature 292 38. Morrison, D. (1977) in Planetary Satellites pp.269, Univ. of Ariz. Press, Tucson, Ariz. Nelson, R. M., et al. (1987) Icarus 72 358. Noll, K. et al. (1995) Science, to be submitted. Pospieszalska, M. K. & Johnson, R. E. (1991) Icarus 93 45. Sack, N. J., et al. (1992) Icarus 100 534. Yung, Y. L. & McElroy, M. B. (1977) Icarus 30 97. Real Time Justification ----------------------- Because these observations target the leading and trailing hemispheres of Europa and Ganymede, they require that each satellite be observed within specific orbital longitude windows, as can be requested using an established Solar System Target mode. We request that the trailing and leading hemisphere observations of Europa be performed within one Europa orbit in order to minimize adverse temporal variability effects. Finally, orbital DARKTIME is preferred for all of these observations to minimize terrestrial oxygen airglow contamination. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: , ------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: EUROPA-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=EUROPA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF EUROPA BETWEEN 250 290 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 5.29 | Europa at elongation on Jupiter's B-V = 0.87 | dusk side. The other galilean | satellites must be separated by more | than 10 arcsec from the target (by | default). | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: EUROPA-EAST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=EUROPA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF EUROPA BETWEEN 70 110 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 5.29 | Europa at elongation on Jupiter's B-V = 0.87 | dawn side. The other galilean | satellites must be separated by more | than 10 arcsec from the target (by | default). | ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 5] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: GANYMEDE-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=GANYMEDE | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF GANYMEDE BETWEEN 250 290 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 4.61 | Ganymede at elongation on Jupiter's B-V = 0.83 | dusk side. The other galilean | satellites must be separated by more | than 10 arcsec from the target (by | default). | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: EUROPA-WEST-2 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=EUROPA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF EUROPA BETWEEN 180 360 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 5.29 | B-V = 0.87 | | ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 6] Visit: 01 Visit Requirements: BETWEEN 21-Jun-1996 AND 01-Aug-1996 after 02 by 0d to 12d On Hold Comments: Additional Comments: Schedule the observations in a time period bracketing Jupiter opposition (7 -Jun-96). This ensures that the duration of each orbit's SHADOW interval is near its maximum for Cycle 6 Jupiter observations. The G140L ACCUM mode spectra following acquisition will be short exposures (5M) providing an internal monitor of Earth airglow throughout each orbit, and allowing data from the SHADOW regions to be binned separately. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 111 EUROPA-WEST HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,LOCATE=EXTENDED, 1 5.0 S ONBOARD ACQ FOR 112-114, SEARCH-SIZE=5 121-124,131-134,141-144, 151-154 Comments: An acquisition with STEP-TIME=0.2S using the GHRS Side-2. ------------------------------------------------------------------------------------------------------------------------------------ 112 EUROPA-WEST HRS IMAGE 2.0 MIRROR-N2 1 51.2 S Comments: Image the target to verify pointing accuracy. ------------------------------------------------------------------------------------------------------------------------------------ 113 EUROPA-WEST HRS ACCUM 2.0 G270M 2400. 1 81.6 S ------------------------------------------------------------------------------------------------------------------------------------ 114 EUROPA-WEST HRS ACCUM 2.0 G200M 2000. 1 788.8 S Comments: Use remainder of first orbit for Side-2 measurements of the target UV spectral reflectivity. This time can't be used for Side-1 spectra because of the 40M overhead required to switch to side-1. ------------------------------------------------------------------------------------------------------------------------------------ 121 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 122 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 123 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 124 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 121-124 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 131 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 132 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 133 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 134 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 131-134 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 141 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 142 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 143 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 144 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 141-144 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 151 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 152 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 153 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 154 EUROPA-WEST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 151-154 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 8] Visit: 02 Visit Requirements: BETWEEN 21-Jun-1996 AND 01-Aug-1996 ORIENT 90D TO 90D On Hold Comments: Additional Comments: Schedule the second observation (visit 01) during the next elongation, ensuring that the WEST and EAST are observed in the same Europa orbit. Note that Visit 1 may be executed first for scheduling purposes, but in that case Visit 2 must follow by 40 to 45H. Short G140L exposures provide an monitor of Earth airglow throughout each orbit. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 211 EUROPA-EAST HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,LOCATE=EXTENDED, 1 5.0 S ONBOARD ACQ FOR 212-254 SEARCH-SIZE=5 Comments: An acquisition with STEP-TIME=0.2S using the GHRS Side-2. ------------------------------------------------------------------------------------------------------------------------------------ 212 EUROPA-EAST HRS IMAGE 2.0 MIRROR-N2 1 51.2 S Comments: Image the target to verify pointing accuracy. ------------------------------------------------------------------------------------------------------------------------------------ 213 EUROPA-EAST HRS ACCUM 2.0 G270M 2400. 1 81.6 S ------------------------------------------------------------------------------------------------------------------------------------ 214 EUROPA-EAST HRS ACCUM 2.0 G200M 2000. 1 516.8 S Comments: Use remainder of first orbit for Side-2 measurements of the target UV spectral reflectivity. This time can't be used for Side-1 spectra because of the 40M overhead required to switch to side-1. ------------------------------------------------------------------------------------------------------------------------------------ 221 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 222 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 223 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 224 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 221-224 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 231 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 232 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 233 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 234 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 231-234 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 241 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 242 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 243 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 244 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S Comments: Exposures 241-244 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 251 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 252 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 253 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 254 EUROPA-EAST HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 10] Visit: 03 Visit Requirements: BETWEEN 21-Jun-1996 AND 01-Aug-1996 On Hold Comments: Additional Comments: Schedule the observations in a time period bracketing Jupiter opposition (7 -Jun-96). This ensures that the duration of each orbit's SHADOW interval is near its maximum for Cycle 6 Jupiter observations. The G140L ACCUM mode spectra following acquisition will be short exposures (5M) providing an internal monitor of Earth airglow throughout each orbit, and allowing data from the SHADOW regions to be binned separately. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 311 EUROPA-WEST HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,LOCATE=EXTENDED, 1 5.0 S ONBOARD ACQ FOR 312-354 -2 SEARCH-SIZE=5 Comments: An acquisition with STEP-TIME=0.2S using the GHRS Side-2. ------------------------------------------------------------------------------------------------------------------------------------ 312 GANYMEDE-WE HRS IMAGE 2.0 MIRROR-N2 1 51.2 S ST Comments: Image the target to verify pointing accuracy. ------------------------------------------------------------------------------------------------------------------------------------ 313 GANYMEDE-WE HRS ACCUM 2.0 G270M 2400. 1 81.6 S ST ------------------------------------------------------------------------------------------------------------------------------------ 314 GANYMEDE-WE HRS ACCUM 2.0 G200M 2000. 1 788.8 S ST Comments: Use remainder of first orbit for Side-2 measurements of the target UV spectral reflectivity. This time can't be used for Side-1 spectra because of the 40M overhead required to switch to side-1. ------------------------------------------------------------------------------------------------------------------------------------ 321 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 322 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 323 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 324 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST Comments: Exposures 321-324 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 331 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 11] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 332 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 333 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 334 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST Comments: Exposures 331-334 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 341 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 342 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 343 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 344 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST Comments: Exposures 341-344 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 351 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 352 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 353 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST ------------------------------------------------------------------------------------------------------------------------------------ 354 GANYMEDE-WE HRS ACCUM 2.0 G140L 1356 FP-SPLIT=NO,STEP-PATT=5 1 462.4 S ST Comments: Exposures 351-354 are G140L ACCUM spectra that are not predicted to yield a SNR greater than about 7, and FP-SPLIT is not required. Short exposures allow Earth airglow lines to be monitored. ------------------------------------------------------------------------------------------------------------------------------------ 6758( 26) - 06/13/96 11:57 - [ 12] Summary Form for Proposal 6758 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ IMAGE ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN LOCATE=EXTENDED SEARCH-SIZE=5 STEP-PATT=5 FP-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 21-Jun-1996 AND 01-Aug-1996 after 02 by 0d to 12d ONBOARD ACQ FOR 112-114,121-124,131-134,141-144,151-154 BETWEEN 21-Jun-1996 AND 01-Aug-1996 ORIENT 90D TO 90D ONBOARD ACQ FOR 212-254 BETWEEN 21-Jun-1996 AND 01-Aug-1996 ONBOARD ACQ FOR 312-354 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M G200M G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names EUROPA-WEST EUROPA-EAST EUROPA-WEST-2 GANYMEDE-WEST ------------------------------------------------------------------------------------------------------------------------------------