! $Id: 5438,v 9.1 1994/07/27 17:58:42 pepsa Exp $ coverpage: title_1: IO'S ATMOSPHERE: UV SPECTROSCOPY OF NEUTRAL AND title_2: MOLECULAR COMPONENTS -- CYCLE 4 HIGH sci_cat: SOLAR SYSTEM sci_subcat: SATELLITES proposal_for: GO pi_title: DR. pi_fname: GILDA pi_mi: E. pi_lname: BALLESTER pi_inst: UNIVERSITY OF MICHIGAN pi_country: USA pi_phone: 313-747-3670 keywords_1: PLANETARY SATELLITE, PLASMA TORUS hours_pri: 9.03 num_pri: 6 fos: Y hrs: Y time_crit: Y funds_amount: 98747 funds_length: 12 funds_date: MAR-94 off_fname: NEIL off_mi: D. off_lname: GERL off_title: PROJECT REP., DRDA off_inst: UNIVERSITY OF MICHIGAN off_addr_1: 475 E. JEFFERSON off_city: ANN ARBOR off_state: MI off_zip: 48109 off_country: USA off_phone: 313-763-6438 ! end of coverpage abstract: line_1: HST observations of Io's neutral O and S FUV emissions revealed a large line_2: intensity drop as Io goes into eclipse, inconsistent with excitation of line_3: an O and S corona by torus electrons as the main excitation mechanism. line_4: Alternatively, a collapse of the bulk SO2 atmosphere or an ionospheric line_5: process possibly damped by recombination may be involved. A limited S/N line_6: HST measure of the spatial dependence of the S emission has shown that line_7: it may extend to high altitudes, far from the expected peak SO2 density, line_8: and IUE data has shown an E/W intensity asymmetry which may be related to line_9: torus asymmetries. These two observations are hard to reconcile with the line_10: eclipse picture, and we propose to make a sequence of high S/N spatial line_11: scans of the FUV emissions to measure the spatial distributions of the line_12: excitation region and of the neutral corona, respectively with optically line_13: thin and thick emissions, and to resolve any torus dependence. line_14: New FOS G190H observations have finally detected a tenous, extended SO2 line_15: atmosphere on Io's trailing side. We propose to now observe the leading line_16: side, together with trailing side observations with improved S/N, to line_17: measure asymmetries in the SO2 abundances that may arise from the line_18: distributions of SO2 frost and volcanic sources, asymmetries in the line_19: atmospheric temperature possibly related to the Io/torus interaction, line_20: and temporal variations in Io's major atmospheric component. ! ! end of abstract general_form_proposers: lname: BALLESTER fname: GILDA title: DR. mi: E. inst: 2660 country: USA ! lname: CLARKE fname: JOHN inst: 2660 country: USA ! lname: AJELLO fname: JOE inst: 2370 country: USA ! lname: SCHNEIDER fname: NICK inst: 1760 country: USA ! lname: STROBEL fname: DARRELL inst: 2380 country: USA ! lname: MCGRATH fname: MELISSA inst: 3470 country: USA ! ! end of general_form_proposers block general_form_text: ! question: 3 section: 1 line_1: A series of spatial scans of Io's O and S emissions will be made line_2: with the G140L grating on GHRS and the 2x2 arc sec aperture. These line_3: will include pairs of E/W and N/S scans when Io is at west and east line_4: elongation, and when near superior conjunction for a perpendicular line_5: geometry and looking at Io's side facing Jupiter. These scans will line_6: have Io "inside" the torus densest region, and the dependence on line_7: the torus will be studied with another pair of scans at west elong. line_8: with Io "outside" the torus plane. The spectra will cover the OI line_9: optically thick and thin 1304 and 1356 A emissions, and the SI 1251 line_10: and 1479 A emissions, with thin emissions showing the excitation line_11: source distribution and thick emissions showing also the extension line_12: of Io's neutral corona. The S/N will be 6.5 times higher than for line_13: previous SI scans. As approved by the TAC, in case the GHRS side 1 line_14: is not successfully re-activated, we will make the scans with the line_15: FOS G130H and the 1.4x4.3 arcsec aper., with a slightly lower S/N line_16: but with better spectral resolution to detect large changes in the line_17: OI 1304 A line ratios. The red leak in G130H would require a 25 line_18: min. calibration exposure on Ganymede. We will also make FOS G190H line_19: exposures of Io's leading and trailing hemispheres with the 1.4x4.3 line_20: arcsec aper. to measure the atmospheric SO2 abundance at the time line_21: of the FUV scans and asymmetries due to volcanoes and SO2 frost. line_22: Due to the variability of the phenomena, all observations should be line_23: contemporaneous. Simultaneous ground based torus obs. are planned. ! question: 4 section: 1 line_1: IUE, with typical 14-hr exposures, cannot make spatial scans. GTO line_2: WFPC 2 images of Io's FUV emissions will not resolve the optically line_3: thick and thin components, so our data will help the interpretation line_4: of these images. The low densities of Io's SO2 atmosphere are best line_5: sampled in the strong UV absorption bands at 2000 A, which can only line_6: be accessed with HST (the flux is too low for IUE). Our cycle 3 line_7: observations with FOS G190H and the 0.3 arc sec circular aperture line_8: were aimed at various regions on Io to measure large changes in the line_9: atmosphere/surface, but the S/N is not high enough to measure the line_10: temperature dependence of the emission, and the leading hemisphere line_11: will not be observed either. So far only ground-based millimeter line_12: observations can detect Io's atmospheric SO2 but mainly the hot, line_13: dense SO2 patches possibly related to volcanic regions, and not the line_14: low SO2 densities that HST can sample. On Galileo, only one of the line_15: UV instruments will be useful and our HST data will be used for the line_16: science planning of this mission due to reach Jupiter in late 1995 line_17: (the resolution of the second UV instrument is too low). Ground- line_18: based observations have been made of the OI 6300 A emission near line_19: Io, but such difficult observations do not give spatial information line_20: and do not sample the atmosphere directly, which makes our HST data line_21: unique. Besides torus electron excitation, the 6300 A emissions line_22: require an additional source involving SO/SO2 molecules but also line_23: depending on the torus, interesting for comparison with our data. ! question: 5 section: 1 line_1: Dark time is essential for all the FUV spatial scans to avoid line_2: contamination by 1304 A airglow that would make interpretation of line_3: the scans difficult. Io must be acquired and its center determined line_4: to within roughly 0.10 arc sec. Because of temporal variability of line_5: Io's atmosphere and torus parameters, all the observations should line_6: be made close in time. Three sets of the GHRS scans will be made line_7: with Io inside the densest torus region as it crosses the torus line_8: plane around Sys. III longitude 292 deg., within +/- 45 deg. (the line_9: region around longitude 112 deg. has different characteristics). line_10: The fourth set of scans will be made with Io outside this region, line_11: when farthest from the plane around torus longitude 202 or 22 deg., line_12: within +/- 45 deg. The FOS/SO2 observations are assumed independent line_13: of the torus parameters. We have found an HST observing sequence line_14: spanning 2 orbits of Io that fits all above requisites. Each obs. line_15: is specified by Io's orbital phase and Jupiter's central meridian line_16: longitude (CML) defining the torus longitude where Io is embedded: line_17: No) OBS TYPE IO ORB PHASE JUPITER CML TORUS LONG OF IO line_18: 1) SO2 ~ W elong. ~270 line_19: 2) SO2 ~E elong. ~90 line_20: 3) scans ~W elong. ~270 22 +/- 45 292 +/- 45 "in" line_21: 4) scans ~W elong. ~270 112 +/- 45 22 +/- 45 "out" line_22: 5) scans near Sup.C. ~340 92 +/- 45 292 +/- 45 "in" line_23: 6) scans ~E elong. ~90 202 +/- 45 292 +/- 45 "in" ! question: 6 section: 1 line_1: Dark time is essential for all the FUV spatial scans due to line_2: potential contamination by 1304 airglow that makes the line_3: interpretation of the scans difficult. ! ! question: 8 section: 1 line_1: None. ! question: 9 section: 1 line_1: GO 2602 - "The Excitation of Atmospheres of Planetary Satellites" line_2: J. Clarke PI, J. Ajello and N. Schneider Co-I's -directly related. line_3: GO 2627 - "Io's Atmosphere and its Interaction with the Torus" line_4: Co-I's: M. McGrath, G. Ballester - directly related. line_5: GO 4600 - "FUV Spectroscopy of Io's Armosphere", line_6: J. Clarke PI, J. Ajello, N. Schneider, M. McGrath and many other line_7: unrelated GO programs on upper atmospheres of the outer planets, line_8: Venus, Mars and the ISM with J. Clarke or M.Mcgrath PI's or Co-I's line_9: and/or other Co-I's in the present program as Co-I's: GO 2393, line_10: 2602, 2603, 2625, 2627, 3511, 3616, 3617, 3618, 3862, 4600, ???, line_11: 4601, GO/AR 4604, as well and other new cycle 4 programs. The main line_12: results obtained from the related programs are: GO 2602: Excellent line_13: spectra of Io entering eclipse - resolved FUV emission region, line_14: found sharp decrease of line strength in shadow, characterizing the line_15: time scales, and near-UV albedo spectrum shows signature of surface line_16: properties, with possible evidence for varaible SO2 atmospheric line_17: columns. GO 2627: Executed in spring 1992 - best determination of line_18: spatial extent of FUV airglow. First 1600-2300 A albedo measurement line_19: with positive detection of Io's SO2 atmosphere showing a much line_20: thinner SO2 atmosphere than expected. GO 4600: Only few exposures line_21: could be successfully scheduled. FOS G190H small aperture exposures line_22: of the Pele region and a bright region on the trailing hemisphere line_23: show variations possibly from more SO2 frost in the bright region. ! question: 10 section: 1 line_1: Complete computing facilities are in place and available within line_2: the Space Physics Research Lab. at the University of Michigan for line_3: use on this project. Two Sparcstations, including a Sun IPX line_4: procured with cycle 1 GO funding, and a VAX 8600 are available for line_5: this project and are connected via a local area network, in line_6: addition to the Michigan network MERIT, SPAN, and Internet. All line_7: Co-I's also have complete computing facilities at their line_8: institutions for use on this project. In addition, the laboratory line_9: work of J. Ajello and collaborators is proceeding with input from line_10: the HST data and with independent funding ! !end of general form text general_form_address: lname: BALLESTER fname: GILDA mi: E. category: PI inst: 2660 addr_1: AOSS DEPT. city: ANN ARBOR state: MI zip: 481092143 country: USA phone: 313-747-3540 ! ! end of general_form_address records ! No fixed target records found solar_system_targets: targnum: 1 name_1: IO-SCAN-W-IN descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO wind_1: OLG OF IO BETWEEN 240 300, CML OF wind_2: JUPITER FROM EARTH BETWEEN 337 67, wind_3: OLG OF JUPITER BETWEEN 330 30, wind_4: SEP OF EUROPA IO FROM EARTH GT 10", wind_5: SEP OF GANYMEDE IO FROM EARTH GT 10", wind_6: SEP OF CALLISTO IO FROM EARTH GT 10" comment_1: OBSERVE IO WITHIN +/- 30 DEGREES OF comment_2: WEST ELONGATION, WHEN INSIDE THE TORUS comment_3: DENSE REGION AROUND LONGITUDE 292, AND comment_4: WHEN JUPITER IS NEAR OPPOSITION comment_5: (PREFERABLY BEFORE OPPOSITION). fluxnum_1: 1 fluxval_1: SURF(V) = 5.0 +/- 0.5 fluxnum_2: 2 fluxval_2: SIZE = 1.0 +/- .2 fluxnum_3: 3 fluxval_3: F-LINE(1304)=2.1 +/- 1E-13 fluxnum_4: 4 fluxval_4: W-LINE(1304)=0.01 ! targnum: 2 name_1: IO-SCAN-W-OUT descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO wind_1: OLG OF IO BETWEEN 240 300, CML OF wind_2: JUPITER FROM EARTH BETWEEN 67 157, wind_3: OLG OF JUPITER BETWEEN 330 30, wind_4: SEP OF EUROPA IO FROM EARTH GT 10", wind_5: SEP OF GANYMEDE IO FROM EARTH GT 10", wind_6: SEP OF CALLISTO IO FROM EARTH GT 10" comment_1: OBSERVE IO WITHIN +/- 30 DEGREES OF comment_2: WEST ELONGATION, WHEN OUTSIDE THE TORUS comment_3: DENSE REGION AROUND LONGITUDE 22, comment_4: AND WHEN JUPITER IS NEAR OPPOSITION comment_5: (PREFERABLY BEFORE OPPOSITION). fluxnum_1: 1 fluxval_1: SURF(V) = 5.0 +/- 0.5 fluxnum_2: 2 fluxval_2: SIZE = 1.0 +/- .2 fluxnum_3: 3 fluxval_3: F-LINE(1304)=2.1 +/- 1E-13 fluxnum_4: 4 fluxval_4: W-LINE(1304)=0.01 ! targnum: 3 name_1: IO-SCAN-E-IN descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO wind_1: OLG OF IO BETWEEN 60 120, CML OF wind_2: JUPITER FROM EARTH BETWEEN 147 337, wind_3: OLG OF JUPITER BETWEEN 330 30, wind_4: SEP OF EUROPA IO FROM EARTH GT 10", wind_5: SEP OF GANYMEDE IO FROM EARTH GT 10", wind_6: SEP OF CALLISTO IO FROM EARTH GT 10" comment_1: OBSERVE IO WITHIN +/- 30 DEGREES OF comment_2: EAST ELONGATION, WHEN INSIDE THE TORUS comment_3: DENSE REGION AROUND LONGITUDE 292, AND comment_4: WHEN JUPITER IS NEAR OPPOSITION comment_5: (PREFERABLY BEFORE OPPOSITION). fluxnum_1: 1 fluxval_1: SURF(V) = 5.0 +/- 0.5 fluxnum_2: 2 fluxval_2: SIZE = 1.0 +/- .2 fluxnum_3: 3 fluxval_3: F-LINE(1304)=2.1 +/- 1E-13 fluxnum_4: 4 fluxval_4: W-LINE(1304)=0.01 ! targnum: 4 name_1: IO-SO2-W descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO wind_1: OLG OF IO BETWEEN 240 300, wind_2: OLG OF JUPITER BETWEEN 330 30 wind_3: SEP OF EUROPA IO FROM EARTH GT 10", wind_4: SEP OF GANYMEDE IO FROM EARTH GT 10", wind_5: SEP OF CALLISTO IO FROM EARTH GT 10" comment_1: OBSERVE IO WITHIN +/- 30 DEGREES OF comment_2: WEST ELONGATION, WHEN JUPITER IS NEAR comment_3: OPPOSITION (PREFERABLY BEFORE comment_4: OPPOSITION). fluxnum_1: 1 fluxval_1: SURF(V) = 5.0 +/- 0.5 fluxnum_2: 2 fluxval_2: SIZE = 1.0 +/- .2 fluxnum_3: 3 fluxval_3: SURF-CONT(2700) = 2 +/- 1 E-13 fluxnum_4: 4 fluxval_4: SURF-CONT(1900) = 1.5 +/- 1 E-15 ! targnum: 5 name_1: IO-SO2-E descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO wind_1: OLG OF IO BETWEEN 60 120, wind_2: OLG OF JUPITER BETWEEN 330 30 wind_3: SEP OF EUROPA IO FROM EARTH GT 10", wind_4: SEP OF GANYMEDE IO FROM EARTH GT 10", wind_5: SEP OF CALLISTO IO FROM EARTH GT 10" comment_1: OBSERVE IO WITHIN +/- 30 DEGREES OF comment_2: EAST ELONGATION, WHEN JUPITER IS NEAR comment_3: OPPOSITION (PREFERABLY BEFORE comment_4: OPPOSITION). fluxnum_1: 1 fluxval_1: SURF(V) = 5.0 +/- 0.5 fluxnum_2: 2 fluxval_2: SIZE = 1.0 +/- .2 fluxnum_3: 3 fluxval_3: SURF-CONT(2700) = 2 +/- 1 E-13 fluxnum_4: 4 fluxval_4: SURF-CONT(1900) = 1.5 +/- 1 E-15 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 1.100 sequence_1: DEFINE sequence_2: SO2OBS targname: # config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 300 S fluxnum_1: 3 priority: 1 param_1: Y-SIZE = 5, param_2: Y-SPACE = 128, param_3: COMB = YES, param_4: SUB-STEP = 4 req_1: SEQ 1.1-1.3 NOGAP; req_2: INT ACQ FOR 1.2; req_3: CYCLE 4 / 1.1-1.3 comment_1: IO INTERACTIVE ACQUISITION IN 4.3 ARC comment_2: SEC APERTURE: SET OF 5 SPECTRA AT comment_3: DIFFERENT Y-DEFLECTIONS TO DETERMINE comment_4: CENTERING IN X AND Y, THEN UPLINK HST comment_5: POINTING CORRECTION INFORMATION. comment_6: REQUIRES REAL-TIME. ! linenum: 1.200 sequence_1: DEFINE sequence_2: SO2OBS targname: # config: FOS/BL opmode: ACCUM aperture: 4.3 sp_element: G190H num_exp: 1 time_per_exp: 52M s_to_n: 80 s_to_n_time: 52M fluxnum_1: 4 priority: 1 param_1: STEP-PATT=SINGLE comment_1: G190H SPECTRA OF IO'S DISK IN. comment_2: 4.3 ARC SEC APERTURE. linenum: 1.300 sequence_1: DEFINE sequence_2: SO2OBS targname: # config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 240 S fluxnum_1: 3 priority: 2 param_1: STEP-TIME=1.0, param_2: SUB-STEP=1, param_3: Y-SIZE=4, param_4: Y-SPACE=64, param_5: COMB=YES comment_1: IMAGE OF IO comment_2: IN 4.3 APER. FOR POST-OBS POINTING comment_3: INFORMATION. ! linenum: 2.100 sequence_1: DEFINE sequence_2: SCAN2 targname: # config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 10S fluxnum_1: 3 priority: 1 param_1: SEARCH-SIZE=5 ! param_2: LOCATE=EXTENDED ! use if available req_2: ONBOARD ACQ FOR 2.4; req_3: SEQ 2.1-2.4 NO GAP; req_4: CYCLE 4 / 2.1 - 2.4 comment_1: ONBOARD ACQ OF IO WITH N2. comment_2: PLEASE USE INFORMATION FROM EARLIER comment_3: IO ACQ'S FOR STEP-TIME: ESTIMATED comment_4: STEP-TIME = 0.4. ! linenum: 2.200 sequence_1: DEFINE sequence_2: SCAN2 targname: # config: HRS opmode: RAPID aperture: 2.0 sp_element: G140L num_exp: 1 time_per_exp: 10 M s_to_n: 8 s_to_n_time: 1M fluxnum_1: 3 fluxnum_2: 4 priority: 1 param_1: SAMPLE-TIME=10 req_1: SPATIAL SCAN SINGLE-EXP; req_2: CYCLE 4; req_3: DARK TIME; comment_1: SPATIAL SCAN NORTH/SOUTH ACROSS IO comment_2: DISK AND EXTENDED CORONA +/-2.5 ARC comment_3: SEC FROM DISK CENTER. THIS N/S SCAN comment_4: SHOULD BE SEQUENTIAL (NO GAP) TO THE comment_5: E/W SCAN OF THE SAME TARGET. ! linenum: 2.300 sequence_1: DEFINE sequence_2: SCAN2 targname: # config: HRS opmode: RAPID aperture: 2.0 sp_element: G140L num_exp: 1 time_per_exp: 26M s_to_n: 8 s_to_n_time: 1M fluxnum_1: 3 fluxnum_2: 4 priority: 1 param_1: SAMPLE-TIME=10 req_1: SPATIAL SCAN SINGLE-EXP; req_2: DARK TIME; comment_1: SPATIAL SCAN EAST/WEST ACROSS IO DISK comment_2: AND EXTENDED CORONA +/-2.5 ARC SEC comment_3: FROM DISK CENTER. ! linenum: 2.400 sequence_1: DEFINE sequence_2: SCAN2 targname: # config: HRS opmode: IMAGE aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 96.8S fluxnum_1: 3 priority: 1 comment_1: IMAGE OF IO IN LSA AFTER CENTERING. comment_2: ESTIMATED COUNTS/DWELL POINT FROM comment_3: IO DISK = 100. ! ! linenum: 10.000 sequence_1: USE sequence_2: SO2OBS targname: IO-SO2-W req_1: GROUP 10-40 WITHIN 212H; comment_1: G190H SPECTRA OF IO'S TRAILING comment_2: HEMISPHERE. comment_3: TAKE CLOSE IN TIME TO LINENUM 11. ! linenum: 11.000 sequence_1: USE sequence_2: SO2OBS targname: IO-SO2-E comment_1: G190H SPECTRA OF IO'S LEADING comment_2: HEMISPHERE. comment_3: TAKE CLOSE IN TIME TO LINEMUM 10, comment_4: PREFERABLY SEPARATED BY THE comment_5: MINIMUM OF ~ 21 HOURS. ! linenum: 20.000 sequence_1: USE sequence_2: SCAN2 targname: IO-SCAN-W-IN comment_1: SPATIAL SCAN NORTH/SOUTH comment_2: AND EAST/WEST OF IO'S comment_3: DISK/CORONA +/-2.5 ARCSEC FROM CENTER comment_4: WITH IO NEAR WEST ELONG. AND INSIDE comment_5: TORUS DENSE REGION NEAR LONGITUDE 292 comment_6: (OR 112 - MUST BE SAME AS LINE 40.00) ! linenum: 30.000 sequence_1: USE sequence_2: SCAN2 targname: IO-SCAN-W-OUT comment_1: SPATIAL SCAN NORTH/SOUTH comment_2: AND EAST/WEST OF IO'S comment_3: DISK/CORONA +/-2.5 ARCSEC FROM CENTER, comment_4: WITH IO NEAR WEST ELONG. AND OUTSIDE comment_5: TORUS DENSE REGION NEAR LONGITUDE 22 comment_6: (OR 202) ! linenum: 40.000 sequence_1: USE sequence_2: SCAN2 targname: IO-SCAN-E-IN comment_1: SPATIAL SCAN NORTH/SOUTH comment_2: AND EAST/WEST OF IO'S comment_3: DISK/CORONA +/-2.5 ARCSEC FROM CENTER, comment_4: WITH IO NEAR EAST ELONG. AND INSIDE comment_5: TORUS DENSE REGION NEAR LONGITUDE 292 comment_6: (OR 112 - MUST BE SAME AS LINE 20.0) ! ! end of exposure logsheet scan_data: line_list: 2.2 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 5.0000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.008333 first_line_pa: 20.0000 scan_frame: CEL len_offset: 2.5000 wid_offset: 0.0000 ! line_list: 2.3 fgs_scan: cont_dwell: C dwell_pnts: 0 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 5.0000 sides_angle: 90.0000 number_lines: 1 scan_rate: 0.003205 first_line_pa: 110.0000 scan_frame: CEL len_offset: 2.5000 wid_offset: 0.0000 ! ! end of scan data