! File: 2602C.PROP ! Database: PEPDB ! Date: 17-FEB-1994:09:04:27 coverpage: title_1: THE EXCITATION OF THE ATMOSPHERES OF PLANETARY SATELLITES sci_cat: SOLAR SYSTEM proposal_for: GO pi_title: DR. pi_fname: JOHN pi_mi: T. pi_lname: CLARKE pi_inst: MICHIGAN, UNIVERSITY OF pi_country: USA pi_phone: 313-747-3540 keywords_1: PLANETARY SATELLITE, PLASMA TORUS, AURORA hours_pri: 2.00 num_pri: 2 fos: X time_crit: X funds_amount: 75455 funds_length: 12 funds_date: OCT-91 off_fname: MARTIN off_mi: H. off_lname: TOBIN off_title: ASSISTANT DIRECTOR off_inst: THE UNIVERSITY OF MICHIGAN off_addr_1: DIV. OF RESEARCH DEVELOPMENT AND ADMINISTRATION off_addr_2: 245 W. ENG. BLDG. off_addr_3: 550 E. UNIV. STREET off_city: ANN ARBOR off_state: MI off_zip: 48109 off_country: USA ! end of coverpage abstract: line_1: We will observe Io at near and far UV wavelengths in a set of line_2: observations designed to study the excitation of the satellite atmospheres. line_3: The distinguishing element of this program is the design of the observations to line_4: separate the following processes: resonant scattering of solar emission, line_5: charged particle excitation by magnetospheric plasma, and (in the case of Io) line_6: the decay of the atmosphere in the absence of solar-driven sublimation from the line_7: surface. Io will be observed with the FOS/HST combination in the far-UV over a line_8: period of time centered on the passage of Io into eclipse to separate the solar line_9: emissions (while sunlit) from particle excited emissions (while in shadow) and line_10: the near UV SO2 aurora will be observed while Io is in shadow. The far UV line_11: lines of atomic sulfur and oxygen emanate from an extended atmosphere, and are line_12: produced by a combination of resonant scattering of solar emission and plasma line_13: impact relatively high in the atmosphere. The near-UV bands of SO reflect line_14: particle impact on SO2, the parent molecule believed to be driven by line_15: sublimation vapor pressure from the surface, and may be excited relatively line_16: closer to Io's surface (due to the 3 times smaller scale height) by incident line_17: plasma and/or ionospheric processes. ! ! end of abstract general_form_proposers: lname: CLARKE fname: JOHN title: P.I. mi: T. inst: MICHIGAN, UNIVERSITY OF country: USA ! lname: LUHMANN fname: JANET inst: CALIFORNIA, UNIVERSITY OF, LOS ANGELES country: USA ! lname: AJELLO fname: JOE inst: JET PROPULSION LABORATORY country: USA ! lname: SCHNEIDER fname: NICK inst: UNIVERSITY OF COLORADO country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The observations will consist of: i) a series of FOS/blue 4.3 arc line_2: sec aperture 15 min. RAPID spectra of Io beginning 10-15 minutes line_3: before eclipse disappearance of Io for a period of 40 min. (or as line_4: long as possible in one dark orbit), and ii) a series of FOS G270H line_5: 4.3 arc sec aperture 15 min. RAPID spectra beginning near line_6: the time of eclipse disappearance for one dark orbit. The total is 2 line_7: dark orbits with the priority listed above. Acquisition of Io requires line_8: short spectra at different y-deflections to center in y (IO_TA). line_9: Using the 4.3 arc sec aperture to optimize the sensitivity to line_10: diffuse emission, we request coarse track to avoid any loss of line_11: lock. In both cases, Io is to be observed when it is in the active line_12: sector of Jupiter's magnetic field and also in the Io plasma torus, line_13: i.e. when the sub-Io CML of Jupiter is 240-310 degrees. Io line_14: must also be observed when the sun-Earth-Jupiter angle is 90 +/- 25 line_15: degrees so that the HST can see Io in the shadow of Jupiter. This line_16: will place our line of sight in the sunlit geocorona, with bright line_17: OI 1304 and HI 1216 emissions, which must be subtracted. ! question: 4 section: 1 line_1: The line emissions excited by the impact of magnetospheric plasma line_2: at Io are radiated chiefly in the FUV, and require a line_3: space- based instrument with high sensitivity and angular resolution line_4: to be detected. No ground-based instruments today are capable of line_5: detecting atmospheric line emissions from Io. line_6: Emissions from the extended atmosphere of Io are just detectable line_7: with the IUE, but higher sensitivity and angular resolution will be line_8: required to determine the source region and spatial distribution. We line_9: have performed observation (ii) above with the IUE, with good line_10: tracking on Io and minimal scattered light from Jupiter, but no SO2 line_11: detection. Only the HST is fast enough to detect changes in emission line_12: brightness through the eclipse disappearance. Io is believed to be line_13: the initial source of the plasma in Jupiter's magnetosphere, and we are line_14: proposing to observe the source region of that plasma localized in the line_15: atmosphere of Io. The angular resolution and sensitivity of HST line_16: are crucial to the success of this observation. ! question: 5 section: 1 line_1: As discussed above, the efficiency of the HST/FOS to a 1 arc sec line_2: object with G130H is roughly 0.5 cts/sec-kR for diffuse emission; line_3: HST/FOS with G270H and 1 arc sec aperture will yield roughly 2 line_4: cts/sec-kR. The S/N estimates given above are based on 30-40 min. line_5: integrations in a single dark orbit per observation. The time for line_6: acquisition of two guide stars in coarse track (no fine lock) is line_7: estimated to be 5 min. FOS acquisitions cannot be used while tracking line_8: Io with track 51, so a real-time uplink is needed to center Io in line_9: the Y-direction (1.3 arc sec diode length). We will accept the blind line_10: blind ponting in X. We define a target IO-TA for 5 spectra of Io in line_11: sunlight at different y-deflections: the real-time uplink will be used line_12: to select the optimum y-deflection for the science data. We request line_13: 40 min. per orbit observing time with Io in shadow, consistent with the line_14: original RPSS proposal and TAC time assignment. ! question: 6 section: 1 line_1: The observations of Io must begin 10-15 minutes before Io line_2: eclipse disappearance, and must be scheduled when Io is line_3: firmly inside the torus plasma and in the active sector of line_4: Jupiter's magnetosphere. To be able to follow Io in the shadow line_5: of Jupiter, the sun-Earth-Jupiter angle must be 90 +/- 25 line_6: degrees, and we must observe when Io is going into eclipse line_7: rather than coming out in case the atmosphere collapses when line_8: Io cools down in the shadow of Jupiter. In fact, we hope to line_9: observe this collapse as Io moves into shadow. ! question: 7 section: 1 line_1: Line_2: excitation of SO2 gas (J.A.). We have measured the line_3: electron impact induced fluorescence spectrum of SO2 in the UV line_4: (400-2000 A). The results of these studies show that the strongest line_5: features in the vavelenght range of HRS occur between 1200-1500 A and line_6: include resonance lines of SI, SII, SIII, and OI. For these features line_7: we have measured excitation functions from 0-400 eV for modeling the line_8: excitation rates at Io. The analysis of these spectra will be line_9: greatly aided by our laboratory studies of electron excitation of SO2. line_10: The relative strengths of the various lines will allow line_11: us to estimate the bulk composition and vertical thickness of Io's line_12: atmosphere, and the absolute intensity of the observed emission can be line_13: related to the total ionization rate and therefore the mass supply rate line_14: into the plasma torus. Through the measurements of solar scattering, line_15: particle excitation, and the several time scales for atmospheric line_16: collapse, we hope to obtain a definitive picture of the production and line_17: excitation of Io's atmosphere. The spectra will be reduced line_18: using standard routines. The temporal variation of the emission line_19: features in the Io data before and after eclipse will be interpreted line_20: in terms of a model for the various emission processes discussed line_21: above. We hope to separate the strengths of the different processes line_22: by fitting components with different time scales to the measured line_23: variation in brightness of each individual line. ! question: 10 section: 1 line_1: Complete computing facilities are in place and available within the line_2: Space Physics Research Lab. for use on this project. Two VAX 750's line_3: and a VAX 8600 are accessible via a local area network, in addition to line_4: the Michigan network (MERIT) and the SPAN network. A SUN 4/110 work- line_5: station running IDL is available through start-up funds awarded to line_6: Professor Clarke. In addition to the above resources, three color line_7: graphics workstations, with hard copy capability, are available to line_8: provide high quality output for publications. ! !end of general form text general_form_address: lname: CLARKE fname: JOHN mi: T. title: DR. category: PI inst: UNIVERSITY OF MICHIGAN addr_1: AOSS DEPT. city: ANN ARBOR state: MI zip: 481092143 country: USA ! ! end of general_form_address records ! No fixed target records found solar_system_targets: targnum: 1 name_1: IO descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO wind_1: OLG OF JUPITER BETWEEN 54 104, wind_2: ECL U OF IO BY JUPITER, wind_3: CML OF JUPITER FROM IO BETWEEN 240 310, 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 GOING INTO ECLIPSE comment_2: BEHIND JUPITER; BEGIN G130H SERIES comment_3: 10-20 MIN AND G270H SERIES 0-9 comment_4: MINUTES BEFORE IO ECLIPSE comment_5: DISAPPEARANCE AND SCHEDULE comment_6: WHEN EARTH-SUN-JUPITER ANGLE IS comment_7: 54-104 DEGREES AND CML OF SUB-IO comment_8: POINT ON JUPITER IS 240-310 DEG. comment_9: PLEASE NOTE THAT THE WINDOWS CAN comment_10: BE EXPANDED IF NEEDED TO SCHEDULE. fluxnum_1: 1 fluxval_1: SURF(V) = 5.8 +/- 0.5 fluxnum_2: 2 fluxval_2: SIZE = 1.0 +/- .2 fluxnum_3: 3 fluxval_3: SURF-CONT(2700) = 2 +/- 1 E-13 ! targnum: 2 name_1: IO-TA descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO comment_1: IO-TA IS IO IN SUNLIGHT FOR TARGET comment_2: ACQUISITION WITH FOS. THIS WILL BE A comment_3: SET OF 5 SPECTRA AT DIFFERENT comment_4: Y-DEFLECTIONS TO DETERMINE WHERE IO comment_5: IS CENTERED ON THE 1.3 ARC SEC LONG comment_6: FOS DIODES. fluxnum_1: 1 fluxval_1: SURF(V) = 5.8 +/- 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(1600) = 2 +/- 1 E-14 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 1.000 targname: IO-TA config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 300 S fluxnum_1: 2 priority: 1 param_1: Y-SIZE = 5 param_2: Y-SPACE = 128 param_3: COMB = YES param_4: SUB-STEP = 4 req_1: RT ANALYSIS FOR 2-3.1; req_2: CYCLE 1 /1-6.1; comment_1: FOS SPECTRA OF IO FOR TARGET ACQ. comment_2: BEFORE EA. OF 2 SPECTROSCOPY SESSIONS: comment_3: W/ G130H AND G270H. REQUIRES RT UPLINK comment_4: WILL UPLINK CORRECT POINTING DURING comment_5: EARTH OCC BASED ON 5 SPECTRA IN OSS comment_6: IO WILL BE RE-ACQ'D.TAKE 2-3 POST OCC. ! linenum: 2.000 targname: IO-TA config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 4.0 S fluxnum_1: 2 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 = NO req_1: SEQ 2-3.1 NO GAP; comment_1: QUICK MAP OF 4.3 APERTURE,AFTER UPLINK comment_2: CORRECTING POINTING, TO DETERMINE TRUE comment_3: LOCATION OF IO IN APERTURE. ! linenum: 3.000 targname: IO config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G130H wavelength: 1368. num_exp: 1 time_per_exp: 1590S fluxnum_1: 1 priority: 1 param_1: STEP-PATT = DEF param_2: READ-TIME = 40 req_1: CYCLE 1 comment_1: BEGIN EXPOSURES AFTER ACQ MAP comment_2: AND 5-10 MINUTES BEFORE IO comment_3: ECLIPSE DISAPPEARANCE. ! linenum: 3.100 targname: IO config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G130H wavelength: 1368. num_exp: 1 time_per_exp: 170S fluxnum_1: 1 priority: 1 param_1: STEP-PATT = DEF param_2: READ-TIME = 40 req_1: CYCLE 1 ! linenum: 4.000 targname: IO-TA config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 300 S fluxnum_1: 2 priority: 1 param_1: Y-SIZE = 5 param_2: Y-SPACE = 128 param_3: COMB = YES param_4: SUB-STEP = 4 req_1: CYCLE 1; req_2: RT ANALYSIS FOR 5-6.1 comment_1: 5-STEP IMAGE FOR RT POINTING comment_2: CORRECTION BEFORE 5,6. MUST OCCUR comment_3: WITH IO IN SUNLIGHT. ! linenum: 5.000 targname: IO-TA config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 4.0 S fluxnum_1: 2 priority: 3 param_1: STEP-TIME = 1.0 param_2: SUB-STEP = 1 param_3: Y-SIZE = 4 param_4: Y-SPACE = 64 param_5: COMB = NO req_1: SEQ 5-6.1 NO GAP; comment_1: QUICK MAP OF 4.3 APER FOR comment_2: GROUND TRUTH POINTING INFO. comment_3: MUST OCCUR BEFORE LINE 6. ! linenum: 6.000 targname: IO config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 1590S fluxnum_1: 1 priority: 1 param_1: STEP-PATT = DEF param_2: READ-TIME = 40. comment_1: 40 S. SPECTRA OF IO: BEGIN 0-5 comment_2: MIN. BEFORE ECLIPSE OF IO BY comment_3: JUPITER. ! linenum: 6.100 targname: IO config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 170S fluxnum_1: 1 priority: 1 param_1: STEP-PATT = DEF param_2: READ-TIME = 40. ! ! end of exposure logsheet ! No scan data records found