! File: 4491C.PROP ! Database: PEPDB ! Date: 22-FEB-1994:14:35:09 coverpage: title_1: UV SPECTROSCOPY OF THE IO PLASMA TORUS sci_cat: SOLAR SYSTEM sci_subcat: SATELLITES proposal_for: GO pi_fname: GILDA pi_mi: E. pi_lname: BALLESTER pi_inst: UNIVERSITY OF MICHIGAN pi_country: USA hours_pri: 6.17 num_pri: 1 fos: Y hrs: Y funds_length: 12 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 ! end of coverpage abstract: line_1: We propose to make the first unambiguous detection of O++ in the hot line_2: region of the Io plasma torus near Io's orbit. The abundance of this line_3: ion is diagnostic of the ion partioning in this region of the torus line_4: where Voyager could not make a definite detection, and upper limits line_5: or tentative detections made from ground-based and space-borne line_6: instruments give conflicting abundances differing by more than an line_7: order of magnitude. The long exposure required for the O++ detection line_8: will also make the first measurement of the longitudinal behavior of line_9: the strong FUV emission by the S++ torus ions. This needs to be done line_10: in the FUV, since longitudinal variations have been observed in the line_11: visible and EUV but with different characteristics. Another bonus line_12: from this long exposure will be the detection of the neutral S cloud line_13: in the torus (far from Io) in its strongest FUV multiplets. These line_14: multiplets have more certain atomic physics parameters than for the line_15: ones previously detected and will thus provide a better measure of line_16: the cloud density relevant to the torus mass loading. We will also line_17: make the first high resolution spectroscopic observation of O+, the line_18: main torus component near Io. By resolving the emission we will line_19: determine the ion's velocity distribution, which is diagnostic of line_20: the energy balance and injection of ions into the torus. ! ! end of abstract general_form_proposers: lname: BALLESTER fname: GILDA title: PI mi: E. inst: 2660 country: USA ! lname: MCGRATH fname: MELISSA mi: M. inst: 3470 country: USA ! lname: STROBEL fname: DARRELL mi: F. inst: 2380 country: USA ! lname: FELDMAN fname: PAUL mi: D. inst: 2380 country: USA ! lname: MOOS fname: WARREN inst: 2380 country: USA ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: ! question: 3 section: 1 line_1: We propose to make a long FOS G190H exposure with the 4.3" aperture line_2: of the hot region of the Io plasma torus near Io's orbit (at a line_3: radial distance from Jupiter of 5.7 Jupiter radii). The first goal line_4: of this exposure is to make the first unambiguous detection of line_5: O++ in its weak 1664 A emission, as the O++ abundance is diagnostic line_6: of the ion partioning of this region of the torus. Tentative line_7: detections made so far gave conflicting results differing by more line_8: than an order of magnitude. This 230 min exposure will span a full line_9: Jupiter rotation. The second goal is then to measure the line_10: longitudinal behavior of the brighter S++ 1729 A emission, and this line_11: will also yield the O++/S++ ion partitioning. The third goal is to line_12: measure the abundance of the neutral S cloud of the torus (far from line_13: Io), as this cloud may be an important source of torus ions through line_14: the pick-up mechanism. We also propose to take a high resolution line_15: spectrum of the torus O+ 2470 A emission with GHRS in the Echelle B line_16: mode, 2" aperture and 140 min exposure time. This emission was first line_17: positively detected with HST (McGrath et al 1993). The sensitivity line_18: and effective spectral resolution (0.194 A) are adequate to resolve line_19: this emission and determine the O+ velocity distribution in the hot line_20: torus. Voyager could not resolve the energy spectrum of each ion line_21: and the data was fitted with a common ion temperature of 60-90 eV, line_22: while models predict a highly non-Maxwellian velocity distribution line_23: for O+ showing the 57km/sec signature of the pick-up process. ! question: 4 section: 1 line_1: O++ could not be measured in the hot torus near Io's orbit by the line_2: Voyager plasma and UV experiments. Ground-based detection of its line_3: 5007 A emission is very difficult, and only upper limits have been line_4: obtained. IUE has a camera hot spot overlapping the O++ 1664 A line_5: multiplet. HUT made a 2-sigma detection of this multiplet, but there line_6: is error in the inferred abundance from the large extension of the line_7: aperture and contamination by O+ 834 A emission in 2nd order. line_8: HST/FOS is at present the only instrument that can improve the line_9: measurement of the O++ abundance. In addition, only HST can measure line_10: the longitudinal dependence of the FUV torus emissions, eg, S++ 1729 line_11: A: IUE requires more than half of a Jovian rotation. Also, only HST line_12: can make a positive detection of the 1814 and 1900 A emission by the line_13: neutral S cloud in the torus to provide a reliable density measure line_14: since these multiplets have more accurate excitation rates than the line_15: 1429 and 1479 A multiplets detected by HUT and the FOT. The 0.194 A line_16: spectral resolution of the GRHS Echelle B (extended source in LSA) line_17: is adequate to resolve the structure of the O+ 2471 A emission. line_18: The ECH-B sensitivity for the brighter S++ 1729 A line is too low. line_19: IUE's sensitivity is too low at 2471 A. The velocity distribution line_20: is hard to study from the ground: the O+ 3726,3729 A lines observed line_21: in low-resolution were weak and their analysis was difficult because line_22: they are underlined by a complex solar Fraunhofer background. ! question: 5 section: 1 line_1: Both observations of the torus west ansa require Io to be far from line_2: the field of view, to avoid scattered light contamination and direct line_3: signal from this satellite. The same applies to the other Galilean line_4: satellites. These are long exposures of a faint target. ! question: 6 section: 1 line_1: The long FOS exposure of the torus (SEQ 1.1-1.2) should be made line_2: during consecutive HST orbits, in order to assure adequate sampling line_3: to measure the longitudinal dependence of S++ emission over a single line_4: Jovian rotation (10-hours), as temporal variations may hamper the line_5: interpretation of the data. If possible, schedule sequences line_6: 2.1-2.2 and 1.1-1.2 close in time for comparison of derived torus line_7: parameters, and a more complete set of torus data not affected by line_8: temporal variations. ! question: 7 section: 1 line_1: We have extensive experience observing the torus and in reducing HRS line_2: and FOS spectra from our cycle 1 Io-torus program as well as other line_3: HST programs. The reduction of the new HST spectra should therefore line_4: be relatively straightforward. On the analysis, we have a line_5: compilation of atomic data for all the ion multiplets involved, and line_6: some detailed torus models already exist which can be implemented to line_7: address the new aspects of the proposed HST data. One of us has been line_8: involved in theoretical modelling of the torus velocity line_9: distribution, to be directly compared with the Echelle data. The line_10: atomic data for neutral sulfur is limited, but we have already line_11: studied the relevant multiplets in detail for our IUE program of SI line_12: emission from Io's atmosphere. We have been involved at different line_13: levels in observational studies addressing the torus ion-partioning, line_14: energetics and mass-loading relevant to the proposed observations. ! question: 8 section: 1 line_1: None. ! question: 9 section: 1 line_1: Program 2627 was executed on March and May, 1992. The first line_2: detection of the Io plasma torus OII 2470 A emission was made, line_3: showing significant brightness in most occasions. Based on these line_4: results we are now proposing to observe the emission in high line_5: dispersion for resolve the ion's velocity distribution. Other line_6: results of this program, which mainly concerned Io, include the line_7: determination of the spatial extent of the UV emitting region to be line_8: within 1 Io radius above the surface, a large improvement over IUE line_9: measurements. We also made the first detection of Io's albedo in the line_10: 1950--2300 A region. The data shows strong absorption by atmospheric line_11: SO2 and detailed modelling of the observed absorption features has line_12: yielded SO2 atmospheric abundances much lower than expected from line_13: previous upper limit. All Co-Is are involved in other HST line_14: projects, but these are not dedicated to studies of the Io torus. ! question: 10 section: 1 line_1: Complete computing facilities are in place and available within the line_2: Space Physics Research Lab. at the University of Michigan for use on line_3: this project. A Sun Sparcstation is available at Michigan and line_4: is connected via a local area network, in addition to SPAN and line_5: Internet. All Co-I's also have complete computing facilities at line_6: their institutions for use on this project, including a Sparcstation line_7: dedicated to HST data analysis. Extensive software libraries, line_8: including IDL as well as the standard HST data reduction line_9: software SDAS, IRAF, etc., are available in these systems. line_10: Computer hardware, software, maintenance, and management, will be line_11: made available, as well as partial salary support for all Co-Is. ! !end of general form text general_form_address: lname: BALLESTER fname: GILDA mi: E. category: PI inst: UNIVERSITY OF MICHIGAN addr_1: AOSS DEPT. city: ANN ARBOR state: MI zip: 481092143 country: USA phone: 313-747-3670 ! ! end of general_form_address records ! No fixed target records found solar_system_targets: targnum: 1 name_1: IO-TORUS-W descr_1: TORUS JUPITER lev1_1: STD = JUPITER lev2_1: TYPE=TORUS, lev2_2: LONG=90, lev2_3: LAT=0, lev2_4: RAD=4.07E5 wind_1: SEP OF IO IO-TORUS-W FROM EARTH GT 10", wind_2: SEP OF EUROPA IO-TORUS-W FROM EARTH GT wind_3: 10", SEP OF GANYMEDE IO-TORUS-W FROM wind_4: EARTH GT 10", SEP OF CALLISTO wind_5: IO-TORUS-W FROM EARTH GT 10" comment_1: WEST ANSA OF IO PLASMA TORUS, AT RADIAL comment_2: DISTANCE OF 5.7 JUPITER RADII, TO BE comment_3: OBSERVED WITH FOS AND GHRS. MINIMUM OF comment_4: ~10" SEPARATION OF ANSA FROM SATELLITES comment_5: TO AVOID CONTAMINATION OF UV SPECTRA. fluxnum_1: 1 fluxval_1: F-LINE(1729)=2.2 +/- 1 E-14 fluxnum_2: 2 fluxval_2: W-LINE(1729)=0.2 fluxnum_3: 3 fluxval_3: F-LINE(1664)=1.1 +/- 0.7 E-15 fluxnum_4: 4 fluxval_4: W-LINE(1664)=0.2 fluxnum_5: 5 fluxval_5: F-LINE(2470)=5.4 +/- 0.5 E-15 fluxnum_6: 6 fluxval_6: W-LINE(2470)=0.4 ! targnum: 2 name_1: IO-TORUS-OFFSET descr_1: SATELLITE IO lev1_1: STD = JUPITER lev2_1: STD = IO comment_1: IMAGES OF IO FOR POINTING ACCURACY comment_2: INFORMATION OF TORUS OBSERVATIONS. comment_3: IO IS USED AS AN EXAMPLE - MAY USE comment_4: ANY OTHER GALILEAN SATELLITE IF MORE comment_5: ADEQUATE (EG, IF WEST OF JUPITER). comment_6: CHOSEN SATELLITE MUST BE IN SUNLIGHT. comment_7: THE SURF_CONT(2700) OF EUROPA, comment_8: GANYMEDE AND CALLISTO ARE RESPECTIVELY comment_9: 9.1, 5.6, 2.5 TIMES LARGER THAN IO'S comment_10: (GIVEN IN FLUXVAL_3). 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 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 1.100 targname: IO-TORUS-OFFSET config: FOS/BL opmode: IMAGE aperture: 4.3 sp_element: G270H num_exp: 1 time_per_exp: 4.0 S s_to_n: 10 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=NO req_1: GROUP 1.1 - 1.2 NO GAP; req_2: CYCLE 3 / 1.1-2.2; req_3: GUIDE TOL 0.5" / 1.1-2.2; comment_1: IMAGE OF IO, IF SUNLIT, IN 4.3" FOS comment_2: APERTURE FOR POINTING ACCURACY comment_3: INFORMATION. MAY TAKE IMAGE BEFORE comment_4: OR AFTER TORUS WEST ANSA EXPOSURE 1.2. comment_5: MAY USE OTHER GALILEAN SATELLITE (IF comment_6: SUNLIT) WITH SAME EXPOSURE TIME. ! linenum: 1.200 targname: IO-TORUS-W config: FOS/BL opmode: ACCUM aperture: 4.3 sp_element: G190H num_exp: 1 time_per_exp: 230.0 M s_to_n: 5 fluxnum_1: 1 fluxnum_2: 3 fluxnum_3: 5 priority: 1 param_1: STEP-PATT=DEF, comment_1: G190H SPECTRA OF TORUS WEST ANSA FOR comment_2: DETECTION OF FAINT O++ EMISSION. comment_3: TAKE EXPOSURE IN CONSECUTIVE ORBITS comment_4: TO ATTAIN SECOND SCIENCE GOAL OF comment_5: MEASURING LONGITUDINAL DEPENDENCE OF comment_6: S++ EMISSION. ! linenum: 2.100 targname: IO-TORUS-OFFSET config: HRS opmode: IMAGE aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 96.8 S fluxnum_1: 3 priority: 2 req_2: GROUP 2.1 - 2.2 NO GAP; comment_1: IMAGE OF SUNLIT IO IN HRS LSA FOR comment_2: POINTING ACCURACY INFO. MAY TAKE comment_3: IMAGE BEFORE OR AFTER TORUS EXP. 2.2. comment_4: MAY USE EUROPA, GANYMEDE OR CALLISTO comment_5: WITH RESPECTIVE EXP. TIMES OF 10.6, comment_6: 17.4 AND 38.7 S (CORRECT IF NEEDED). ! linenum: 2.200 targname: IO-TORUS-W config: HRS opmode: ACCUM aperture: 2.0 sp_element: ECH-B wavelength: 2471 num_exp: 1 time_per_exp: 140.0 M fluxnum_1: 5 priority: 1 param_1: STEP-PATT=7, FP-SPLIT=STD, param_2: COMB=FOUR, DOPPLER=ON, param_3: STEP-TIME=0.2 comment_1: ORDER 23, ECHELLE-B SPECTRUM OF TORUS comment_2: W ANSA OII 2471 A EMISSION, TO MEASURE comment_3: SPECTRAL PROFILE TO DETERMINE THE comment_4: VELOCITY DISTRIBUTION OF THESE IONS. comment_5: IF POSSIBLE, SCHEDULE SEQUENCES comment_6: 2.1-2.2 AND 1.1-1.2 CLOSE IN TIME. ! ! end of exposure logsheet ! No scan data records found