! $Id: 5385,v 7.1 1994/07/27 17:22:34 pepsa Exp $ coverpage: title_1: DETECTING THE HYDROXYL RADICAL IN THE JOVIAN MAGNETOSPHERE sci_cat: SOLAR SYSTEM sci_subcat: GIANT PLANETS proposal_for: GO pi_fname: DONALD pi_mi: E. pi_lname: SHEMANSKY pi_inst: UNIV. OF SOUTHERN CALIFORNIA pi_country: USA hours_pri: 10.00 num_pri: 1 fos: Y funds_amount: 65000 funds_length: 12 off_fname: WILLIAM off_lname: SPITZER off_title: INTERIM PROVOST/VP off_inst: UNIV. OF SOUTHERN CALIFORNIA off_addr_1: DEPT. OF CONTRACTS AND GRANTS off_addr_2: UNIV. OF SOUTHERN CALIFORNIA off_city: LOS ANGELES off_state: CA off_zip: 90089 off_country: USA off_phone: 213-740-7762 ! end of coverpage abstract: line_1: We propose to observe the Jupiter magnetosphere to determine the line_2: presence and abundance of the hydroxyl radical(OH). OH has been seen line_3: in the region of the icy moons of Saturn by the HST/FOS instrument line_4: (GO3644-Cycle 2, August, 1992). The observed abundance implied a line_5: source rate 20 times higher than predicted on the basis of ion surface line_6: sputtering of H_2O. Plasma content at the orbit of Europa is greater line_7: than at Saturn. Sputtering source rates of 3x10^26 mol/s are predicted, line_8: or about 1/6 to 1/3 the rate inferred at Saturn's icy satellites. line_9: OH may contribute a substantial fraction of OII to the outward moving line_10: Io torus plasma. Our physical chemistry model predicts that for a 40% line_11: contribution to local plasma density, the Europan sourced OH number line_12: density may approach an average of 3 cm^-3. Assuming a path length line_13: of 10 R_j, with an OH emission probability of 2.3x10^-5 s^-1 in the line_14: OH A-X (0,0) band near 3085 Angstroms the intensity is 5 Rayleighs. line_15: This should be observable by the HST/FOS. If the high source rate of line_16: OH at Saturn is driven by micrometeoritic gardening of the satellite line_17: surfaces, then the same process may be active at Europa, producing a line_18: commensurately higher signal. Direct estimates of OH densities along line_19: with physical chemistry modeling will provide definitive constraints line_20: on possible surface erosion rates of Europa's surface. ! ! end of abstract general_form_proposers: lname: SHEMANSKY fname: DONALD title: PI mi: E. inst: UNIV. OF SOUTHERN CALIFORNIA country: USA ! lname: MATHESON fname: PHILIP mi: L. inst: UNIV. OF SOUTHERN CALIFORNIA country: USA ! lname: HU fname: HONGYAO mi: D. inst: UNIV. OF SOUTHERN CALIFORNIA country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The observations consists of 8 hours signal integration time at line_2: 670000km (9.4R_J) from Jupiter's center on the dusk side in the line_3: equatorial-satellite orbital plane. This is the location of Europa's line_4: orbit. Ganymede, Callisto or Europa, itself, will be used for onboard line_5: aquisition to remove the zero-point error in the ephermeris with line_6: respect to the guide stars. The aperture will then be offset to the line_7: desired location. The observation is to be made with when no satellites line_8: are in the field of view. The FOS Red Digicon will be used with the line_9: G270H grating and the 2.0-Bar aperture. The Red Digicon with the G270H line_10: yields the greatest detection efficiency at the OH 3085A band. The line_11: 2.0-bar aperture is the largest available for our desired resolution line_12: and is selected here because a maximal field of view is necessary to line_13: enhance the signal-to-noise ratio (SNR). The experience of our last line_14: HST observation (GO3644, Cycle-2) suggests that to achieve a SNR of line_15: ~5 for the expected 5 Rayleigh OH 3085A band, an exposure of at least line_16: 8 hours is necessary. ! question: 4 section: 1 line_1: Our previous experience (GO3644 Cycle-2) shows that the HST provides an line_2: excellent platform for the detection of extremely faint UV signals. An line_3: extraterrestrial OH A-X (0,0) feature cannot be detected with ground line_4: based apparatus because of strong airglow foreground signals and line_5: atmospheric absorption. The IUE spacecraft has detected the OH band in line_6: comets, but the intensity expected for Jupiter's magnetosphere lies line_7: below its detection threshold. The HST is the only currently operating line_8: platform from which these observations can be performed. ! question: 4 section: 2 line_1: CYCLE-2 GO 3644 observation a 37 Rayleigh OH A-X (0,0) emissions at line_2: Saturn was obtained with the HST FOS with a SNR ~ 5 with 3.5 hours of line_3: exposure time. The HST instrument configuration was identical to that line_4: proposed here. Solar scattering from Saturn's rings was the dominant line_5: source of signal in the detector. The signal strength of the OH 3085A line_6: feature near the orbit of Europa at 9.4 R_j is expected to be 5 R, with line_7: source filling the 2.0-bar aperture, so the throughput is comparable to line_8: that of non-occulting apertures at 3100 Angstroms. The peak source line_9: brightness is anticipated to be f_lambda=0.26 Rayleighs per angstrom at line_10: 3085A. For a throughput of 0.04 the required exposure time to obtain line_11: a SNR ~ 5 is 7 hours. Estimates of the noise are complicated by the line_12: lack of estimates of solar scattering from the planet. However, line_13: CYCLE-2 GO 3644's experience of separating solar scattering off the line_14: nearby rings from the 37 Rayleighs signal 120000 away convinces us line_15: scattering from Jupiter at a distance of 671000 km will be much less line_16: severe. Dark count from the dectectors will be the leading noise term. ! question: 5 section: 1 line_1: The observations should take place between the time window of April 20 line_2: and May 10, 1994, constrained by maintenance of a small zenith angle in line_3: the dark Earth atmosphere. No Jovian satellites should be in the field line_4: of view of the detector during the exposure, since it the line_5: magnetospheric gas that is to be detected. ! question: 6 section: 1 line_1: No special calibration required. ! ! question: 8 section: 1 line_1: ! question: 9 section: 1 line_1: CYCLE-2 GO3644, with title, ``A Search for the Hydroxyl Radical in line_2: Saturn's Magnetosphere'' detected 37 Rayleigh emission in the OH line_3: A-X (0,0) band at 3085A. The current proposal is related to the earlier line_4: HST observation only in that the surprisingly large OH signal seen at line_5: Saturn prompted the consideration of the existance of OH at Europa. The line_6: source rate at Saturn for the production of OH was found to be 20 times line_7: larger than that predicted by ion sputtering of the icy satellites line_8: alone. If the production of OH was enhanced by an extraplanetary line_9: source, such as micrometeoritic erosion of the icy moon's surfaces, line_10: then such a mechanism may be likely at Jupiter as well, with Europa line_11: the likely candidate for observation of the effect. Otherwise, the line_12: program proposed here is independent of the previous observation. line_13: The successful detection of OH in Saturn's magnetosphere by GO3644 line_14: was the first remote detection of a molecular species in a planetary line_15: atmosphere. The observation has significant impact upon both line_16: theoretical and observational studies of the Saturn system. The line_17: detected brightness of 37 Rayleighs implied much larger quantities of line_18: neutral particles in the magnetosphere than had previously been line_19: inferred. The result does agree well with the prediction of Shemansky line_20: and Hall (1992) based upon their analysis of the magnetospheric energy line_21: budget and upon establishment of the distribution of atomic hydrogen line_22: by analysis of Voyager UVS observations of H Lyman-alpha emission. ! question: 9 section: 2 line_1: The results of the observations of GO3644 were published in: line_2: The Hydroxyl Radical in the Saturn Magnetosphere, D. E. Shemansky, line_3: P. L. Matheson, D. T. Hall, H-Y. Hu, and T. M. Tripp, in Nature, line_4: vol. 363, pages 329-331, 1993. line_5: Further analysis is in process and will appear in a more extensive line_6: article. ! question: 10 section: 1 line_1: Several SUN SparcStations, with substantial disk capacity are line_2: available at the University of Southern California at minimal cost to line_3: the department. Within our group, IRAF/STSDAS has been installed and line_4: is operational on one dedicated machine which also contains an line_5: extensive set of atomic and ion electronic model structures and line_6: accompanying analytical codes necessary to reduce complex spectra. line_7: This database and software collection has been developed over the line_8: past 15 years. The CPU time required to reduce and analyze the HST line_9: data associated with this research program are anticipated to have line_10: minimal impact on the current computing load. ! !end of general form text general_form_address: lname: SHEMANSKY fname: DONALD mi: E. category: PI inst: UNIV. OF SOUTHERN CALIFORNIA addr_1: DEPT. OF AEROSPACE ENGINEERING addr_2: UNIV. OF SOUTHERN CALIFORNIA city: LOS ANGELES state: CA zip: 90089 country: USA phone: 213-740-7184 telex: 4720490 USC LSA ! ! end of general_form_address records ! No fixed target records found solar_system_targets: targnum: 1 name_1: EURTOR descr_1: OFFSET JUPITER lev1_1: STD = JUPITER, ACQ=1.5 lev2_1: TYPE = TORUS, lev2_2: LONG = 90, lev2_3: LAT = 0, lev2_4: RAD = 6.6E+05, lev2_5: POLE_LAT = +90 wind_1: WND1 = 01-APR-94 TO 31-MAY-1994 wind_2: SEP OF EURTOR EUROPA FROM EARTH GT 10" wind_3: SEP OF EURTOR IO FROM EARTH GT 10" wind_4: SEP OF EURTOR CALLISTO wind_5: FROM EARTH GT 10" wind_6: SEP OF EURTOR GANYMEDE wind_7: FROM EARTH GT 10" comment_1: ESTIMATED BAND BRIGHTNESS 5 RAYLEIGHS comment_2: CONTINUUM IS SKY BACKGROUND comment_3: NO SATELLITES IN FIELD OF VIEW comment_4: SEP OF LOS EUROPA FROM EARTH GT 10 comment_5: SEP OF LOS IO FROM EARTH GT 10 comment_6: SEP OF LOS CALLISTO FROM EARTH GT 5 comment_7: SEP OF LOS GANYMEDE FROM EARTH GT 5 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 1.000 targname: EURTOR config: FOS/RD opmode: IMAGE aperture: 4.3 sp_element: G270H wavelength: 3090 num_exp: 1 time_per_exp: 64M s_to_n: 1 fluxnum_1: 2 priority: 3 param_1: Y-SIZE =1, param_2: COMB =YES, param_3: SUB-STEP =4 req_1: CYCLE 4; req_2: GUID TOL 0.2"; req_3: AT 1-AUG-94 +/- 7D; comment_1: SINGLE GUIDE STAR OK comment_2: BLIND POINTING ACQUISITION. comment_3: MERGE TO PRODUCE 4 APPROX comment_4: EQUAL LENGTH ALIGNMENTS. comment_5: EXPAND TO FILL 2 ORBITS. ! ! ! end of exposure logsheet ! No scan data records found