!   $Id: 5376,v 9.1 1994/07/27 17:16:15 pepsa Exp $

coverpage:

  title_1:         A SEARCH FOR A MOLECULAR OXYGEN ATMOSPHERE ON EUROPA: CYCLE4 MEDIUM
    sci_cat:       SOLAR SYSTEM
    sci_subcat:    SATELLITES
    proposal_for:  GO
    pi_fname:      DOYLE
    pi_mi:         T.
    pi_lname:      HALL
    pi_inst:       2380
    pi_country:    USA
    pi_phone:      410-516-8784
    hours_pri:     2.52
    num_pri:       1
    hrs:           Y
    off_fname:     CHERYL-LEE
    off_lname:     HOWARD
    off_title:     ASSISTANT DEAN
    off_inst:      2380
    off_addr_1:    THE JOHNS HOPKINS UNIVERSITY
    off_addr_2:    HOMEWOOD RESEARCH ADMINISTRATION
    off_addr_3:    105 AMES HALL
    off_city:      BALTIMORE
    off_state:     MD
    off_zip:       21218
    off_country:   USA
    off_phone:     410-516-8668
! end of coverpage

abstract:

    line_1:        We will use the HST GHRS to search for a molecular oxygen (O2)
    line_2:        atmosphere on Jupiter's satellite Europa.  The Voyager spacecraft
    line_3:        revealed much about Europa's surface characteristics, but failed
    line_4:        to perform occultation or airglow observations necessary to constrain
    line_5:        its atmosphere.  There is observable evidence of energetic particle
    line_6:        sputtering on Europa's icy surface, and the sputtered water fragments
    line_7:        are thought to reassociate to form molecular hydrogen and oxygen.
    line_8:        The oxygen molecules are gravitationally bound to the satellite
    line_9:        and could accumulate into a detectable O2 atmosphere.  Europa lies in
    line_10:       the outer regions of the Io plasma torus, and is subjected to a
    line_11:       significant electron flux.  If Europa has a tenuous O2 atmosphere,
    line_12:       dissociative electron impact excitation would produce significant
    line_13:       OI 1356A emission.  We will search for this emission using
    line_14:       the HST GHRS.  The observation will provide the most stringent
    line_15:       observational limit on Europa's atmosphere to date,
    line_16:       improving the current upper limit by almost two orders of magnitude.
    line_17:       Detecting an oxygen atmosphere on Europa would be a significant
    line_18:       accomplishment for HST, and would provide invaluable information to
    line_19:       use in planning the upcoming Galileo spacecraft encounter with the
    line_20:       Jupiter system.

!
! end of abstract

general_form_proposers:

  lname:           HALL
    fname:         DOYLE
    mi:            T.
    inst:          2380
    country:       USA

!

  lname:           FELDMAN
    fname:         PAUL
    mi:            D.
    inst:          2380
    country:       USA

!

  lname:           MCGRATH
    fname:         MELISSA
    mi:            A.
    inst:          3470
    country:       USA

!

  lname:           MOOS
    fname:         H. WARREN
    inst:          2380
    country:       USA

!

  lname:           STROBEL
    fname:         DARRELL
    mi:            F.
    inst:          2380
    country:       USA

!

  lname:           WEAVER
    fname:         HAROLD
    mi:            A.
    inst:          3470
    country:       USA

!
! end of general_form_proposers block

general_form_text:

  question:        3
    section:       1
    line_1:        One dark-time observation of Europa using the LSA of the HRS centered
    line_2:        on wavelength 1356A is requested.  If GHRS side 1 is repaired
    line_3:        during the HST servicing mission, the grating G140L is requested;
    line_4:        otherwise use G160M.  Orbital dark-time is required to minimize Earth
    line_5:        OI 1356A airglow.

!

  question:        4
    section:       1
    line_1:        The major objective of this program is to fill in a significant
    line_2:        gap left over from the Voyager spacecraft mission: neither Voyager
    line_3:        encounter with the Jupiter system provided occultation or airglow
    line_4:        measurements to constrain the extent of Europa's atmosphere.
    line_5:        Ground-based observations are not feasible because of Earth's
    line_6:        pervasive oxygen airglow. Finally, HST is the only operating
    line_7:        spacecraft capable of performing the Europa OI 1356A observation.
    line_8:        Using the IUE satellite requires prohibitively long exposure times.

!

  question:        5
    section:       1
    line_1:        Orbital dark-time is required to minimize terrestrial OI 1356A
    line_2:        contamination.  The observation is designed to detect 200 Rayleighs
    line_3:        of emission from Europa in the OI 1356A doublet.  From HST's altitude,
    line_4:        observed upward-looking day-time Earth airglow intensities are
    line_5:        competitive with this.  Orbital dark-time is required to obtain
    line_6:        an unambiguous detection, and maximize the signal-to-noise with
    line_7:        minimum spacecraft time usage.

!

  question:        6
    section:       1
    line_1:

!


!

  question:        8
    section:       1
    line_1:

!

  question:        9
    section:       1
    line_1:        ID# 2442: Cometary Parent Molecules, Feldman PI (not related)
    line_2:        ID# 2481: HST Observations of Periodic Comets, Feldman CoI (not rel)
    line_3:        ID# 2483: The Volatile Composition of New Comets, Feldman CoI (not rel)
    line_4:        ID# 2625: Excitation Processes for Outer Planet UV Emission, Moos PI;
    line_5:        McGrath, Strobel CoIs (not rel)
    line_6:        ID# 2627: Io's Atmosphere and its Interaction with the Plasma Torus,
    line_7:        Moos, PI; Feldman, Mcgrath, Strobel CoIs (not rel)
    line_8:        ID# 3064: HST Observations of Comet Levy (1990c), Feldman CoI (not rel)
    line_9:        ID# 3482: The Nature of the Variable Infalling Matter on the Star Beta
    line_10:       Pictoris, Feldman, Moos, CoIs (not rel)
    line_11:       ID# 3617: The UV Emissions of Titan, McGrath PI; Feldman, Moos, Strobel
    line_12:       CoIs (not rel)
    line_13:       ID# 3618: Excitation Processes for Outer Planet UV Emission - Cycle 2
    line_14:       Cont. of #2625, Moos PI; Feldman,McGrath,Strobel CoIs (not rel)
    line_15:       ID# 3644: A Search for the Hydroxy Radical in Saturn's Magnetosphere,
    line_16:       Shemansky PI; Hall CoI (not rel)
    line_17:       ID# 3707: HST Observations of Periodic Comets, Feldman CoI (not rel)
    line_18:       ID# 4513: Volatile Composition of New Comets, Feldman CoI (not rel)
    line_19:       ID# 4349: Composition of Comet Enke, Feldman CoI (not rel)
    line_20:       ID# 4545: Outgassing from Ceres, Feldman CoI (not rel)

!

  question:        10
    section:       1
    line_1:        The Johns Hopkins University provides partial salary support of the
    line_2:        P.I., 80% of graduate student tuition fees, and contributes to the
    line_3:        maintenance of the computers and network facilities used in this
    line_4:        program. Similar support is provided by the other co-I institutions.

!
!end of general form text

general_form_address:

  lname:           HALL
    fname:         DOYLE
    mi:            T.
    category:      PI
    inst:          2380
    addr_1:        THE JOHNS HOPKINS UNIVERSITY
    addr_2:        CENTER FOR ASTROPHYSICAL SCI.
    addr_3:        CHARLES AND 34TH STREETS
    city:          BALTIMORE
    state:         MD
    zip:           21218
    country:       USA
    phone:         410-516-8784
    telex:         dthall@pha.jhu.edu

!
! end of general_form_address records

! No fixed target records found

solar_system_targets:

  targnum:         1
    name_1:        EUROPA
    descr_1:       SATELLITE EUROPA
    lev1_1:        STD = JUPITER
    lev2_1:        STD = EUROPA
    wind_1:        SEP OF EUROPA JUPITER FROM EARTH GT 15"
    wind_2:        OLG OF EUROPA FROM SUN BETWEEN 225 315
    comment_1:     OBSERVE EUROPA WHEN SEPARATED FROM
    comment_2:     JUPITER BY MORE THAN 15 ARCSEC. AT 5AU,
    comment_3:     EUROPA'S RADIUS OF 1569 KM PROJECTS AN
    comment_4:     ANGLE OF 0.43 ARCSEC. ASSUMING AN
    comment_5:     EMITTING ATOMIC OXYGEN GAS T = 150 K,
    comment_6:     THE INTRINSIC WIDTH OF EACH LINE IN THE
    comment_7:     DOUBLET IS 1.8 MA.  THE OBSERVATION IS
    comment_8:     DESIGNED TO DETECT 200 R IN THE DOUBLET
    comment_9:     OR 158 R IN THE 1355.6 A LINE, OR
    comment_10:    2.4 E-12 ERG CM-2 S-1 A-1 ARCSEC-2.
    fluxnum_1:     1
    fluxval_1:     V = 5.3
    fluxnum_2:     2
    fluxval_2:     SURF-LINE(1355.6) = 2.4 E-12
    fluxnum_3:     3
    fluxval_3:     W-LINE(1355.6) = 1.8 E-03
    fluxnum_4:     4
    fluxval_4:     SIZE = 0.43

!
! end of solar system targets

! No generic target records found

exposure_logsheet:

    linenum:       1.000
    targname:      EUROPA
    config:        HRS
    opmode:        ACQ
    aperture:      2.0
    sp_element:    MIRROR-N2
    num_exp:       1
    time_per_exp:  1.44S
    fluxnum_1:     1
    priority:      1
    param_1:       BRIGHT=RETURN
    req_1:         CYCLE 4;
    req_2:         ONBOARD ACQ FOR 2.0;
    req_3:         COND IF HRS SIDE 1 AVAILABLE /4.0-6.0;
    req_4:         SELECT 1 OF 1.0-3.0 OR 4.0-6.0;
    comment_1:     STEP-TIME = 0.16 S;
    comment_2:     EXPECT 10,000 COUNTS IN STEP-TIME;
    comment_3:     EXPOSURES 1.0-3.0 TO BE DONE
    comment_4:     IF GHRS SIDE 1 IS INOPERATIVE

!

    linenum:       2.000
    targname:      EUROPA
    config:        HRS
    opmode:        ACQ/PEAKUP
    aperture:      2.0
    sp_element:    MIRROR-N2
    num_exp:       1
    time_per_exp:  16.32S
    fluxnum_1:     1
    priority:      1
    req_1:         CYCLE 4;
    req_2:         ONBOARD ACQ FOR 3.0;
    comment_1:     STEP-TIME = 0.16 S;
    comment_2:     EXPECT 10,000 COUNTS IN STEP-TIME;
    comment_3:     EXPOSURES 1.0-3.0 TO BE DONE
    comment_4:     IF GHRS SIDE 1 IS INOPERATIVE

!

    linenum:       3.000
    targname:      EUROPA
    config:        HRS
    opmode:        ACCUM
    aperture:      2.0
    sp_element:    G160M
    wavelength:    1356
    num_exp:       1
    time_per_exp:  123M
    s_to_n:        4.4
    fluxnum_1:     2
    fluxnum_2:     3
    fluxnum_3:     4
    priority:      1
    param_1:       FP-SPLIT = STD,
    param_2:       STEP-PATT = 5
    req_1:         CYCLE 4;
    req_2:         DARK TIME;
    comment_1:     EXPOSURES 1.0-3.0 TO BE DONE
    comment_2:     IF GHRS SIDE 1 IS INOPERATIVE

!

    linenum:       4.000
    targname:      EUROPA
    config:        HRS
    opmode:        ACQ
    aperture:      2.0
    sp_element:    MIRROR-N2
    num_exp:       1
    time_per_exp:  1.44S
    fluxnum_1:     1
    priority:      1
    param_1:       BRIGHT=RETURN
    req_1:         CYCLE 4;
    req_2:         ONBOARD ACQ FOR 5.0;
    comment_1:     STEP-TIME = 0.16 S;
    comment_2:     EXPECT 10,000 COUNTS IN STEP-TIME;
    comment_3:     EXPOSURES 4.0-6.0 TO BE DONE
    comment_4:     IF GHRS SIDE 1 IS OPERATIVE

!

    linenum:       5.000
    targname:      EUROPA
    config:        HRS
    opmode:        ACQ/PEAKUP
    aperture:      2.0
    sp_element:    MIRROR-N2
    num_exp:       1
    time_per_exp:  16.32S
    fluxnum_1:     1
    priority:      1
    req_1:         CYCLE 4;
    req_2:         ONBOARD ACQ FOR 6.0;
    comment_1:     STEP-TIME = 0.16 S;
    comment_2:     EXPECT 10,000 COUNTS IN STEP-TIME;
    comment_3:     EXPOSURES 4.0-6.0 TO BE DONE
    comment_4:     IF GHRS SIDE 1 IS OPERATIVE

!

    linenum:       6.000
    targname:      EUROPA
    config:        HRS
    opmode:        ACCUM
    aperture:      2.0
    sp_element:    G140L
    wavelength:    1356
    num_exp:       1
    time_per_exp:  123M
    s_to_n:        9.8
    fluxnum_1:     2
    fluxnum_2:     3
    fluxnum_3:     4
    priority:      1
    param_1:       FP-SPLIT = STD,
    param_2:       STEP-PATT = 5
    req_1:         CYCLE 4;
    req_2:         DARK TIME;
    comment_1:     EXPOSURES 4.0-6.0 TO BE DONE
    comment_2:     IF GHRS SIDE 1 IS OPERATIVE

!
! end of exposure logsheet

! No scan data records found