! 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