From: IN%"KTOBISKA@gllsvc.jpl.nasa.gov" 25-AUG-1997 17:28:49.16 To: IN%"SIMMONS@pisces.colorado.edu" Subj: C9 UVS/EUV OAP text Subject: C9 UVS/EUV OAP text From: Stuart Stephens Date: 6/16/97 9:51 AM C9 UVS/EUV Science Overviews AWG The highest priority UVS Jupiter atmospheric observations during C9 are a set of real-time far- and mid-ultra-violet (FUV and MUV, UVS G and F channels, 115-320 nm), high solar phase angle (70 deg) observations of the GRS trailing vortices (FTKR2Exx). Combined with this is a set of FUV plume observations 1/2 rotation earlier, also at high solar phase angle (80 deg) (FTKR1Exx). There will be two additional high solar phase angle observations (157 and 140 deg) obtained in the FUV/MUV as ridealong observations (FTK15701 and FTK14001) with SSI during two science turns inbound to C10. Analysis of the data will result in a unique data set of stratospheric aerosol scattering properties at high solar phase angles and two emission angles, simultaneous with SSI two-color images. In FTK15701 we also obtain dark-limb ring data in the MUV as a ridealong with NIMS. Real-time global mapping of equatorial H Lyman-alpha on the Jupiter darkside (DRKMAP) will continue as in previous orbits, to obtain hydrogen distribution maps without the effect of direct solar radiation. Southern aurora will be mapped from 260 to 360 deg longitude; H2 band color ratios will be observed to determine precipitating particle energies (AURMAP01-02). Northern aurora will be mapped on the dayside at 170 deg longitude with a similar objective (FIXLON). Of unique importance are two outbound auroral observations. AURMAP04 observes southern dusk aurora with objectives similar to AURMAP01-02. AURVAR is coincident with the Fields and Particles Campaign A observation and will record southern aurora short time-scale variability as well as spatial characteristics of the Io fluxtube footprint at H Lyman-alpha wavelengths. There will also be the second of two UVS star calibration in the mission during the cruise portion of the orbit on the same star as viewed during G1 (Delta Scorpii). MWG The highest priority UVS magnetospheric observation during C9 is a set of real-time Io torus midnight ansa measurements performed outbound from Jupiter C/A, in conjunction with EUV, when both are pointed at 90 deg cone angle. This C9MANS04 observation is designed to obtain S and O ion emission line strengths at EUV as well as FUV and NUV (UVS N channel, 280-430 nm) wavelengths. Ratios of intensities will determine electron temperatures, and the integrated intensity characterizes the torus energy output for energy budget considerations. Although not simultaneous with EUV, two sets of real- time FUV and NUV torus ansa observations are also a high priority during C9. C9MPROxx (inbound at >90 deg cone angle) and C9NANSxx (outbound, at 90 deg) are torus ansa profiles obtained while the UVS drifts over the midnight and noon ansa ribbons, respectively. Two independent real-time EUV observations also occur after the instrument is turned on 19 Rj outbound from Jupiter C/A, an aurora map (C9AURA) and a map of the extension of the Io torus midnight ansa beyond Europa's orbit (C9FANS). UVS will also observe the midnight ansa of Callisto and Ganymede's orbits (CTORUS and GTORUS) in C9. These observations are intended to search for FUV emissions from H, O, and S in hypothetical neutral clouds in the vicinity of each satellite, and will be made at <90 deg cone angle. Finally, a set of seventeen UVS magnetonebula observations are planned during the cruise portions of C9. Six of these MAGNEB observations will be long-duration measurements (18 days total) of FUV emissions looking along the axis of the magnetonebula in the spacecraft antisun direction, and eleven will be 3-hour observations designed to monitor the performance of the UVS grating. SWG The UVS Galilean satellite observations during C9 include four high- resolution observations of Ganymede in the MUV (160-320 nm), and one MUV Ganymede phase angle observation at low resolution at a solar phase angle not obtainable from Earth. The four high-resolution observations are recorded ridealongs with NIMS and are designed to supplement and complement NIMS surface property measurements. In addition to two GLOBAL views, DRKLIT observes the transition between dark and light material in Galileo Regio, and BRILED observes the bright endmember on the leading hemisphere. The other Ganymede observation is an independent real-time UVS view, PHAS78 at 78 deg solar phase angle. It will be used with complementary observations obtained in other orbits to measure satellite albedos and emissions at different phase angles. In addition, a set of seven MUV Callisto observations will be obtained during the targeted satellite encounter in C9. Most are recorded NIMS ridealongs in the MUV: ANARR and SKULD view high-albedo craters, NOLAT obtains northern latitude coverage, VALHAL and VALSPC observe Valhalla's palimpsest and ring structure, and there is one GLOBAL view of Callisto. A seventh recorded Callisto observation is an independent UVS measurement in the FUV of volatile distribution with altitude off the bright limb of the satellite. Five real-time MUV Europa observations are planned in C9, PHAS81, 77, 05, and 03 at solar phase angles from 81 to 3 deg, plus one eclipse observation, DARK. A set of four real-time Io eclipse full-spectral (FUV/MUV) observations (IECLPS) also occur in C9. Comparison with eclipse ingress and egress observations from other orbits will provide the morphology of Io's atmosphere in the presence and absence of direct sunlight. Finally, there is a real-time Io neutral cloud (NTRLCL) observation.