From: IN%"kent.tobiska@jpl.nasa.gov" "W. Kent Tobiska" 3-SEP-1998 17:34:31.28 To: IN%"lisa.c.crowell@jpl.nasa.gov" "Lisa Crowell" CC: IN%"kent.tobiska@jpl.nasa.gov" Subj: Orbit E17 UVS/EUV science objectives Return-path: Received: from eis-msg-014.jpl.nasa.gov by pisces.colorado.edu (PMDF V4.2-13 #26137) id <01J1DMCLKA5CHSIYTQ@pisces.colorado.edu>; Thu, 3 Sep 1998 17:33:37 GMT Received: from [137.78.240.45] (karakh.jpl.nasa.gov [137.78.240.45]) by eis-msg-014.jpl.nasa.gov (8.8.5/8.8.5) with ESMTP id KAA29916; Thu, 3 Sep 1998 10:32:50 -0700 (PDT) Date: Thu, 03 Sep 1998 10:40:37 -0700 From: "W. Kent Tobiska" Subject: Orbit E17 UVS/EUV science objectives To: Lisa Crowell Cc: kent.tobiska@jpl.nasa.gov Message-id: MIME-version: 1.0 Content-type: text/enriched; charset="iso-8859-1" Content-transfer-encoding: quoted-printable X-Sender: ktobiska@pop.jpl.nasa.gov Hi Lisa, Here is a summary for the orbit E17 UVS/EUV science objectives. Europa: 1) Look for Europa atmospheric emissions (oxygen, hydrogen and sulfur, as well as other possibilities) on the body and at -1, +1 and +2 radii off body or at -2, +2 and +3 radii off body; this will be done with 1304, 1356, 1479, and 1216 =C5 mini-scans and full G/G scans. We will also monitor the tenuous atmosphere for possible outgassing episodes. (17EUATMOS_01-, 17EUATMOS_02-). 2) Observe Europa's surface at various longitudes and phase angles to get good signal using F/F full scans. These observations will complement the nominal mission observations to derive phase curves for several locations on Europa and to understand how exogenic processes affect the surface scattering. We are interested in obtaining a high signal-to-noise at the shorter wavelengths (<< 2200 =C5) to see if Europa's surface has any distinctive features in this region. (17EUSURFAC01-, 17EUSURFAC02-). 3) Ride-along with NIMS to observe a particular feature or region on Europa at phase angles not obtainable from the Earth using full F/F scans in the 1600=C5 to 3200=C5 wavelength region. Data will supplement and complement the NIMS surface property measurements. (17EUEUR20H01+, 17EUGLOBAL01+, 17EUGLOBAL02+, 17EUSUCOMP01+, 17EUSUCOMP02+, 17EUSUCOMP03+, 17EUSUCOMP04+). Io: 1) UVS observations of Io have been very successful in identifying regions of relatively thick sulfur dioxide gas associated with volcanic plumes, both those detected by SSI and probable "stealth plumes". These thick regions have been identified by a distinctive feature in the UVS spectral range which has not previously been used by HST; our observation will greatly enhance our understanding of Io's volcanoes and atmosphere. The E17 orbit presents an excellent opportunity to observe the Pele region since the UVS will not participate in the I24 observation due to the high radiation environment during those close-up observations. Lat/lon =3D 0/255. (17IUPELEPLM1-). 2) Real-time EUV map of Io torus midnight ansa. 24 EUV sectors (part of an annulus at 90 deg cone) centered on wobbling torus. EUV on, by agreement with HIC, between the time 90 deg cone crosses Jupiter (0 Rj) and the ansa of Europa's orbit (9 Rj), catching the UV-bright ansa ribbon at 5.76 Rj. Spacecraft distance from Jupiter is at least 17 Rj. EUV spectrum is 540 to 1280 =C5, including torus emission lines at 685 (S++), 765 (S+), and 834 (O+) =C5. In conjuction with UVS observation centered on torus ansa ribbon. (17TV17MANS01-). 3) Real-time UVS map of Io torus midnight ansa. Targeted once to 90 deg cone; clock angle selected to center observation on wobbling torus (clock drifts at 1-2 deg/hr with playback started and Scan-Type 3 in effect). UVS high voltage on between the time 90 deg cone crosses Jupiter (0 Rj) and the ansa of Europa's orbit (9 Rj), catching the UV-bright ansa ribbon at 5.76 Rj. Spacecraft distance from Jupiter is at least 17 Rj. UVS G- and N-channel (1132 to 1920, and 2820 to 4320 =C5) miniscans are used to observe torus emission lines from 1240 to 1272 =C5 (S++ at 1259), and from 4041 to 4099 =C5 (S+ at 4070). In conjuction with longer-duration EUV observation centered on torus ansa ribbon. (17TU17MANS01-).=09 Jupiter: 1) Southern Jupiter aurora observations of Lyman-alpha and H2 emissions above cone 82 near the 80 degree longitude. We will attempt to capture the Io fluxtube footprint (IFT) and any fluxtube that maps from Europa to Jupiter to understand long-term magnetosphere and Jovian upper atmosphere interaction. This is a realtime observation for 1.5 hours using F/G full-scans at a distance from Jupiter >15 Rj. (17JUAURORA_S-) 2) AWG feature campaign recovering E16 lost observations to study the role and abundance of water, aerosols, and dynamics in Jupiter's atmosphere surrounding white ovals. This is a realtime observation using a full F/F scan at a distance from Jupiter =3D 14.7 Rj. Visible images by SSI 3x1 mosaic (17JSWTOVAL01). Oval lat/lon=3D-33/350-357 planetographic. (17JUFEATUR01-, 17JUFEATUR02-). =09 ************************** W. Kent Tobiska FDC/JPL, MS 264-580=20 4800 Oak Grove Dr. Pasadena, CA 91109 (818) 393-7742 (phone) (818) 393-4530 (fax) kent.tobiska@jpl.nasa.gov **************************