From spencer Mon Feb 5 14:03:45 1996 From spencer Mon Feb 5 14:03:45 1996 To: oleroemer Subject: Ole Roemer Messenger Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Content-MD5: EM0/4WroNKxetSmZHLrqfQ== Status: RO X-Lines: 702 Content-Type: text/plain; charset="us-ascii" Content-Length: 33316 __________________________________________________________________________ T H E O L E R O E M E R M E S S E N G E R _______________________________________________ JJJJ C G JJJJJJ I E JJJJ __________________________________________________________________________ Newsletter of the International Jupiter Watch Satellite Discipline Issue 19 February 5th, 1996 Editor and Discipline Leader: John Spencer Voice: (520) 774-3358 Lowell Observatory Fax: (520) 774-6296 1400 W. Mars Hill Rd. (Note the new telephone area code) Flagstaff, AZ 86001 Internet: spencer@lowell.edu FTP site: ftp.lowell.edu, directory pub/ijw WWW site: http://www.lowell.edu/users/ijw/ijwhome.html E-mail exploder address (use with discretion!): oleroemer@lowell.edu ___________________________________________________________________________ CONTENTS 1) Jupiter in 1996 2) Improved Web site 3) Io activity update: Another outburst in 1995 4) IRTF Galileo support Io monitoring 5) 1996 observing plans: Groundbased 6) 1996 observing plans: HST 7) 1996 observing plans: IUE 8) Galileo update 9) Galilean satellite special session at Spring AGU 10) Laboratory Planetology Symposium at COSPAR (belated announcement) 11) IJW-related sessions at the Western Pacific Geophysics Meeting 12) Post-Galileo Io workshop: postponed 13) Publications in the pipeline ___________________________________________________________________________ 1) JUPITER IN 1996 Next Jupiter opposition is on July 4 1996. 1996 Galileo perijove passes, which will allow medium-resolution Io observations and high-resolution observations of the named satellites, occur as follows: G1: June 27 1996 (Ganymede targeted) G2: Sept. 7 1996 (Ganymede targeted) C3: Nov. 6 1996 (Callisto targeted, Europa untargeted, best Io in tour) E4: Dec. 19 1996 (Europa targeted) ___________________________________________________________________________ 2) IMPROVED WEB SITE The IJW Satellites Discipline Web site (http://www.lowell.edu/users/ijw/ijwhome.html) has now been significantly expanded and improved. It now features: 1) A cumulative list of known volcanic events (and non-events) on Io, starting in February 1995. 2) A bibliography of Jovian satellite publications. 3) A description of, and images from, the IRTF Galileo support Io monitoring program. 4) A link to the Galileo project web page that contains graphical illustrations of all Galileo remote sensing observations. 5) Other items that seemed like a good idea at the time. Eventually we may want to put all information on the Web site rather than in e-mail messages, and simply send out e-mail notifications when new items appear on the Web site. Any comments on this idea? Please send me suggestions for additional information or links to include. One thing that would be very nice, suggested by Tony Mallama, would be an interactive Jovian satellite ephemeris, like the impressive Saturn satellite ephemeris site put together by Mark Showalter (http://ringside.arc.nasa.gov/www/rpx/rpx.html). Would anyone be interested in creating something like this for us? ___________________________________________________________________________ 3) IO ACTIVITY UPDATE: ANOTHER OUTBURST IN 1995 Known volcanic events on Io, starting in early 1995, are now summarised on the IJW Satellites web site. I'll try to keep the summary there up-to-date. Some new but belated news: The IRTF Galileo Support Jupiter/Io Monitoring program detected a major outburst on Io on 95/09/27, possibly at the same site as the 95/03/02 outburst reported previously (45 S, 95 W, +/- 15 degrees): the first evidence for a "repeater" outburst site. Neither I nor, apparently, anyone else had looked at that night's images, so the event was undetected till now. A 9/27 outburst image, and other results from the monitoring program, can be seen at "http://www.lowell.edu/users/ijw/irtfmon.html". A summary of recent "Io Volcano News" messages: Our last good look at Io before the December 7th 1995 Galileo encounter was on November 12th, 1995, when Christophe Dumas observed an occultation and eclipse of Io by Jupiter with NSFCAM at the IRTF. Loki was then experiencing one of its recurring periods of high activity, continuing an eruption that probably started in late August, but other recently-bright hot spots on the Jupiter-facing hemisphere had faded. Spencer, Goguen, Orton, Hoffmann, Yanamandra-Fisher, Stewart, Golisch, etc. obtained 8.8, 12.5, and 20 micron unresolved imaging of Io at various points in its orbit during the week of the Galileo encounter, with MIRAC at the IRTF. Reduction of the images by John Stansberry and Jay Goguen shows (a) it's very difficult to do good photometry through a plastic sunshade 8 degrees from the sun, and (b) the trailing hemisphere of Io was brighter than the leading hemisphere, consistent with activity at Io, but we can't yet tell if the activity was closer to the high or low end of the normal range at encounter time, so we don't know if the August-November Loki brightening continued till the encounter. The first observations of Io after solar conjunction were taken on January 23rd 1996, when Howell, Klebe, Creech-Eakman, and Dahn at WIRO (Wyoming) with the "TNT" mid-infrared camera. Io was observed in eclipse at 10, 11, and 18 microns, and preliminary photometry showed that the 11 micron eclipse flux appeared to be within the "normal range". ___________________________________________________________________________ 4) IRTF GALILEO SUPPORT IO MONITORING Due to the the lack of Io remote sensing data from the December 1996 Galileo encounter, the Galileo support Io monitoring program at the IRTF will not resume in earnest until mid-May, but will then (hopefully) continue throughout the Galileo orbital tour. More details on the program, and some sample images, can be found at "http://www.lowell.edu/users/ijw/irtfmon.html", and the raw images are publicly available at ftp.irtf.ifa.hawaii.edu, directory pub/galileo. ___________________________________________________________________________ 5) 1996 OBSERVING PLANS: GROUNDBASED IO VOLCANO MONITORING: Observers Facility Instrument UT Dates Purpose ----------------------------------------------------------------------- Spencer, IRTF, NSFCAM 2/06;2/14;2/16; Eclipses and occultations Stansberry, Mauna 1-5 mic 2/29;3/02;3/23; by Jupiter, 1.7-5.0 microns Dumas Kea camera 4/08;4/24;4/26; Locations and variability 6/02;6/27(?); of individual hot spots. 7/04;7/06(?) August onwards unscheduled Goguen, IRTF, Bolo- 5/23-5/26; IR lightcurves, 5-20 Matson,Veeder, Mauna meter 6/25-6/30(?) microns. Longitudinal Blaney, Kea August onwards distribution and variability Johnson unscheduled of hot spots, heat flow. Goguen et al. Palomar MIRLIN 4/21-4/25; Disk-resolved 4.8-12.5 micron 5-meter IR camera 4 partial nights imaging of Io. Mid-August Goguen et al. Palomar Spectro- 4 partial nights Disk-resolved 4.8-12.5 micron 5-meter cam 10 late June- imaging of Io. IR camera early July Howell WIRO, Speckle ?? 3-5 micron eclipses and Wyoming system occultations by Jupiter, 5 micron lightcurves, bright hot spot locations. Howell, WIRO, TNT 10 1/23,?? 10-18 micron sunlit, Creech-Eakman, Wyoming micron eclipse photometry. Heat Dahn, Klebe, camera flow, variability Spencer, Lowell/ OSIRIS 3/02;3/09; Eclipses and occultations Stansberry OSU 72" 1-2.5 April onwards by Jupiter, 1.7-2.3 microns. Flag- mic unscheduled Locations and variability of staff camera individual hot spots. OTHER PROGRAMS THAT I KNOW ABOUT Observers Facility Instrument UT Dates Purpose ----------------------------------------------------------------------------- Bell, Veverka, IRTF, NSFCAM, 7/25-7/26 Images and spectra of Brown, Mauna CoCo Amalthea, Thebe Cruikshank Kea Coronograph (see below) Monet, Owen, USNO, 2048 Frequent Improve Galilean satellite et al. Flag- CCD ephemerides (see below) staff ------------------------------------ Bill Owen of JPL (wmo@wansor.jpl.nasa.gov) gives more details on the JPL/USNO astrometric program: For the fifth year, the U.S. Naval Observatory Flagstaff Station, under contract to JPL, will observe the Galilean satellites for astrometry purposes. These observations, taken at the 61-inch telescope with a Tektronix 2048 CCD (11-arcminute field), consist of repeated short exposures alternating with partial readout of the chip. This technique can store dozens of observations in the equivalent of 11 image files. Since the Galileo orbiter has yet to take its first in situ optical navigation frame, groundbased astrometry is becoming increasingly important. The observations at Flagstaff, when combined with Dan Pascu's photographic series in Washington, four centuries of eclipse timings, and other astrometry, provided a sufficiently up-to-date ephemeris to allow the events of last December to happen without opnav data. This observing program was described in poster paper 74.03, "Ground-based CCD Astrometry for the Galileo Mission," presented by Alice Monet at the just- concluded AAS meeting in San Antonio. Alice is our point of contact at NOFS, but many of their staff astronomers have assisted with the observations. I've been supplementing the Flagstaff observations with similar ones, but of lower quality, taken at JPL's 24-inch telescope at Table Mountain Observatory. -- Bill Owen -------------------------------------- And Jim Bell (jimbo@cuspif.tn.cornell.edu) gives more details on the small satellite IRTF observations: Jim Bell, Joe Veverka (Cornell), Bob Brown (JPL), and Dale Cruikshank (Ames) plan to use the IRTF NSFCAM and JPL's CoCo (Cooled Coronagraph) instruments to obtain H, K, and possibly L images and spectra of Jupiter's inner satellites Amalthea and Thebe. The observations are scheduled for July 25 and 26 UT. The goals are to constrain the surface composition and mineralogy of these objects and to search for evidence of hemispherical asymmetries. The observations will also provide calibration/validation assistance should Galileo NIMS be able to observe these objects from orbit. We are also interested in collaborating with other observers to obtain simultaneous UBVRIJ during the times of our near-IR observations. ___________________________________________________________________________ 6) 1996 OBSERVING PLANS: HST Spencer, McGrath, and McEwen have one orbit of Director's Discretionary HST time devoted to multispectral imaging of the new bright spot at Ra Patera, on Io, sometime between February 26th and March 10th. Observations of the volcanic activity in that period will be especially useful. Here's a list of approved Cycle 6 (July 1996-June 1997) HST observing programs devoted to the satellites of Jupiter, (or to other giant planet satellites): PI Institution Title -------------------------------------------------------------------------------- Ballester University of Michigan HST observations of Io's atmosphere coordinated with GALILEO Brown Caltech Determining the Crustal Composition of Io through Atmospheric Spectroscopy Denk Deutsche Forsch. fuer Luft- Disk-resolved Spectrophotometry of the und Raumfahrt Dark Side of Iapetus Goguen Jet Propulsion Laboratory Global Mapping of the Opposition Surge on the Galilean Satellites Hall The Johns Hopkins University Transit Observations of Io's Atmosphere Hall The Johns Hopkins University Far-UV Airglow and Albedo Observations of Europa and Ganymede McGrath STScI Io's SO2 Atmosphere: Patchy or Not? Noll STScI Ultraviolet Spectra of Saturn's Satellites: Ion Modification of Surface Ice Noll STScI The Ultraviolet Spectrum of Callisto Roush San Francisco State U. Ultraviolet Spectra of Uranian Satellites Seidelmann United States Naval Obs. Recovery of Inner Satellites of Neptune Spencer Lowell Observatory Temporal Variability of Io's Surface and Plumes Zellner Georgia Southern University Spectrophotometry of Inner Jovian Satellites Mike Brown (mbrown@kepler.gps.caltech.edu) supplies this additional information on his planned HST program "Determining the Crustal Composition of Io...": I've got an HST program for Cycle 6 (with Melissa McGrath) to look for silcon, magnesium, and Mg+ in the atmosphere of Io with the FOS (so it >has< to schedule sometime in the next year) around 2800 A. Sensitivities are good, so if there is a reasonable amount of silicon or magnesium relative to sodium, we should see it easily. But who knows what's really reasonable on Io.... John Spencer gives the following info. on his Cycle 6 Io imaging program, which is with McGrath, McEwen, Nash, Sartoretti, Clark, Ballester, and Trauger: We will obtain global longitudinal WFPC2 imaging of Io at 2500 A, 3400 A, and 4100 A on two occasions, in Summer 1996 and Spring 1997, to extend Galileo imaging coverage into the ultraviolet. We hope to look for the Loki and Pele plumes at 2500 A, following up on a very tentative identification of the Pele plume in 1995 HST images at this wavelength. Jay Goguen gives the following info on his Cycle 6 "Global Mapping of the Opposition Surge..." program: Dates not yet determined - 12 orbits in Cycle 6 for "Global Mapping of the Opposition Surge on the Galilean Satellites" (Some observations at phase angles less than 1 degree in early July a high priority). ___________________________________________________________________________ 7) 1996 OBSERVING PLANS: IUE Tim Livengood (tim.livengood@gsfc.nasa.gov) writes: Renee Prange and I are heading the IUE effort to observe UV emissions from the Jovian system for 30 days in August-September 1996 (exact dates not yet determined by the IUE Project). Within this period we are currently planning two sessions of observing Io through each elongation, with the periods separated by about a week. Thus: in session 1, we'll observe through one elongation, take a break for transit, then observe through the opposite elongation; and in session 2, we'll do something similar. Most of the detailed planning is still up in the air. [Particularly thorough monitoring of the volcanic activity during this period would probably be useful- Ed.] Deborah Domingue (domingue@lpi.jsc.nasa.gov), gives the following information: Lonne Lane and I have been alotted 100 hrs on IUE for this observing cycle. We've requested time in April, but haven't been scheduled just yet. I'm still waiting to hear back from them on the details. ___________________________________________________________________________ 8) GALILEO UPDATE Alas, the high-gain antenna didn't pop open during the orbit insertion burn... Galileo is now well into its first orbit, and is approaching apojove, where it will execute the Perijove Raise burn in mid-March. The tape recorder is still having problems, with the tape sometimes sticking to the read/write heads, but there appear to be workarounds, which include not using the first and last bits of the tape, and being careful about when and how the tape is stopped and started. The net result is a loss of about 20% of the tape capacity and the need for some redesign of observing sequences that would have generated "dangerous" sequences of tape usage. This means a lot of work for the sequence design teams, but fairly minimal loss of total science. About 60 CCD images of Jupiter and its satellites are planned during the first "G1" encounter, in late June 1996. Gory graphical details of the planned Galileo observing sequences can be found at http://tpau.jpl.nasa.gov/point_n.html, or via the IJW Satellites web page. More user-friendly diagrams of the planned Galileo SSI imaging can be found at the SSI Web site, http://www.noao.edu/galileo/ Rosaly Lopes-Gautier of the Galileo NIMS team at JPL adds the following information on possible returns to Io at the end of the Galileo mission, to compensate for the loss of the December flyby data: Will Galileo Return to Io? The option of returning to Io at the end of the nominal Galileo mission was discussed at the Project Science Group meeting held on January 24-25. A study of the options available was done by A.A. Wolf, which assumed the following constraints: (i) return to Io within 2 years of Jupiter Orbit Insertion (JOI), (ii) retain the tail petal apojove at 143 RJ, and (iii) spacecraft must be able to survive radiation damage for 30 to 40 days after Io flyby, in order to be able to transmit the recorded data. Wolf found that the earliest possible flyby date would be 12/11/97. The flyby would be at distances of 75,000 to 100,000 km (compared to JOI's distance of 1,000 km). In this option, the nominal tour could remain unchanged until the 10th orbit, but Galileo's final planned orbit, which includes a targetted Europa encounter, would have to be deleted and two more Callisto flybys would be needed to reduce perijove close enough to Io's orbit to get within tens of thousands of km of Io. The general feeling amongst the investigators was that this non-targetted encounter of Io would not allow us to recover our JOI science objectives, as the flyby distance would be too great. A targetted encounter of Io (meaning a close fly-by distance) could be achieved in this scenario using Callisto flybys, but one more flyby would be needed, so the encounter would occur months after the nominal end of mission. A targetted encounter of Io could be achieved earlier if the tour was modified earlier, in the 8th orbit, changing the aimpoint at G8 in order to target to Ganymede instead of Callisto in the 9th orbit. The overall feeling amongst those present was against doing such drastic modifications to the already planned nominal tour. Other options are available provided we do not need to keep to the 2-year time constraint for the orbital tour. In conclusion, our best hope to have a close encounter with Io is to have an extended mission. It is unclear whether this would be approved by NASA and even under which form it could be proposed. The Galileo project will continue to study options, but it was agreed that the nominal tour (until orbit E11) will remain unchanged. We will next be looking at a possible return to Io after the end of the nominal mission. ___________________________________________________________________________ 9) GALILEAN SATELLITE SPECIAL SESSION AT SPRING AGU Jim Head writes: Torrence Johnson and I are co-sponsoring a special session for the Spring AGU meeting, May 20-24, 1996 in Baltimore, Maryland, entitled Galilean Satellite Geology and Geophysics. Please bring this to the attention of your colleagues. The deadline for abstracts is February 29, 1996 (original and 2 copies to AGU; one copy to be sent to conveners by February 22nd). The full instructions and electronic submittal information are in the December 5 issue of EOS. P03 Galilean Satellite Geology and Geophysics This session focuses on geological and geophysical analyses of the Galilean satellites from Voyager, HST, and Earth-based observations. Specific contributions are solicited which highlight pre-Galileo encounter states of knowledge about processes and histories, and predictions and tests that can be made with Galileo data. Studies of other outer planets' satellites that are relevant to the understanding of the Galilean satellites are also of interest, as are plans for satellite observations during the Galileo mission. Conveners: James Head, Department of Geological Sciences, Brown University, Box 1846, Providence, RI 02912, tel: (401) 863-2526, fax: (401) 863-3978, e-mail: head@pggipl.geo.brown.edu; and Torrence Johnson, Jet Propulsion Laboratory, MS 183-501, 4800 Oak Grove Dr., Pasadena, CA 91109, tel: (818) 393-7957, fax: (818) 393-4530, e-mail: tjohnson@jpltvj.jpl.nasa.gov. ___________________________________________________________________________ 10) LABORATORY PLANETOLOGY SYMPOSIUM AT COSPAR (BELATED ANNOUNCEMENT) During the 31st COSPAR Scientific Assembly, Birmingham, U. K., 14 - 21 July 1996 a symposium on "Laboratory Planetology" is organized. Here is the relevant information on this meeting : B0.5 "Laboratory Planetology" Programme Committee : Main Scientific Organizer : J. Klinger (France) Deputy Organizer : D. Moehlmann (Germany) Organizing Committee : L. Allamandola (USA) J. Blum (Germany) K. Ibadinov (Tajikistan) A. C. Levasseur-Regourd (France) G. Schwehm (The Netherlands) information on the programme This symposium is focussed on laboratory studies relevant to planetology. The main topics are : - Studies of analogues of cometary regoliths and ice - Laboratory simulations and numerical studies of preplanetary growth processes of solid matter - Optical studies of laboratory analogues of planetary, cometary and asteroidal surfaces The contributers are encouraged to present communications on experi- mental and numerical studies related to the preparation of the Rosetta mission. Such studies are for example : Formation processes of dust layers on cometary surfaces, diffusion processes in porous comet nuclei or studies of the propagation of seismic and electromagnetic waves in comet analogues. Laboratory studies related to future Mars missions and to observation campaigns of planetary surfaces are also welcome. Deadline for Abstracts : 15 January 1996 The original of the abstract should be mailed to : Copernicus Gesellschaft 31th COSPAR Scientific Assembly Postfach 49, Max-Planck-Str. 1 D 37189 Katlenburg-Lindau, Germany Tel. +49-5556-1440 Fax +49-5556-4709 Internet :COP@LINAX1.DNET.GWDG.DE Please send a copy of the abstrct to me. Sincerely, J. Klinger Prof. J. Klinger tel. (33) 76 82 42 41 LGGE, B.P. 96 fax (33) 76 82 42 01 F 38402 St. Martin d'Heres CEDEX e-mail : klinger@glaciog.grenet.fr France ___________________________________________________________________________ 11) IJW-RELATED SESSIONS AT THE WESTERN PACIFIC GEOPHYSICS MEETING The Western Pacific Geophysics Meeting to be held in Brisbane, Australia July 23-27, 1996 will include several special sessions of interest to members of the DPS. A full day session is planned to cover the results of the IJW to date. Invited speakers include N. Thomas, J. Spencer, Rene Prange I. de Pater, J. Clarke, G. Ballester, G. R. Gladstone, H. Rucker, M. Klein and K. Imai. A second full day session is planned on the Early Results from the Galileo probe and orbiter. Invited speakers include R. Beebe, H. Niemann, D. Hunten, A. Seiff, B. Ragent, K. Rinnert, R. Carlson, J. Anderson, D. Williams and C. Russell. A third session will cover the remaining outer planets with invited presentations from A. Lane, K. Noll, W. Hubbard, L. Ben Jaffel, Bruce Fegley, A. Sanchez-Lavega, M. Buie, J. Trauger, D. Crisp, L. Trafton and Wing Ip. A session on the SL9 impact with Jupiter being convened by V. Meadows includes invited talks by R. Beebe, S. Brecht, J. Clarke, I. de Pater, D. Hunten, V. Meadows, Osterloo, A. Sprague and Watanabe. Other planetary sessions being organized include: inner planets (convener, J. G. Luhmann); Venus tectonics (convener, R. J. Phillips); and Australian impact craters (convener, L. Hamilton). For more information see URL http://igpp.ucla.edu/spa/activities/meetings/wpgm96.html on the World Wide Web or send an email message to ctrussell@igpp.ucla.edu. Abstract deadline is March 15, 1996 at AGU Headquarters, 2000 Florida Ave. N.W., Washington, DC 20009. ___________________________________________________________________________ 12) POST GALILEO IO WORKSHOP: POSTPONED Originally planned for Lowell Observatory in October 1996, this workshop has been postponed till some later date, due to the loss of the December 1995 Galileo Io remote sensing data. More later... ___________________________________________________________________________ 13) PUBLICATIONS IN THE PIPELINE I have now generated a bibliography of Jovian satellite publications that can be accessed from the IJW Satellites Web site, which will be more convenient and comprehensive than what appears here. For those without Web access, here is the current list of preprints, 1996, and 1995 publications, taken from the bibliography at the Web site. To keep the bibliography manageable, I'm restricting it to papers on the solid parts of the Jovian satellites, and to their gravitationally bound atmospheres. Note in particular the special issue of JGR Planets, October 1995, which had many articles of interest to IJW satellites. All are included in the list below. SUBMITTED: Howell RR. (1996). Thermal emission from lava flows on Io. Icarus Howell RR, Klassen DR. (1996). Volcanic activity on Io during 1987-1992: 4.8 micron photometry. Icarus Goguen, J.D. (1996). Spatially resolved photometry of Callisto using a phase cube of Voyager images. Icarus. McEwen, A.S., N.R. Isbell, K.E. Edwards, and J.C. Pearl (1996). Temperatures on Io: Implications to geophysics, volcanology, and volatile transport. Lunar Planet. Sci. Nash DB, Betts BH. (1996). Ices on Io: Composition and texture. Submitted to Solar System Ices ed. Schmitt B, de Bergh C, Festou M. Kluwer Academic Sartoretti, P., M. Belton, and M. McGrath (1996). SO2 distribution on Io. Icarus. Summers ME, Strobel DF. (1996). Photochemistry and vertical transport in Io's atmosphere and ionosphere. Icarus Trafton LM, Matson DL, Stansberry JA. (1996). Surface/atmosphere interaction and volatile transport (Triton, Pluto, and Io). Submitted to Solar System Ices ed. Schmitt B, de Bergh C, Festou M. Kluwer Academic -------------------------------------------------------------------------- IN PRESS: Calvin, W.M., R.E. Johnson, and J.R. Spencer (1996). O2 on Ganymede: Spectral characteristics and plasma formation mechanisms. Geophys. Res. Lett. Spencer, J.R, and N. M. Schneider (1996). Io on the eve of the Galileo mission. Ann. Rev. Earth. Planet. Sci. -------------------------------------------------------------------------- PUBLISHED IN 1996: Trafton LM, Caldwell JJ, Barnet C, Cunningham CC. (1996). The gaseous sulfur dioxide abundance over Io's leading and trailing hemispheres: HST spectra of Io's C1B2 - X1A1 band of SO2 near 2100 Angstroms. Astrophys. J. 456: 384-392. -------------------------------------------------------------------------- PUBLISHED IN 1995: Blaney, D.L., T.V. Johnson, D.L. Matson, and G.J. Veeder (1995). Volcanic eruptions on Io: heat flow, resurfacing, and lava composition. Icarus 113, 220-225. Buratti, B.J., J.A. Mosher, R.J. Terrile (1995). First observational evidence for condensation of Io's SO2 atmosphere on the nightside. Icarus 118, 418-422. Buratti, B.J. (1995). Photometry and surface structure of the icy Galilean satellites. JGR Planets 100: 19061-19066. Burnett, DS, (1995). Competition between Na2SO4 and Na sulfide in the upper crust of Io J. Geophys. Res. - Planets 100: 21265-21270 Calvin W.M., R.N. Clark, R.H. Brown, and J.R. Spencer (1995). Spectra of the icy Galilean satellites from 0.2 to 5 microns: A compilation, new observations, and a recent summary. JGR Planets 100: 19041-19048. Carr MH, MJS Belton, K Bender, H Breneman, R Greeley, JW Head, KP Klaasen, AS Mcewen, JM Moore, S Murchie, RT Pappalardo, J Plutchak, R Sullivan, G Thornhill, J Veverka (1995). The Galileo imaging team plan for observing the satellites of Jupiter Journal of Geophysical Research - Planets 100 18935-18955 Domingue DL, G. W. Lockwood, D. T. Thompson (1995). Surface textural properties of icy satellites: A comparison between Europa and Rhea. Icarus 115, 228-249. Goldstein, SJ, and KC Jacobs (1995). A recalculation of the secular acceleration of Io. Astronomical Journal 110: 3054-3057. Hall, D.T., D.F. Strobel, P.D. Feldman, M.A. McGrath, and H.A. Weaver (1995). Detection of an oxygen atmosphere on Jupiter's moon Europa. Nature 373, 677-679. Johnson TV, Matson DL, Blaney DL, Veeder GJ, Davies AG. (1995). Stealth plumes on Io. Geophys. Res. Lett. 22: 23. Khanna RK, Pearl JC, Dahmani R. (1995). Infrared spectra of solid phases of sulfur trioxide : Possible identification of solid SO$_3$ on Io's surface. Icarus 115: 250-57 Matson DL, TV Johnson, DL Blaney, GJ Veeder, (1995). Ground-based observations of Io. Reviews of Geophysics 33 Suppl. 505-508 McEwen AS. (1995). SO$_2$ rich equatorial basins and epeirogeny of Io. Icarus, 113: 415-422. Nakamura T, M Yoshikawa, (1995). Close encounters and collisions of short-period comets with Jupiter and its satellites. Icarus 116, 113-130 Nash DB, Betts BH. (1995). Laboratory infrared spectra (2.3-23 microns) of SO_2 phases: Applications to Io surface analysis. Icarus 117: 402-419 Noll, K.S., H.A. Weaver, and A.M. Gonnella (1995). The albedo spectrum of Europa from 2200 A to 3300 A. JGR Planets 100: 19057-19059. Pappalardo R.T. and R. Greeley (1995). A review of the origins of subparallel ridges and troughs: Generalized morphological predictions from terrestrial models. JGR Planets 100: 18985-19007. Sartoretti P., M.McGrath, A.McEwen, J.Spencer. (1995). Post Voyager Brightness Variations on Io. Journal of Geophys. Res. Planets. 100: 7523-7530. Schenk, P. (1995). The mountains of Io. Astronomy 23, 1: 46-51 Schenk, P. (1995). 3-D Moons: Hyperstereo of the outer solar system, Stereo World, 22, 1, 14-19. (Copies can be obtained by writing Stereo World PO Box 398, Sycamore, OH 44882). Schenk, P. (1995). The geology of Callisto. JGR Planets 100: 19023-19040. Schenk PM, JM Moore (1995). Volcanic constructs on ganymede and enceladus: Topographic evidence from stereo images and photoclinometry Journal of Geophysical Research - Planets 100: 19009-19022 Smythe WD, R. Lopes-Gautier, A. Ocampo, J. Hui, M. Segura, L.A. Soderblom, D.L. Matson, H.H. Kieffer, T.B. McCord, F.P. Fanale, W.M. Calvin, J. Sunshine, E. Barbinis, R.W. Carlson, P.R. Weissman (1995). Galilean satellite observation plans for the near-infrared mapping spectrometer experiment on the Galileo spacecraft. J.Geophys. Res., 100: 18,957-18,972. Spencer JR, WM Calvin, MJ Person (1995). Charge-coupled device spectra of the Galilean satellites: Molecular oxygen on Ganymede. Journal of Geophysical Research - Planets 100: 19049-19056 Spencer JR, Spencer JEB, Griep D. (1995). Jupiter I (Io) Intl. Astron. Union Circular 6149 Tamppari LK, JR Spencer, TZ Martin (1995). Observing the icy Jovian satellites with the Galileo photopolarimeter radiometer instrument. Journal of Geophysical Research - Planets 100: 18973-18983 Wienbruch U, Spohn T. (1995). A self sustained magnetic field on Io? Planet. Space Sci. 43: 1045 Wong MC, Johnson RE. (1995). The effect of plasma heating on sublimation- driven flow in Io's atmosphere. Icarus 115: 109-118 _____________________________________________________________________________