__________________________________________________________________________ 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 E-mail issue 4 October 8th, 1993 Editor: Discipline Leader: John Spencer Jay Goguen Lowell Observatory Jet Propulsion Lab, M.S. 183-501 1400 W. Mars Hill Rd. 4800 Oak Grove Dr. Flagstaff, AZ 86001 Pasadena, CA 91109 Voice: (602) 774-3358 Voice: (818) 354-8748 Fax: (602) 774-6296 Fax: (818) 354-0966 Internet: spencer@lowell.edu Internet: jdg@scn2.jpl.nasa.gov ------------------------------------------------------------------------------ EDITORIAL COMMENTS Most of this newsletter consists of information from Jay about IJW in general, plans for our get-together at the DPS meeting, and plans for election of a new discipline leader. I've also added a few notes about Io volcanic activity and some new publications at the end. ------------------------------------------------------------------------------ IJW SATELLITES LUNCH AT THE DPS, THURSDAY 12:00-1:30 PM, Executive Board Room There will be a MEETING of the IJW SATELLITES Discipline at the DPS meeting on Thursday 21 October 1993 from 12:00 - 1:30 PM in the EXECUTIVE BOARD ROOM, located on the other side of the lobby from the meeting rooms. This room contains a conference table with 14 chairs, so come early to get a good seat. Food may be obtained from the hotel lunch line and consumed during the informal session. Please bring recent results and ideas for discussion. The purpose of the session is to promote communication between people doing satellite-related research and other interested parties. Everyone is welcome and encouraged to attend. One item of business that will be on the agenda is: NOMINATION OF THE NEW SATELLITES DISCIPLINE LEADER I have been honored to serve as the Satellites Discipline Leader for the past 4 years. During this time, the Satellites Discipline has been an active participant in special joint sessions at AGU meetings, held annual sessions at the DPS, contributed significantly to July 1992 Annapolis TVPJS meeting, played a major role at the SJI Io Conference this past June, and strengthened communication between our members and the other disciplines, especially the Torus discipline. At the DPS, I will step aside as the Satellites Discipline Leader, give someone else a chance to serve, and devote the additional time to doing science. The suggested nominal term for Discipline Leaders is 3 years, however there has been no history of elections or other mechanism for change or renewal. There is a suggestion that an outgoing leader nominate a replacement for approval by the Steering Committee, however I think it is important that the Discipline membership have a say in this important choice. ACTION ITEM: Please NOMINATE your candidate for Satellite Discipline Leader. You can submit nominations via e-mail, phone, or any other medium of your choice to Jay Goguen (jdg@scn5.jpl.nasa.gov, (818) 354-8748 phone) or John Spencer (spencer@lowell.edu, (602) 774-3358 x17, phone). Voice nominations subject to a second from those in attendence will also be requested at the session. Any candidate must agree to serve before she/he can be approved by the Steering Committee. Voting for nominees will be by a show of hands during the session. The approved nominee will assume the office immediately, subject to final approval by the Steering Committee which will meet on Thursday evening. Jay Goguen ------------------------------------------------------------------------------ SATURN'S RINGS PLANE-CROSSING WORKSHOP AT THE DPS, TUESDAY 2:00-4:00 PM, HOSPITALITY SUITE 431 Of interest to Satellites Discipline members is the Saturn's Ring Plane Crossing Workshop organized by Phil Nicholson (nicholson@astrosun.tn.cornell.edu, (607) 255-8543 phone) to be held Tuesday afternoon. In addition to rare opportunities to observe unique ring-related phenomena, there will be satellite mutual events and eclipses, as well as opportunities to observe faint satellites in the rings region. Phil Nicholson and Mark Showalter have been promoting this opportunity and they have an e-mail distribution list that you may like to get on. Relevant notes from that list will be passed along through this newsletter. Jay Goguen ------------------------------------------------------------------------------ This overview of the IJW, its history and charter was recently received from the Steering Committee Chair, D. M. Hunten, for distribution. Please look it over to remind yourself of where we are now, how we got there, and where we should be going. Please submit any comments to the author or your Discipline leader. THE INTERNATIONAL JUPITER WATCH D.M. Hunten, July 13, 1993 EXCERPT FROM THE PREFACE TO SP-494 (1989) "Time-variable phenomena in the Jovian system" "When [the exciting prospects of the Galileo mission] are incorporated with the rich history and future capabilities of Jupiter studies utilizing astronomical techniques from the ground and from earth-orbit, it is not surprising to find growing research interest in a concerted international effort to coordinate an observational program that will provide a solid factual basis for the future study of time-variable phenomena in the Jupiter system. Called the International Jupiter Watch (IJW), this "grass-roots" organization seeks to build on the rich legacy of Voyager and Pioneer, and the more than two decades of ground-based and Earth-orbital planetary astronomy, to ensure that, by the time Galileo is injected into orbit, planetary science will be in the best possible position to advance our knowledge of the jovian system." Many of the IJW organizers were Galileo people, and a close connection has always been maintained. IJW has the formal support of the Galileo PSG, and the Project offers a small amount of other support. The following brief history is adapted from the IJW's first publication, a document of limited circulation developed at the May 1986 meeting: "The idea of a Jupiter Watch program grew out of a series of discussions among Chris Russell, Imke de Pater, and Torrence Johnson and several colleagues in the early 1980's. These informal discussion suggested that there was a need for such a program and much latent support for one. At that time the Galileo launch seemed to be imminent, and any Jupiter Watch program would derive benefit if it were to include the interval of Galileo observations. Russell obtained a small grant from the California Space Institute to hold a workshop which would prepare a report on the feasibility of a Jupiter Watch program. A discussion session was held at the October 1985 DPS meeting to poll a larger segment of the community and get further ideas as to how to proceed. As a result of these discussions and a larger set of questionnaires, it was decided to hold the workshop at the Kennedy Space Center just prior to the lauch of Galileo in May 1986. The Challenger disaster cancelled the scheduled launch, but the community was strongly in favor of continuing with the planned workshop at a more accessible location. We changed the date to make it more convenient for Galileo investigators and changed the venue to the Pasadena Convention Center. Over sixty scientists attended the workshop, only three of whom obtained partial support for their travel from the workshop. Four of the attendees were from abroad." The workshop and organizing meeting were held in Pasadena on May 13 and 14, 1986. The report was prepared by the members of the first Steering Committee, consisting of Russell (chair), de Pater, and Johnson along with Mike Belton, Don Hunten, and Bob West, who also acted as editor. Russell was later succeeded as chair by Dave Morrison and currently Hunten, both also Galileo IDS's. There are six Working Groups, whose Chairs take care of nearly all the actual business of the IJW: coordination of various observers and rapid reporting by E-mail of preliminary results. Jay Goguen (Satellites) Ted Kostiuk (Aurora) Glenn Orton (Atmosphere) Imke de Pater (Radio and Magnetosphere) Nick Schneider (Torus) Kent Wells (Laboratory and theory) They are all members of the Steering Committee, along with half a dozen others chosen with emphasis on international representation. The normal term is three years. Working Groups usually meet during the DPS, and in addition two general conferences have been held. The first, in Flagstaff in 1987, produced the SP- 494 "Time-variable phenomena in the Jovian system". The second was held in Annapolis in 1992; publication is forthcoming in JGR-Planets. The members-at-large of the Steering Committee are currently Mike Belton Mike Klein Ted Kostiuk Dave Morrison Chris Russell John Spencer Bob West Tadashi Asada (Japan) Catherine de Bergh (France) Steven Miller (UK) Fernando Moreno (Spain) Boris P. Ryabov (Ukraine) Nicholas Thomas (Germany) During the Annapolis meeting it became clear that many people were as interested in Saturn as Jupiter, and the Steering Committee agreed that it would be valuable to establish a more formal connection with Cassini, similar to the existing one with Galileo. The suggested support is almost entirely moral; in addition, IJW wants Cassini scientists to be aware of what it may be able to contribute scientifically, and to stimulate possible joint endeavors. Hunter Waite, who was at the meeting, was asked to make the initial approach, and there have also been informal discussions with Dennis Matson. If the connection is established, IJW will have to consider a change of name; IJSW springs to mind. -------------------------------------------------------------------------------- VOLCANIC ACTIVITY UPDATE John Spencer and Mark Shure observed Jupiter eclipses of Io using the new IRTF facility camera "NSFcam", a 256^2 1-5 micron InSb camera, on September 3 and 5 UT. Io was 30 degrees from the sun and observations we made in daylight, but were nonetheless fairly successful, showing that Io's volcanic activity will be observable from the ground as late as one month before the Galileo Io encounter, when solar elongation will be similar. The data are not yet fully reduced, but it appeared that volcanic activity was at about the same low level that we've seen since June 1991. Incidentally, we also caught a few c. 0.5-arcsec resolution 5-micron full-disk images of Jupiter, some in daylight with the sun falling on the IRTF secondary ring, and some after sunset at 3.5 airmasses. So this also bodes well for Jupiter monitoring prior to the Galileo encounter. ------------------------------------------------------------------------------ NEW ABSORPTION FEATURE ON GANYMEDE (CONTINUED) The 2/% deep, 100 A wide, 5770 A wavelength absorption band discovered on Ganymede by Spencer and Calvin in March 1993 (mentioned in the last newsletter) has now also shown up in CCD spectra of Ganymede taken in 1992 by Will Grundy and Uwe Fink at the University of Arizona. We still have no idea what causes it, though... ----------------------------------------------------------------------------- GALILEO UPDATE Planning of close-up observations of Europa (closest approach c. 30,000 km) and Io (closest approach c. 1000 km) prior to Jupiter orbit insertion are now well advanced, and should be completed this fall. Only about one hundred 400 x 400 pixel images of Io will be possible due to tape recorder limitations, with best resolution of about 30 meters pixel-1 for a few small areas. Full disk mosaics of Io by NIMS (c. 60 km resolution) and PPR (c. 200 km resolution) will probably also be possible. Some images of Europa will probably also be taken, with a resolution of c. 500 meters pixel-1, a fourfold improvement over best Voyager Europa resolution. ------------------------------------------------------------------------------ PUBLICATIONS IN (OR EMERGED FROM) THE PIPELINE G.J. Veeder, D.L. Matson, T.V. Johnson, D.L. Blaney, and J.D. Goguen. Io's Heat Flow from Infrared Radiometry: 1983-1993. Submitted to JGR Planets, June 1993. (not submitted to Icarus as stated in the last newsletter) D.P. Hamilton and J. A. Burns (1993). Ejection of dust from Jupiter's Gossamer Ring. Nature 364, 695-699. S.L. Manatt and A.L. Lane (1993). A Compilation of the Absorption Cross-Sections of SO2 from 106 to 403 nm. J. Quant. Spectroscopy & Radiative Transfer, 50, 267-276. N.J. Sack, R.A. Baragiola, and R.E. Johnson (1993). Effect of Plasma Ion Bombardment on the Reflectance of Io's Trailing and Leading Hemispheres. Icarus 104, 152-154. R.E. Johnson and M.A. McGrath (1993). Stability of the Io Plasma Torus / Atmosphere Interaction. Geophys. Res. Lett. 20, 1735-1738. A. Mallama, D.S. Caprette, P. Nelson, J. Park, D.F. Collins, and M. Vojtisek-Lom. Precise timings of Galilean satellite eclipses and assesment of the E-3 ephemeris. Submitted to Icarus, September 1993. K.S. Noll, H.B. Hammel, L. Young, J. Joiner, J. Hackwell, D.K. Lynch, and R. Russell (1993). 3 to 13 micron spectra of Io. Icarus 104, 327-330. -------------------------------------------------------------------------------