Summary of Magnetospheric Physics Working Group
Group Leader: Melissa McGrath, Space Telescope Science Institute
 
The Magnetospheric Effects Working Group considered the topics of
Jovian aurorae, the Io torus, Jovian radio emissions, dust and the Na
magnetonebula.  The key driver in terms of magnetospheric effects will
be the amount of dust and gas produced by the comet fragments
throughout the Jovian magnetosphere.  Current estimates of both the gas
and dust production rates are very low.  Nevertheless, we do know that
there is more dust in the magnetosphere than usual. Furthermore, much
of the dust will not intersect the planet during the comet fragment
impacts, and will remain in orbit in the magnetosphere for an extended
period of time, allowing for the possibility of cumulative effects.

Extensive observations are planned of all the phenomena mentioned
above  (i.e., the Jovian aurorae, the Io torus, the Jovian radio
emissions and the Na magnetonebula).  In addition, reasonably good sets
of baseline observations also exist in these areas. The one notable
exception is and will be observations of the dust itself.  Since there
have been predictions of changes in the morphology of the dust as it
interacts with the magnetopause (possibly charging, followed by dust
particle breakup, POSSIBLY implying brightening of the dust due to
larger surface area after breakup), we encourage amateur observations
to monitor the dust morphology (i.e., wide-field imaging) beginning as
soon as possible, but especially covering the time period when the
fragments are in the 50-150RJ vicinity.  Most observing time will be
concentrated during a 2-3 week period centered on the impacts, so
regular monitoring of the fragments and dust will be limited well
before impact.

Notable predictions from the magnetospheric effects included: formation
of a new dust ring at 5RJ (Horanyi) - [long time scale, not easily
observable]; radio emissions from atmospheric discharges associated
with the fragment impacts, i.e., lightening (Kaiser); decrease in the
synchrotron emission (dePater); increased mass loading of the magneto-
sphere, including the Io torus, implying increased co-rotation lag and
increased field- aligned currents; and general idea that Galileo will
see a much different dust environment than was seen during the Ulysses
encounter (1991).



I. What is Really Known?
	A. Ephemeris of the fragments, i.e., where they will be when; times for
           crossing satellite plane known, and times for crossing magnetopause 
           can be estimated (the uncertainty is the poorly-known location of
           magnetopause).

	B. Dust will be the important driver for magnetospheric phenomena.
	   1. Dust production estimates are low, but there is more dust
	      in the magnetosphere now than usual, and this will continue to be
              the case for some time to come.
	   2. A significant amount of dust will not intersect the
	      planet and will remain in the magnetosphere.

	C. Gas Production is low.

	D. Good baseline observations of Io, the Io torus, the aurorae,
           radio emissions, and the Na magnetonebula exist.

	E. Predictions
		1. Lighting-Up of the magnetopause by dust charging,
                   breaking up as it crosses the magnetopause. (Dessler)
		2. Formation of a new dust ring @ ~5 Rj on a long time scale 
                   (Horanyi)
		3. Radio emissions from atmospheric discharge-Lightening
		  (Kaiser) 
		4. Decrease in synchrotron emission (dePater)
		5. Increased co-rotation lag and field-aligned currents due to
                   mass loading
		6. Galileo will see a much different dust environment than
		   e.g. Ulysses did in 1991

II. What are the key and diagnostic observations to be made?
        A. Observations of the Io torus with ground-based, IUE, HST, and EUVE 
	   will be made.
        B. Extensive radio observations will be made.
        C. Observations of the Jovian aurora will be made in the IR and UV.
        D. Observations of the Na magnetonebula will be made.
        E. Coordinated, pre-impact observations are recommended around 
	   opposition.
    
III. What areas are not being addressed?
	A. Wide-field observations of dust, dust crossing the magnetopause to 
           look for morphological changes in it.  Recommend amateur observations
           in this area.

IV. Miscellaneous
	A. Solar data will be provided on c1993e bulletin board (Susan
           McKenna-Lawlor)
	B. Ulysses solar wind data will be provided (Mike Kaiser)
	C. All observers should check summer 1992 data for evidence of
           pre-breakup activity.
	D. Post impact observations should be made in 1995 .
	E. What is the interplanetary dust flux onto Jupiter/magnetosphere?
	F. When does the leading dust spike reach ~100Rj?