Status Report

Cassini Weekly Significant Events for 01/04/00 – 01/10/01

By SpaceRef Editor
January 16, 2001
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The most recent spacecraft telemetry was acquired from the Madrid tracking station on Wednesday, January 10.  The Cassini spacecraft is in an excellent state of health and is operating normally.    The speed of the spacecraft can be viewed on the "Present Position" web page ( "" )
Phase E of the Jupiter subphase continued this week.  Activities included Cassini Plasma Spectrometer (CAPS) solar wind observations, atmospheric cyclic observations, Io eclipse observation, a ring observation at 90 degree phase angle, Europa, Callisto, and Ganymede observations, a Ganymede and Europa eclipse observation, Ultraviolet Imaging Spectrometer (UVIS) stellar occultation, Composite Infrared Spectrometer (CIRS) feature track observation, and a UVIS / Hubble Space Telescope aurora observation.
Other activities included uplink of the CAPS, Imaging Science Subsystem (ISS) and Visual and Infrared Mapping Spectrometer (VIMS) Instrument Expanded Block (IEB) loads, CAPS IEB load for gain tests and execution of the tests, command to clear the Solid State Power Switch (SSPS) for the AACS Valve Drive Electronics Control Unit-B, AACS Reaction Wheel Assembly (RWA) memory readout (MRO), AACS highwater mark clears, uplink of AACS RWA unload bias overlay programs, Magnetospheric Imaging Instrument (MIMI) Ion and Neutral Camera (INCA) collimator high voltage commanded to off, a reaction wheel momentum unload, CDS-A and CDS-B automatic SSR repairs, CIRS focal plane assembly control set point to 21, MIMI to science mode mini-sequence, reset CDS SSPS trip counters, AACS reset of total RPM counter, and a MIMI processor MRO and turn on of the replacement heater for the Low Energy Magnetospheric Measurement Subsystem (MIMI LEMMS).
Magnetometer Subsystem (MAG) personnel have been looking at the recent MAG data in the vicinity of the Jovian bow shock crossings identified recently by the other Cassini investigations and reported a number of interesting observations. First, the outbound shock crossing at 365/2212 is very clear in the field data and is accompanied by a large overshoot indicative of a supercritical shock. Hydromagnetic waves are also evident upstream of the shock. Mirror mode waves are present in the magnetosheath for much of the day. Second, the inbound and outbound shock crossings at 366/0959 and 1219 are also prominent and contain overshoots. There appear to be several close approaches to the bow shock near 1103, 1115 and 1212 while Cassini is in the magnetosheath suggesting that the spacecraft is skimming along the moving shock front.
Radio and Plasma Wave Science (RPWS) personnel reported that Cassini entered the Jovian magnetosphere around mid day on January 9.  RPWS observed trapped continuum radiation extending down to about 500 Hz, corresponding to a plasma density of about 3 x 10^-3 at about 1315.  The actual magnetopause crossing time is still in question, however. Based on previous experience with Galileo in this region of the magnetosphere, it seems that on occasion, the density gradient can be very gradual and the location of the boundary not very clear in the wave data.  Cassini exited the magnetosphere that same day reentering the magnetosheath and then went back in to the magnetosphere at about 0700 on day 10.  For the period on day 9 when Cassini was inside the magnetosphere, Galileo also was still inside, hence the two spacecraft were inside Jupiter’s magnetosphere at the same time.
Instrument Operations and the Multi Mission Image Processing Laboratory (MIPL) have produced and delivered 16238 ISS images -10522 Narrow Angle Camera and 5716 Wide Angle Camera – and 2108 VIMS cubes since Jupiter encounter began.
The Radio Science Ka-band exciter and traveling wave tube amplifier were turned on again, after RADAR observations concluded, to support DSS-25 upgrade implementation testing.
The final approval meeting for C24 was held this week.  The sequence is approved for uplink and will begin execution next week.  The Sub Sequence Generation Sequence Change Request meeting was held for C25.
Revision A of the Science Operations and Planning Computer User’s Handbook, and the SPICE Events Kernel Development Plan were completed and distributed this week.
A draft agenda has been released for the Planetary Science Group meeting to be held in January at JPL.
Installation of Telemetry, Command & Data Management (TC&DM) 25.2.2 occurred this week. MSS D7.3.1 was deployed on all SOPCs ahead of target date.  Deployment included 150 prerequisite patches and two software packages.
Outreach personnel staffed a poster presentation on Cassini classroom activities at the joint meeting of the American Association of Physics Teachers and the American Astronomical Society this week.
Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Cassini mission for NASA’s Office of Space Science, Washington, D.C.
Cassini Outreach
Cassini Mission to Saturn and Titan
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration

SpaceRef staff editor.