Cassini Weekly Significant Events for 05/18/00 – 05/24/00

The most recent spacecraft telemetry data was acquired from the Goldstone tracking station on Wednesday, 5/24. The
Cassini spacecraft is in an excellent state of health and is operating normally. Activities this week include the first
time use in the background sequence of the new 82.95k and 22.12k telemetry modes. The Backup ALF Injection
Loader (BAIL) and Engine Gimbal Actuator (EGA) portions of Periodic Engineering Maintenance were executed. The
Reaction Wheel Assembly (RWA) portion was replaced by an RWA friction test, followed by transition to RWA
control. Real time commands were sent to update flight software for the Cosmic Dust Analyzer (CDA), Composite
Infrared Spectrometer (CIRS), Radio and Plasma Wave Science (RPWS), and Ultraviolet Imaging Spectrograph
(UVIS) instruments. The speed of the spacecraft can be viewed on the “Where is Cassini Now?” web page (
“http://www.jpl.nasa.gov/cassini/today/” )

A joint Cassini-RPWS/Galileo Conjunction Experiment was performed. This conjunction, like the one in February,
provided the opportunity to observe Jovian radio emissions in a stereoscopic sense. Both the Cassini and Galileo
spacecraft were very nearly aligned relative to Jupiter. Using the small, but finite differences in viewing angle
offers the possibility of understanding some of the beaming characteristics of Jovian radio emissions. One of our
team members led an effort to do a similar experiment during Instrument Checkout 1 (ICO1) and the Earth flyby
using Cassini and Wind (a spacecraft in Earth orbit). Those results have now been accepted by the Journal of
Geophysical Research (apparently the first Cassini science paper to be published). They report that Jovian
decametric arcs have a beam width of 1.5 +/- 0.5 degrees and that those radio emissions associated with the moon Io
sweep around Jupiter with the rotation rate of Io and not that of Jupiter. The Cassini observations during this
interval look very good and Jupiter was quite active in the radio frequencies monitored. Galileo data was properly
recorded and will be available for analysis in a month or so.

A strategy meeting for Trajectory Correction Maneuver 14 (TCM 14) was held and established the schedule and
overall design strategy for this maneuver. TCM 14 will be a main engine maneuver of about 0.5 meter per second and
will execute on June 14.

A telecon was held to discuss possible science observations during the Saturn Orbit Insertion time period. This
interval will provide the highest resolution remote sensing data of the rings for the entire mission and will provide
unique data on Saturn’s magnetosphere as well.

The plan to provide Science-data-over-the-Internet to remote sites during ICO2 is ready. RPWS and Magnetospheric
Imaging Instrument (MIMI) teams are set to use this mode. Other instrument teams are verifying their ability to
accept data in this mode and should be ready by the end of this week.

System Engineering and Mission Support & Services Office team members met to discuss the criteria for final
transition from the Central Database (CDB) to Distributed Object Manager (DOM) as the Cassini file repository. DOM
has been in operational use since January and the flight team is currently comfortable with its use.