Cassini Significant Event Report
For Week Ending 01/16/98
MSO Significant Events input for week of Friday 01/09 through Thursday 01/15:
Most recent Spacecraft status is from the DSN tracking pass on Wednesday
evening, 1/14, over Canberra.
The Cassini spacecraft is in an excellent state of health and is operating
nominally. The C5 sequence continues to execute onboard the spacecraft. C5
activities will be complete on Saturday, 1/17. The C6 sequence will begin
executing on Sunday afternoon, 01/18/98. The speed of the spacecraft can be viewed on the "Where is Cassini Now?" web page (http://saturn.jpl.nasa.gov/operations/present-position.cfm)
Inertial attitude control is being maintained using the spacecraft's hydrazine
thrusters (RCS system). The spacecraft continues flying in a High Gain Antenna-
to-Sun attitude. It will maintain the HGA-to-Sun attitude, except for needed
trajectory correction maneuvers, for the first 14 months of flight.
Communication with Earth during early cruise is via one of the spacecraft's two
low-gain antennas; the antenna selected depends on the relative geometry of the
Sun, Earth and the spacecraft. The downlink telemetry rate is presently 948 bps.
Spacecraft Activity Summary:
On Friday, 01/09, there were no changes in spacecraft configuration.
On Saturday, 01/10, the Solid State Recorder (SSR) record and playback pointers
were reset, according to plan. This housekeeping activity, done approximately
weekly, maximizes the amount of time that recorded engineering data is available
for playback to the ground should an anomaly occur on the spacecraft.
From Sunday, 01/11, through Tuesday 01/13, there were no changes in spacecraft
On Wednesday, 01/14, the AACS Reaction Wheel Assembly (RWA) Exercise and the
Engine Gimbal Actuator (EGA) Exercise were performed. These activities are
performed approximately every three months, for the purpose of assuring
lubricants remain evenly distributed in the RWA and EGA mechanisms.
Upcoming spacecraft events:
Events for the week of 01/16 through 01/22 include: a reset of the SSR pointers
(01/16), dropping the downlink telemetry rate from 948 bps to 40 bps (01/17),
execution of the AACS BAIL Maintenance activity (01/17), a Periodic Instrument
Maintenance activity (01/21), a SSR Flight Software Partition Maintenance (01/
21), and another reset of the SSR pointers (01/22).
Over the past week Cassini had 1 DSN track period (01/14). In the coming week,
there will be 4 DSN passes - one on Saturday, 01/17, two on Wednesday, 01/21
(One each over Goldstone and Canberra.), and one on Thursday, 01/22.
Additional information about Cassini-Huygens is online at http://saturn.jpl.nasa.gov.
Cassini will begin orbiting Saturn on July 1, 2004, and release its piggybacked Huygens probe about six months later for descent through the thick atmosphere of the moon Titan. Cassini-Huygens is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Office of Space Science, Washington, D.C.