News | March 5, 1998
Significant Event Report for Week Ending 3/6/1998
Cassini Significant Event Report
For Week Ending 03/06/98
The Cassini spacecraft is presently traveling at a speed relative to the sun of approximately 138,000
kilometers/hour (~86,000 mph) and has traveled approximately 369 million kilometers (~229 million miles)
since launch on October 15, 1997.
The most recent Spacecraft status is from the DSN tracking pass on Thursday, 03/05, over Canberra. The
Cassini spacecraft is in an excellent state of health and is operating nominally, with the C6 sequence executing
onboard. 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 to fly in a High Gain Antenna-to-Sun attitude. It will maintain the HGA-to-Sun attitude,
except for planned 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 40 bps.
Spacecraft Activity Summary:
From Friday, 02/27, through Monday, 03/02, there were no changes in spacecraft configuration.
On Tuesday, 03/03, 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.
On Wednesday, 03/04, a maintenance activity was performed on the SSR Flight Software Partitions. This
activity repairs any SSR double bit errors (DBEs) which have occurred in the code-containing portions of the
Flight Software partitions during the preceding period. Telemetry following Wednesday's activity indicated
that the three pending DBEs were all in the unused portion of the flight software partitions. The clearing of
these (by the partition copy procedure) will be scheduled for an upcoming DSN pass.
On Thursday, 03/05, there were no changes in spacecraft configuration.
Events for the week of 03/06 through 03/12 include: clearing of the SSR DBEs mentioned above (to be
scheduled), a reset of the SSR pointers (03/10), approval of the C7 sequence (03/11), update of spacecraft
mass properties (03/ 12; based on the successful TCM on 2/25), FP log maintenance (03/12), and uplink of
C7 Sequence (03/12). The C7 sequence will begin on Sunday, 3/15/98.
Over the past week Cassini had 8 DSN tracks occurring daily from Friday (02/27) through Thursday
(03/02). In the coming week there will be 8 DSN passes.
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.
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