Cassini Significant Event Report

For Week Ending 08/10/01

The most recent spacecraft telemetry was acquired from the Madrid tracking
station on Wednesday, August 8. The Cassini spacecraft is in an excellent
state of health and is operating normally. Information on the
spacecraft's position and speed can be viewed on the
"Present Position"
web page.


Recent spacecraft activities include the conclusion of a Magnetospheric
and Plasma Science observation, a Radio and Plasma Wave Science (RPWS)
High Frequency Receiver Calibration, powering off the Composite Infrared
Spectrometer, and an autonomous memory load partition repair of Solid
State Recorder-B.


The third and final of the instrument muting tests was completed this
week. This test puts Cassini in a position to perform future Probe
Checkouts with the instruments placed in a sleep state and having their
Bus Interface Unit's transmission port 'muted'. Prior to these tests,
Probe Checkouts required the Cassini instruments to be powered off for the
duration of the activity. This new capability will allow the instruments
to avoid incurring an undesired cycle as they are powered off and on again.


In support of the C28 sequence process, the "b" version of the C28
sequence products was released, as was the draft package for the
Preliminary Sequence Integration and Validation meeting. A meeting was
held to define the Integration Test Laboratory (ITL) simulation support
for Flight Software Normalization activities for the Cosmic Dust Analyzer
(CDA) and Visual and Infrared Mapping Spectrometer. Also discussed were
the results of the successful instrument mute tests and the corresponding
impact on C28 testing.


A preliminary package of the Command and Data System Version 9 Flight
Software was delivered to the ITL for Huygens Probe relay testing. Probe
relay testing has begun in subsystem mode with this new build of the
flight software.


The entire set of modules for Mission Sequence Subsystem (MSS) D7.6 has
been successfully tested both individually and in small groups by the ITL
and High Speed Simulator, and an integrated retest is planned for later
this week in preparation for the MSS D7.6 delivery.


The CDA Remote Terminal Interface Unit (RTIU) has been successfully
tested, and the new RTIU for RPWS is scheduled to begin testing later this
week. The RTIU converts the 1553 real-time instrument data interface to an
Ethernet interface for data processing and performance testing with the
instrument engineering model.


An on-line Risk Management Tool has been completed for Cassini. Mission
Assurance has begun the process of entering data from the Significant Risk
List, for risk tracking and assessment. Following a few additional
modifications and data entry, the tool will be rolled out for use by the
Cassini Risk Team.


A delivery review for the Advanced Multi-Mission Operations System V26.2
release was held this week. This version implements necessary capabilities
for the Gravitational Wave Experiment.


The Program Review Plan has been updated and distributed to the flight
team for review by Mission Assurance. The plan reflects the high-level
review process to assess readiness for SOI, probe relay, and Saturn tour
operations, and includes an integrated schedule of program level reviews.


The Cassini Design Team met to collect comments from Cassini personnel on
the review process for the Ground Data System and Tour Downlink Operations
Concepts reviews. These "lessons learned" comments are being collected by
System Engineering for evaluation and implementation in future reviews.


The Mission Planning team held a review of the Cassini navigation tracking
requirements. Topics included having ranging "on" at all times as a
default, reductions in the 2-way Doppler requirement, and alternative
solutions to a requirement that one third of all Cassini DSN support come
from the Madrid tracking station.


A Cassini image of Jupiter is featured in the September issue of Sky and
Telescope Magazine.



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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