Status Report

Cassini Significant Events for 07/11/02 – 07/17/02

By SpaceRef Editor
July 21, 2002
Filed under , ,

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Tuesday, July 17. The Cassini spacecraft is in an
excellent state of health and is operating normally. Information on the
present position and speed of the Cassini spacecraft may be found on the
"Present Position" web page located at .

Instrument activities this week included Composite InfraRed Spectrometer
Instrument and Cassini Plasma Spectrometer (CAPS) calibrations,
development of Radio and Plasma Wave Science (RPWS) Instrument Tour
Observation Modes, and calibration of the RPWS High Frequency Receiver.
The Visual and Infrared Mapping Spectrometer performed a star
characterization, scattered light observation, instrument solar port
observation, and executed an instrument spectral calibration. The
Ultraviolet Imaging Spectrograph (UVIS) performed instrument solar port
and SPICA observations.

In addition, spacecraft activities included a Reaction Wheel momentum
unload, clearing of the AACS high water marks, and uplink and execution
of an ACS Gyro Calibration mini-sequence.

The purpose of the mini-sequence was to determine the misalignments,
scale factors, and scale factor uncertainties for the Inertial Reference
Unit (IRU). The misalignments and scale factors map directly into
accurate attitude estimation. The uncertainties, which are currently
quite large, directly affect how long we can suspend stellar ID before
we accumulate large attitude errors. The activity consisted of a series
of turns using the reaction wheels. By using the scalable feature of
the parameter estimation portion of the Cassini Attitude Control Flight
Software, the spacecraft was able to autonomously compute the necessary
information. All computed values were significantly below tolerances
and indicate excellent performance of the IRUs. This was a first time
activity for the Cassini spacecraft and in fact, a first time activity
for any JPL mission.

The Integrated Test Laboratory completed exercising a procedure to
normalize RPWS and UVIS flight software. This activity will be
performed on-board the spacecraft in late July.

The Cassini/Huygens program held a joint independent review of the
Huygens Probe Mission. Participants from JPL, the European Space Agency,
and private industry supported the two-day review. Included on the
agenda were mission design, navigation strategy, critical sequence
design, and ground and flight operations scenarios. Instrument
Operations has collected all presentations from the on-going Science and
Uplink Office Seminar series and additional pertinent Cassini training
materials for reproduction on a MAC/PC compatible CD-ROM. The CD makes
these materials readily available for on-going training.

The second of three input ports for Science Operations Plan
implementation of tour sequences S09 and S10 was reached this week. The
merged product was handed off to ACS for end-to-end pointing profile
validation. The final input port also closed this week for the Science
Planning Team development of the C34 sequence. This merged product was
also delivered to ACS for end-to-end pointing profile validation.

Uplink Operations presented requirements for Target Options and Modules
scheduled for Mission Sequence Subsystem D9.0 at this week’s Cassini
Design Team meeting.

Outreach gave a series of presentations on the Cassini mission, and
presented educator activities to 30 classroom educators participating in
a 2-week NASA Educator Workshop (NEW).

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.

SpaceRef staff editor.