Significant Event Report for Week Ending 6/8/2001

Cassini Significant Event Report

For Week Ending 06/08/01

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Wednesday, June 6. 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 included an Attitude Control Subsystem (ACS)
high water mark clear, a CDS error log clear, a Reaction Wheel Assembly
(RWA) momentum unload, and an ACS Catbed Heater test. For this test the
heaters on both thruster branches were powered on to verify that the SCO
thermal heating model was correct. The test executed nominally. In
addition, the Radio Frequency Subsystem began solar conjunction testing.
The tests began on Thursday May 31 and will continue through the end of
superior conjunction in the first week in June. For these tests commands
are uplinked at 250 and 500 bits per second. The results will help the
Spacecraft Operations Office (SCO) plan for Saturn Orbit Insertion, which
occurs near superior conjunction.¿

Sequence development is under way for the Probe S-band carrier signal test
to be carried out during C26 in mid June. All inputs from SCO, RSS and
the Probe have been received. The sequence products will be released for
review at the end of this week with a command approval meeting set for the
following week.

The Huygens Recovery Task Force held a two day meeting in Noordwijk, the
Netherlands. Excellent progress is being made in finding a solution for
the relay link problem, and a summary report will be made to the full PSG
at the Oxford meeting later this month.

The C28 SPVT Project Briefing was given by Science Planning. The project
has approved the integrated plan for implementation. Science turns on
thrusters needed to accomplish interplanetary cruise fields and particles
data collection will be performed at slower turn rates in order to
minimize hydrazine usage. The current sequence has four 90 degree and one
<1 degree turns on thrusters to accomplish these measurements.

Working group meetings and telecons were held for the Titan Orbiter
Science Team (TOST), the Satellite Orbiter Science Team (SOST), the
Atmosphere Working Group (AWG), and the Rings Working Group (RWG). The
TOST focused on finalizing the integration of the first 10 Titan flybys
and preparation of the TOST report to the Planetary Science Group (PSG).
The TOST is looking for PSG approval of these plans at the Oxford meeting
to be held on June 18-22.¿

Instrument Operations (IO) and the Multi Mission Image Processing
Laboratory processed and delivered 238 ISS Photometric Calibration and
Dark Frame images produced in the C26 sequence.

Mission Planning activities this week included kick off of a task to
assemble and manage the propellant budget for cruise and tour, completion
of Revision M of the Mission Plan, and publication of the "Mission Plan
Quick Reference Guide." The reference guide is being published for the
first time and is a very useful document providing all the updated tables
and charts from revision M of the Mission Plan. Both documents will soon
be available from the Cassini Electronic Library (CEL).

Mission Assurance and Systems Engineering signed off the updated Anomaly
Reporting Plan. This plan documents the process by which Cassini uses the
Institutional Problem Reporting System for anomaly documentation,
resolution, corrective action, and verification. The Program recently
approved changes to the existing process and has begun using the updated
process.¿

Revision G of the Cassini Anomaly Response Operations Plan has been signed
off. The document will be available from the CEL next week.

More than 20 scientists presented preliminary results from last winter's
Jupiter flyby during meetings of the American Geophysical Union in Boston
this week. Among them were sixteen scientific papers about Cassini
results from that encounter. Cassini flew past Jupiter in December 2000
for a gravity assist to reach Saturn. Researchers took the opportunity to
study the giant planet from different vantage points by also using NASA's
Galileo spacecraft, plus other spacecraft and ground-based telescopes, in
coordination with Cassini's Jupiter observations. A list of the papers
presented is available at

HREF="http://agu.org/cgi-bin/sessions?meeting=sm01&part=P51A&maxhits=100">http://agu.org/cgi-bin/sessions?meeting=sm01&part=P51A&maxhits=100

More information about the joint Cassini and Galileo studies of Jupiter is
available at http://www.jpl.nasa.gov/jupiterflyby .

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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