NASA Cassini Significant Events for 08/26/04 – 08/31/04

The most recent spacecraft telemetry was acquired from the Madrid tracking
station on Tuesday, August 31. 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
http://saturn.jpl.nasa.gov/operations/present-position.cfm .

Last week Cassini passed apoapsis, the farthest point from Saturn in its
orbit, and in this case, in the entire tour.  It also marked the transition
between Rev 0 and Rev A – Rev being another term for orbit – and marks the
start of Cassini’s approach to Titan for the Titan-a encounter in October.
At its present position, Cassini is outside Saturn’s magnetosphere.  From
this vantage point the Magnetospheric and Plasma Science (MAPS) instruments
continued their campaign to study the influence of the solar wind on
Saturn’s aurora. The combination of this large distance and the quality of
the imaging subsystem allows an opportunity to obtain mosaics and movies
over large areas that will be used to study storms and dynamics in Saturn’s
atmosphere.

This week the optical remote sensing (ORS) instruments scanned Saturn’s
south pole, obtained ultraviolet mosaics of Saturn’s magnetosphere, and
observed Saturn’s aurora. The imaging cameras obtained mosaics and movies of
the rings and Saturn’s south pole, and the Magnetospheric Imaging Instrument
(MIMI) imaged the magnetosphere and observed the solar wind and pickup ions.

Additional activities included uplink of a file to activate an internal
sequence for the Cosmic Dust Analyzer, and a time-of-flight unit tweak for
the Cassini Plasma Spectrometer to obtain higher resolution data during
their upcoming calibration.

Spacecraft Operations Office activities this week included a reaction wheel
assembly friction test on board the spacecraft, and a test of Orbit Trim
Maneuver 003 (OTM) in the Integrated Test Laboratory. The results from the
friction test are being analyzed currently.  Friction tests are performed
every three months on the prime wheels 1,2 and 4 to trend their performance.
OTM-3 will be tested twice, once using the Reaction Control Subsystem and
the second time using the main engine.  The benefit of using the main engine
for such a short burn – approximately 3 seconds – is that it allows the
program to conserve the hydrazine propellant.

The Section 312 Navigation Advisory Group conducted a review of the
Project’s planning and preparation for the Huygens Probe mission activities.
The board report is not available yet, but comments during the course of the
review were generally favorable.

The sub-sequence generation products were delivered to the program file
repository in support of sequence development for S05.  In addition, a
meeting was held to discuss simulation requirements for Titan-a Integrated
Test Laboratory testing.

The Mission Sequence Subsystem (MSS) team released MSS D11 baseline plans
for Project review at a Cassini Design Team meeting this week.  At the same
time, a discussion was held for plans and proposed features for MSS D10.3.2,
D10.3.3 and D10.4 deliveries prior to the Probe Mission and leading up to
the D11 delivery in April of next year.
For the most recent Cassini information, press releases, and images, go to
http://saturn.jpl.nasa.gov .

The Cassini-Huygens mission 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, manages the
Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington,
D.C.  JPL designed, developed and assembled the Cassini orbiter.