NASA Cassini Significant Events for 11/11/04 – 11/17/04

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

Science activities this week began with images taken of newly discovered
moons by the Imaging Science Subsystem (ISS). The Ultraviolet Imaging
Spectrograph (UVIS) continued obtaining mosaics to determine the density of
neutrals in the inner magnetosphere. While inside the magnetosphere, the
suite of Magnetospheric and Plasma Science (MAPS) instruments continued its
magnetospheric boundaries investigation in the dawn sector at southern
latitudes and at a variety of radial distances. Once outside of the
magnetosphere, the instruments monitored the solar wind.

The Titan Atmosphere Model Working Group met in Pasadena, CA this week to
discuss instrument measurements and ACS results from the Titan-a flyby.
Although the flyby occurred less than a month ago, all applicable data was
processed in time for the meeting as promised. Key results were:

• No significant argon in Titan’s atmosphere.
• Methane abundance is 1.8% +0.5%.
• CIRS and INMS density values are consistent with post-T0 models.

S05 activities concluded this week with the radiation of Reaction Wheel
Assembly (RWA) bias commands that will execute in S06, along with the
radiation of the S06 Instrument Expanded Blocks and background sequence.

S06 began execution on Monday November 15, and runs for 31 days until
December 16. During this sequence the flight team will support two Orbit
Trim Maneuvers – #6 and #7 -, the Titan-b flyby on December 13, a Dione
flyby on December 15, and uplink a live Inertial Vector Propagator (IVP)
update. During S06, the DSN will support the program with 38 station
passes, 16 of which will be over 70 meter antennas.

A Huygens Playback Meeting was held to review the ground system processes
for support of Probe Checkout F16. The focus was on processed telemetry
receipt and data transfer to the Huygens Probe Operations Center in
Darmstadt, Germany. A follow-up meeting will be held next week.

Initial activities in S06 included an RWA bias, uplink of the Probe Checkout
mini-sequence, and uplink of some testing files for the Cassini Plasma
Spectrometer.

Although execution of S06 has begun, some items are still in development.
The sequence development leads have laid out and distributed a schedule for
the Titan-b live IVP update. The Titan Orbiter Science Team /Science Team
responsibility for a live update is to take the new trajectory delivered by
the Navigation team and determine if the live update is still required to
meet designs and present this at a "GO/NO-GO" meeting. For the Phoebe live
update a single driving instrument did this work, but it was determined that
science participation by any instrument that cares about the details of
PRIME pointing was more useful. The process will kick off on November 19, a
go/no go meeting will be held on November 22, and if approved, a command
approval meeting will be held on November 30.

Sequence development is ongoing for tour sequences S06 through S12, and S37
through S41.

Science Operations Plan (SOP) implementation of S41 – the final sequence in
Cassini’s prime mission – began this week.

Requested changes to S12 were due this week prior to next week’s assessment
meeting and kick off of the Aftermarket process.

Teams made the official port 2 delivery for the S09 SOP Update process.

Sequences S07 and S08 continue in the Science and Sequence Update Process
(SSUP). This is the final process prior to sequence execution. A
Preliminary Sequence Integration and Validation (PSIV) Sequence Change
Request approval meeting was held for S07. Ten changes were approved and
one withdrawn. In addition, stripped files were distributed back to
participating teams for the PSIV2 portion of the process. For S08, the
merged background sequence and SEG products were released as part of PSIV1.

A delivery coordination meeting was held for new a version of the Radio
Science Subsystem (RSS) programs PREDICTS, LMBTRK, and BISTAT. New versions
of the software were delivered to the Program Software Library for archive
and will become operational to support RSS operations.

The PREDICTS software computes the expected received frequencies as a
function of time. It generates a Downlink Frequency File (DLF), which is an
input file to the Radio Science Receivers at the DSN stations.

The LMBTRK software computes the direction at which a radio signal must be
sent in order to reach the ground station after traversing an atmosphere.
It generates an Inertial Vector Definition (IVD) file, which is an input to
the Pointing Design Tool.

The BISTAT software computes the direction at which a radio signal must be
sent in order to reach the ground station after bouncing off a planetary
body. It also generates an IVD file.

Cassini outreach attended a special showing of the Cassini "Ring World"
planetarium show in the Rauch Planetarium, Gheens Science Center, University
of Louisville, and attended a second show plus public star party for the
local cub scouts. Ring World is available as part of the school group show
library at the planetarium.

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.