Cassini Update - July 3, 2003

Cassini Significant Events
for 06/26/03 - 07/01/03

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Tuesday, July 1. 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/operation...t-position.cfm .

On July 1, Cassini was exactly one year away from Saturn Orbit Insertion
(SOI). Next year the spacecraft will complete a 6.7-year interplanetary
journey, and begin orbital operations.

On board activities this week included clearing of the ACS high water
marks, Radio and Plasma Wave Science (RPWS) High Frequency Receiver
calibrations, and an RPWS periodic instrument maintenance. This week
Cassini passed through a Sun - Earth - Probe angle of 4.0 degrees down
to minimum separation of 0.344 degrees. When the separation angle
reached about 3 degrees, the project began uplinking a command file
consisting of 10 no-op commands sent every 5 minutes. The file is
uplinked 10 to 20 times daily. These commands have been sent to the
spacecraft each time Cassini enters Solar Conjunction. The purpose of
the test is to accumulate statistics for uplink reliability at decreased
separation angles. SOI will occur on July 1, 2004, and conjunction will
follow within 7 days. Knowledge of how conjunction affects commanding
will be crucial at that time.

Radio Science Subsystem (RSS) personnel continue to concentrate on
characterizing the anomalous behavior of the Ka-Band Translator (KaT)
for the on-going Solar Conjunction Experiment #2. The KaT continues to
operate in its bad region.

Simulation coordination meetings for C39 were cancelled after it was
determined that activities in the background sequence did not require
Integrated Test Laboratory (ITL) testing. Trajectory Correction
Maneuvers (TCM) 19a and 19b which occur in this sequence will be tested
separately as mini-sequences.

Events this week for the S14 Science and Sequence Update Process (SSUP)
Verification and Validation (V&V) activity included release of merged
product review reports generated by the Spacecraft Operations Office
(SCO), Science Planning, and Uplink Operations (ULO), release and review
of an updated reference trajectory, execution of the file configuration
management process, and delivery of 12 sequence change requests and
review comments for the Preliminary Sequence Integration and Validation
1 phase.

SCO completed a ten-day test in the ITL of the C38 SOI Critical Sequence
demonstration on July 1, exactly one year before the real SOI. The C38
SOI Critical Sequence demo will be performed on the spacecraft July 21 -
August 4, 2003.

The Navigation Team has completed and documented the reconstruction of
TCM 19. The results continue to indicate that the maneuver executed as
planned with sub-sigma errors.

Two delivery coordination meetings were held this week, one for a Deep
Space Mission System (DSMS) delivery of the Telecom Forecaster/Predictor
(TFP) V 3, and the second for the Radio Science Subsystem (RSS) LMBTRK
version 1.1, and an engineering version of BISTAT. The delivery of TFP
provides upgrades to the DSN configuration models, as well as a few
minor GUI changes. A full regression test with the previous version V2.1
showed no problems. LMBTRK is the RSS program that generates the
Inertial Vector Definition (IVD) file used as input to the Pointing
Design Tool (PDT) for generating spacecraft pointing commands during RSS
occultations. BISTAT also generates an IVD file used as input to PDT,
but it is optimized for RSS bi-static radar experiments.

Cassini Outreach conducted Solar System Ambassador training on Saturn's
Rings, and gave an overview of Cassini's outreach opportunities.
Approximately 50 members of JPL's Solar System Ambassador program
attended.

A 2-day meeting of the K-4 education literacy partnership was held at UC
Berkeley. Lesson units were reviewed, and organizational issues were
addressed as the team moves toward a January 2004 final product
delivery.

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.

Cassini Outreach
Cassini Mission to Saturn and Titan
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration

wrote in message
...
In sci.astro Ron Baalke wrote:

Cassini Significant Events
for 06/26/03 - 07/01/03

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Tuesday, July 1. The Cassini spacecraft is in an
excellent state of health and is operating normally.

Didn't you already post this last week?

That was last weeks update

this is dated July 3rd - that was dated June 27th.

Ron's been faithfully delivering these just about every week since October
1997!

Doug

(Ron Baalke) wrote in news:be21ol$9hk$1
@nntp1.jpl.nasa.gov:

Radio Science Subsystem (RSS) personnel continue to concentrate on
characterizing the anomalous behavior of the Ka-Band Translator (KaT)
for the on-going Solar Conjunction Experiment #2. The KaT continues to
operate in its bad region.


A few questions for a (patient) Cassini communication expert.

What's wrong with the Ka-band translator? Does anyone know -- beyond the
fact it is in the "bad zone"? How does this affect radio communication?
Will it impact the amount of info returned by the mission? Can X-Band do
the job if KA band doesn't work?

Seems to be a history of power problems with this device. It was doing
funny things from time to time when the power to the S-Band transmitter
was turned on. What could the link be?

Thanks
Mark