Status Report

Cassini Significant Events for 07/25/02 – 07/31/02

By SpaceRef Editor
August 3, 2002
Filed under , ,

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Tuesday, July 30. 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 .

On board activities this week included uplink of real-time commands to
read out data from the AACS Stellar Reference Unit table, and clear the
AACS High Water marks. Additional instrument activities included
calibrations of the Radio and Plasma Wave Science (RPWS) High Frequency
Receiver, Ultraviolet Imaging Spectrograph (UVIS) periodic instrument
maintenance, and instrument flight software normalization for RPWS and

The data from the 2002 Solar Conjunction Experiment performed in June
and July have been processed, and preliminary analysis shows a
successful investigation, despite initial problems with the ground
instrument. An estimation of the effect has been determined and will be
refined as the data are calibrated further.

One of the goals of the Cassini Solar Conjunction Experiment is to
measure the effect of the solar gravity on the path of electromagnetic
radiation. Propagating photons of the radio signal are deflected and
delayed by the sun. Predicted by Einstein in 1916, this was measured
during a solar eclipse in 1919 as the first experimental test of General
Relativity. A violation of General Relativity might be due to scalar
fields remnant of the Big Bang, and its detection would have crucial
implications in physics. Cassini can measure the gravitational
deflection utilizing a highly accurate Doppler system at X- and
Ka-bands, potentially to a level of one hundred times better than past

The Multi-mission Image Processing Laboratory software version 28 was
installed for operations use this week. This delivery supports Cassini
cruise and is the first of three phased implementations to include
support for tour. Also included are ground processing updates to
support changes to VIMS flight software, Video Information Communication
and Retrieval multi-mission routines for project recognition, and label
decoding and camera parameter updates to support Cassini. With this
change, Cassini gains access to numerous image analysis tools.

Instrument Operations (IO) personnel attended a Planetary Data System
(PDS) Management Council meeting. Cassini archive status was presented,
and a discussion held on archive challenges from a project point of
view. PDS provided a demonstration of the new PDS archive and
distribution system. The IO representative was very impressed and
recommended a demonstration also be given at the next Cassini Project
Science Group Meeting to be held at JPL in October 2002.

During the transition from reaction wheel to thruster control last week,
the Attitude Control team used the opportunity to perform a friction
test on the reaction wheels. The test carefully examined the "spin down"
characteristics of each of the wheels. The team has processed the data
and concluded that the reaction wheels are continuing to perform

A series of meetings has been held to plan the implementation of
Prime/Rider instrument coordination within Cassini. The preliminary
results will be presented at next week’s Instrument Operations Working
Group meeting.

Uplink Operations hosted an SSR Management Tool (SMT) development
meeting to work with the Spacecraft Office (SCO), Science Planning, and
Mission Planning on determining what updates will be included in the
D9.0 delivery of SMT.

System Engineering (SE) has completed work with the SCO CDS Team to
clean up the flight rule (FR) allocation matrix, prioritize FR fixes in
software, and review the sequence checklist. Similar activities for the
remaining SCO subsystems are in work. In addition, SE presented a
proposal for Level 4 Verification and Validation plans at the System
Engineering Round Table meeting.

Mission Assurance convened a quarterly Risk Team meeting to assess the
remaining six cruise risks as well as risks associated with the Huygen’s
Probe mission. Several new risks were identified, existing risk
descriptions were refined, and action was taken by the Spacecraft Office
to rework Probe Mission risks completely. Quarterly meetings are part of
the on-going Risk Management process on Cassini during Flight

The Cassini Program Outreach Team has selected a vendor to produce the
planetarium show "RingWorld." The show will debut in January 2003.
Produced in multiple formats, it will be made available to over 950
planetariums in the USA, as well as community colleges, schools, youth
groups, and online via the Cassini web site. A Spanish language
translation of this show will also be produced. A portion of the show
will talk about the Deep Space
Network. The DSN will cost share and place a copy of this show in their
visitor centers in Australia, California, and Spain.

Cassini Outreach has updated the Titan Landing Site graphic to reflect
the new landing site and date for the Huygens Mission. This new graphic
has a reference number of P-50940, and is available through
Finley-Holiday at</a> or by calling
(800)345-6707. The image will be placed on the gallery portion of the
Cassini web site, and will also be part of Huygens related slide sets.

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.