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Cassini Significant Events
for 04/03/03 - 04/09/03

The most recent spacecraft telemetry was acquired from the Canberra
tracking station on Wednesday, April 9. 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 .

Command and Data Subsystem (CDS) Flight Software (FSW) checkout
activities continued this week with an Instrument Expanded Block
(IEB) load to the SSR library region. This procedure uplinks and
stores IEBs in the new Version 9.0 Library region. The Library Region
is a new sub-partition on the SSR that allows instruments or
subsystems to store frequently used commands on the SSR for an
extended length of time. When needed, a single command will load this
data from the Library region to the instrument for execution. This
procedure loaded and verified that Instrument IEBs were loaded into
the Library region successfully. 

After the IEB load, the CDS Command Loss Timer threshold value was
set to 2 days, and a High Gain Antenna (HGA) response checkout was
performed. The purpose of this procedure was to demonstrate that the
new System Fault Protection algorithm called the HGA Response will
change the uplink data rate to 250 bps, and the downlink telemetry
mode to RTE-1896, as well as the proper execution of the 7SAFE,
iOTHERi response.  This procedure was clean and successful, thanks to
all the support from Systems, Attitude Control Subsystem (ACS),
System Fault Protection, Telecom and others.

Following the HGA checkout, the ACS High Water Marks were cleared,
CDS Background Sequence #2 uplinked, CDS Command Loss Timer threshold
returned to the nominal 11 day value, and a Probe Solid State
Recorder dual record demo was begun. This will be the first in-flight
demonstration of the Probe Relay telemetry mode with dual SSRs.

A simulation procedure review meeting was held for C37 as part of the
sequence development process. Testing in the Integrated Test
Laboratory for the C37 background sequence and Trajectory Correction
Maneuver 19 began this week and continues to the weekend.

A wrap-up meeting was held for Science Operations Plan (SOP)
implementation for tour sequences S15/S16. The sequences will now be
archived until June of 2005 when SOP Update, and the Science and
Sequence Update Process will begin.

The S17/S18 preliminary port#3 inputs have been delivered.  A data
volume problem occurring on two days was identified, and later
resolved at the weekly Tour Process meeting.

The C38 Science Planning Team process kicked off this week.
Development of this sequence will use a compressed five week
schedule, and completes in early May.

SOP Update Verification and Validation (V&V) using S14 continued this
week.  Cassini Information Management System (CIMS) change requests
were published to identify changes the teams need to make to their
CIMS requests. Mission Sequence Subsystem developers provided user
support for D9.0 PDT and SEQ_CONVERT during the on-going V&V
exercise. 

Mission Planning presented the results of the extended mission
planning and budget task.  Budget and workforce estimates were
delivered along with a final implementation schedule.

System Engineering is leading preparation for the Approach
Science/Tour Operations Readiness Review to be held in October of
this year.  A requirements and capabilities table organized by
Operations Concept has been generated and is being reviewed by the
Teams/Offices. 

In last weeks Significant Events report, an incorrect ULR was listed
for the Kids' section of the Cassini website.  The correct URL is
http://saturn.jpl.nasa.gov/kids/index.cfm

University of Hawaii astronomers formally announced the discovery of
the first new satellite of Saturn in three years at the International
Astronomical Union on April 8, 2003. The satellite has a distant
retrograde orbit, and is about 8 km in diameter.  For more
information go to

http://www.ifa.hawaii.edu/~sheppard/satellites/sat2003.html

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

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