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Cassini Significant Events
for 04/24/03 - 04/30/03

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

April 26th marked the 5th anniversary of Cassini's first Venus flyby.
Cassini is using a Venus-Venus-Earth- Jupiter trajectory. Each flyby
provides a gravity assist that cumulatively will enable Cassini to
reach Saturn in 2004.

The Command and Data Subsystem (CDS) Flight Software (FSW) checkout
concluded this week with a successful optical navigation (OPNAV)
test. Final activities for C36 included a reaction wheel assembly
momentum unload, and uplink of the C37 background sequence.

The completion of the optical navigation test marks the conclusion of
the engineering flight software checkout period. Both the Attitude
Control and Command and Data subsystems have successfully
demonstrated the full suite of capabilities afforded by the new
software that will be used throughout orbital operations.

C37 began execution late Monday night.  Initial activities included
loading of Imaging Science Subsystem (ISS), Ultraviolet Imaging
Spectrograph (UVIS), and Radio and Plasma Wave Science (RPWS)
instrument expanded blocks from the background sequence, RPWS
high-rate observations, an RPWS high frequency receiver calibration,
and clearing of the attitude control high water marks.  At the end of
this week the spacecraft transitioned to reaction wheels in
preparation for trajectory correction maneuver 19.

Optical navigation data from this weeks test have been processed by
the Multimission Image Processing Laboratory (MIPL), including 18
Narrow Angle Camera (NAC) and nine Wide Angle Camera (WAC) images.
The Navigation team has reviewed the data and reported that pointing
was very good (within about five or six NAC pixels of the target) and
that the exposures on 11th magnitude stars are good.

Mission Planning and Science Planning held a kick off meeting for the
implementation of the science operations plan for tour sequences tour
sequences S7/S8 this week, along with a project briefing for the
cruise sequence C39.

An Archive Design Peer Review of the Cosmic Dust Analyzer (CDA), ISS,
Radio Science Subsystem (RSS), and Visual and Infrared Mapping
Spectrometer (VIMS) instrument team archive plans was held this week.
Members of the Planetary Data System, instrument team
representatives, and Instrument Operations personnel attended.

A Software Review Certification Requirement meeting was held for
Composite Infrared Spectrometer FSW version 2.0.1.  The software is
due to be uplinked to the spacecraft in late May.

MIPL delivered an engineering version of the remote constraint
checker tools to the ISS and VIMS science teams.  The software will
be used for validation of Instrument Operations Interface (IOI) files
prior to delivery to IO.  These tools allow a remote site to
automatically deliver preliminary IOI files to MIPL, have them
error/constraint checked there, and have the results returned to the
remote site.  During operations this will enable instrument teams to
deliver error-free IOI files.

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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