Cassini Program Status Report

March 1, 1996

The University of Iowa's Radio and Plasma Wave Science Subsystem (RPWS) became the first science instrument to be installed on the Cassini spacecraft last month while several other instruments from other institutions around the country arrived at JPL for test and integration onto the Saturn-bound spacecraft. RPWS data will be used to determine the planet's rotation rate and help characterize Saturn's interior, magnetic field, lightning and the planet's interaction with charged particles flowing from the Sun.

After the RPWS integration, the Cassini Ground System successfully supported the first operational transfer of data from the instrument to the principal investigator's site at the University of Iowa. This new method, using the Science Operations and Planning Computer (SOPC) provided by the Distributed Operations Interface (DOI) Element, allows the science team for each instrument to remotely control, test and receive data from their instrument without leaving their home institution, resulting in significant cost and time savings to the program.

Instruments delivered to the Cassini Program last month included the Composite Infrared Spectrometer (CIRS) from the Goddard Space Flight Center; the Imaging Science Subsystem (ISS) from JPL, the UVIS from the University of Colorado, Boulder, the Magnetospheric Imaging Instrument Subsystem (MIMI) from Applied Physics Laboratory of Johns Hopkins University, and the Magnetic Field Investigation (MAG) from the Imperial College of Science and Technology in London, England.

The Cosmic Dust Analyzer (CDA) Engineering Model (EM) Instrument completed qualification thermal vacuum testing at
Heidelberg, Germany. The Cassini Radar Subsystem (RADAR) Digital Assembly (DSS) successfully passed protoflight vibration testing.

The Attitude and Articulation Control Subsystem/AACS Flight Computer (AACS- AFC) A/B side integration has been completed. The integration of the engineering model (EM) Propulsion Module Subsystem, Electronics Assembly (PMSEA) with the A side Valve Drive Electronics has been completed. The B side is in process.

The Radio Frequency Subsystem (RFS) has successfully completed all system integration and capability tests with the Deep Space Network (DSN) and is being prepared for electromagnetic compatability and interference tests.

The Propulsion Module Assembly was completed and successfully underwent tests to ensure it was leak-proof.

In Europe, work on the Huygens Probe progressed with the integration of the Descent Imager Spectrometer Radiometer (DISR), the Aerosol Collector Pyrolyser (ACP), the Huygens Atmospheric Instrument (HASI), the Surface Science Package (SSP), and the Command and Data Management Unit (CDMU).

In the area of mission science planning, the world's experts on planetary rings met last month to discuss ring particle distribution estimates to be used by Cassini trajectory designers to specify a safe flight path during the spacecraft's four-year orbital tour of the Saturn system. The program also approved a minimum flyby altitude of Saturn's moon Titan of 950 kilometers, (about 590 miles) except for six passes that could have altitudes as low as 850 km (about 530 miles) for data gathering by the Ion and Neutral Mass Spectrometer (INMS).

Cassini-developed technologies and management approaches being used by other projects made news in the past month, among them;

  • The Near Earth Asteroid Rendezvous (NEAR) spacecraft was successfully launched, carrying the Cassini-developed Deep Space Transponder (DST), Command Detector Unit (CDU) and the Inertial Reference Unit (IRU).

  • The Mars Pathfinder spacecraft, which uses Application-Specific Integrated Circuits (ASICs) and a micro-miniature radio transponder developed by the Cassini Program, was readied for final thermal-vacuum testing last month prior to shipment to Cape Canaveral for launch later this year.

  • The Mars Volatiles and Climate Surveyor (MVACS) Project has decided to use the Receivable/Deliverable portion of the Cassini Management Information System (CMIS), which has been of critical importance in keeping the program on schedule and under budget.

Several instrument deliveries and integrations are scheduled for Cassini this month. The spacecraft will be shipped to Cape Canaveral, FL, in late April 1997 for an October 1997 launch.

Additional information about Cassini-Huygens is online at

Cassini will begin orbiting Saturn on July 1, 2004, and release its piggybacked Huygens probe about six months later for descent through the thick atmosphere of the moon Titan. Cassini-Huygens is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Office of Space Science, Washington, D.C.

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