SwRI scientists play role in Cassini mission

Two SwRI-developed instruments fly aboard Cassini rocket's Saturn mission

San Antonio, Texas -- October 10, 1997 -- When the Cassini-Huygens spacecraft lifted from Cape Canaveral on a seven-year voyage to explore Saturn, the school bus-size craft's payload will include two instruments to be operated by scientists at San Antonio-based Southwest Research Institute^® (SwRI^®).

Dr. David T. Young is the principal investigator for the Cassini Plasma Spectrometer (CAPS), and Dr. J. Hunter Waite Jr. is the facility team leader for the Ion Neutral Mass Spectrometer (INMS). Young and Waite are Institute Scientists in SwRI's Instrumentation and Space Research Division.

CAPS, consisting of three electron and ion sensors, was developed by SwRI and an international team of scientists headed by Young. The sensors are designed to determine the composition, dynamics, and temperature of the plasma that surrounds the Saturn system, giving information that will help to characterize the evolution of the Saturn system over its 4.5 billion-year existence.

The INMS, built at the National Aeronautics and Space Administration's Goddard Space Flight Center, will be scientifically operated by an international team of scientists headed by Waite. It will return information on the composition and thermal structure of the atmosphere and ionosphere of Saturn's largest moon Titan, and of Saturn's rings and icy satellites.

This composition information is important in determining the chemical processes that shape the Saturn environment. Of particular interest is the complex carbon-nitrogen chemistry that is initiated by energetic particles and solar ultraviolet light in the upper regions of Titan's nitrogen-methane atmosphere. This chemistry is responsible for the complex compounds observed in the clouds and lower atmosphere, and also for producing tars and ponds of liquid ethane that cover a portion of Titan's surface. It is thought that the rich organic chemistry in this oxygen-poor environment, cold and without liquid water, forms the compounds that could eventually become the building blocks of life.

In addition, Cassini carries 10 other instruments to image the Saturn system at infrared, ultraviolet, and visible wavelengths, and to directly sample the dust, neutral and charged particle environment.

The Cassini spacecraft also carries the Huygens probe, built by the European Space Agency. Huygens consists of six experiments to measure Titan's composition, temperature, and the dynamics of its atmosphere, to determine the makeup of the enveloping cloud cover, and to perform multi-spectral imaging of Titan. Shortly after Cassini enters orbit around Saturn in July 2004, Huygens is to separate from the spacecraft and parachute to a soft landing on Titan.

Before that happens, however, seven years will have passed. The "Year 2000" computer problem will have been long resolved, and the United States will be in its second presidential campaign since Cassini's launch. The SwRI science team won't be idle in the interim. It must develop the onboard and ground software that will guide the robotic sensors and facilitate interpretation of the measurements during four years of data acquisition within the Saturn system.

The team's scientists will also be carrying out initial testing to verify the instruments' inflight performance, and participating in science planning to maximize the scientific return of the mission.

For more information about SwRI's role in the Cassini mission, contact Joe Fohn, Communications Department, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, Phone (210) 522-4630, Fax (210) 522-3547.

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