Cosmic Dust Analyzer Activated

April 5, 1999

The Saturn-bound Cassini spacecraft remains in excellent health and on-course for the second of its two flybys of the planet Venus in June. The spacecraft's nearly seven-year flight path also includes one flyby of Earth and one of Jupiter, with the gravity of each of those planets imparting speed to the spacecraft so it can reach Saturn in 2004.

On Monday, March 22, an update to the software for Cassini's cosmic dust analyzer was radioed to the spacecraft through NASA's global Deep Space Network telecommunications system. Two days later, the instrument was successfully turned on as planned and the telemetry rate was changed to allow the return of scientific data from the dust analyzer.

The cosmic dust analyzer, one of 12 experiments on the Cassini orbiter, will help to determine the density and composition of Saturn's rings. The instrument has two types of sensors -- high-rate detectors and a dust analyzer. The two high-rate detectors are intended primarily for measurements while Cassini is in Saturn's rings, where the dust analyzer will count up to 10,000 impacts per second. The dust analyzer determines the electric charge carried by dust particles, their flight direction and impact speed. It also provides measurements of particle mass and chemical composition. Dr. Eberhard Grun of the Max Planck Institute fur Kerphysik, Heidelberg, Germany, is the principal investigator of the experiment.

Currently, most activity with the Cassini spacecraft is devoted to routine maintenance of the spacecraft systems, with communications directed through the antennas of NASA's Deep Space Network. Cassini is more than 132 million kilometers (82 million miles) from Earth, traveling at a speed of about 91,500 kilometers per hour (about 56,800 miles per hour). It has traversed more than 1.27 billion kilometers (about 789 million miles) since launch Oct. 15, 1997.

The Cassini/Huygens mission to Saturn and Titan, a joint project of NASA, the European Space Agency and the Italian Space Agency, is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL is a division of the California Institute of Technology.

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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