Trajectory Adjustment Prepares Cassini for Second Venus Flyby
December 3, 1998
NASA's Cassini spacecraft successfully completed a long-planned 90-minute firing of its onboard rocket engine late last night, setting the spacecraft on course for a second flyby of Venus -- the next major milestone on Cassini's long trajectory to Saturn.
The main rocket engine firing started at 10:06 p.m. Pacific time and ended at 11:36 p.m. for the so-called "deep space maneuver" that put the spacecraft on course for its next planetary gravity-assist - a flyby of Venus next June.
"The performance of the spacecraft and the team in performing this maneuver was just perfect, we couldn't have asked for anything better," said Bob Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. Since its flawless launch Oct. 15, 1997, Cassini's flight has been characterized by excellent performance and extraordinary accuracy in navigation.
Telecommunications with Cassini throughout the maneuver were conducted through NASA's Deep Space Network complex near Madrid, Spain. Mission engineers said the engine firing went exactly as planned, slowing the spacecraft by close to 450 meters per second (about 1,006 miles per hour) relative to the Sun. Cassini's speed went from 67,860 kilometers per hour (42,168 miles per hour) at the start of the maneuver to 66,240 kilometers per hour (41,161 miles per hour) at the end of the engine firing. The maneuver adjusted the angle of the spacecraft's flight path relative to Venus' orbit so that Cassini will achieve the maximum velocity boost from Venus' gravity during the June flyby of that planet.
Last night's engine firing is one of two long burns of the engine over the entire course of the mission; when Cassini reaches Saturn in July 2004, the engine will burn for about the same amount of time to brake the spacecraft into orbit around the ringed planet.
All of Cassini's systems remain in excellent condition. The spacecraft has flown more than 1.055 billion kilometers (655.5 million miles) since launch. Cassini, a joint mission of NASA, the European Space Agency and
the Italian Space Agency, will orbit Saturn for four years and drop a scientific probe through the atmosphere and to the surface of Saturn's largest moon, Titan. For more information, see
JPL, a division of the California Institute of Technology, Pasadena, CA, manages the Cassini program for NASA.
Additional information about Cassini-Huygens is online at http://saturn.jpl.nasa.gov.
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.