The flight team for NASA's Jupiter-orbiting Galileo spacecraft will cease operations on Friday, Feb. 28 after a final playback of scientific data from the robotic explorer's tape recorder.
The team has written commands for the onboard computer to manage the spacecraft for its short remaining lifetime. Galileo will coast for the next seven months before transmitting a few hours of science measurements in real time, leading up to a Sept. 21 plunge into Jupiter's atmosphere.
"This mission has exemplified successful team efforts to overcome obstacles to make outstanding discoveries," said Dr. Eilene Theilig, Galileo project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "While the team is sad to see it come to an end, there is great pride in Galileo's remarkable accomplishments."
In the years since astronauts deployed Galileo from the cargo bay of Space Shuttle Atlantis in 1989, the mission has produced a string of discoveries about asteroids, a fragmented comet, Jupiter's atmosphere, Jupiter's magnetic environment, and especially about the geologic diversity of Jupiter's four largest moons. The prime mission ended six years ago, after two years of orbiting Jupiter. NASA extended the mission three times to continue taking advantage of Galileo's unique capabilities for accomplishing valuable science.
Now, the onboard supply of propellant is nearly depleted. Without propellant, the spacecraft would not be able to point its antenna toward Earth nor adjust its trajectory, so controlling the spacecraft would no longer be possible. Before that could happen, the flight team last year put Galileo on course for disposal by a dive into the crushing pressure of Jupiter's atmosphere. This strategy eliminates any possibility of an unwanted impact between the spacecraft and the moon Europa. Galileo's own discovery of a likely subsurface ocean on Europa has raised interest in the possibility of life there and concern about protecting it.
On Nov. 5, 2002, the orbiter passed closer to Jupiter than it had ever ventured before, flying near an inner moon named Amalthea and through part of Jupiter's gossamer ring to begin its 35th and last orbit around the giant planet. This elongated farewell loop will take Galileo farther from Jupiter than it has been since before it entered orbit in 1995, to a point more than 26 million kilometers (16 million miles) away on April 14 before heading back in for impact.
Scientific data recorded on the tape recorder during last November's flyby have been gradually played back for transmission to Earth since the flight team repaired radiation damage to the tape recorder in December. Transmissions during a communication session with a NASA Deep Space Network antenna at Goldstone, Calif. Thursday night and early Friday will finish the playback.
"After this month, we have no further activities planned until the day of impact," Theilig said.
The Galileo flight team numbered about 300 people at its peak during the prime mission, but has run much leaner in recent years, with about 30 since the Amalthea flyby. That smaller team is now disbanding, mostly to work on other JPL-managed NASA missions that are in development or already flying.
JPL, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about the mission and its discoveries is available online at http://galileo.jpl.nasa.gov.