Volume: 01, Issue: 12 09/10/2003 
A family portrait of Jupitier and its largest moons. The moons are (from top to bottom) Io, Europa, Ganymede, and Callisto.
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A line diagram of the Galileo spacecraft.
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The launch of the Galileo spacecraft from the cargo bay of the Space Shuttle Atlantis.
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Other Articles in This Issue:
First African-American in Space Celebrates 20th Anniversary of Flight
Farthest, Faintest Solar System Objects Found Beyond Neptune
Chandra X-ray Observatory "Hears" a Supermassive Black Hole in Perseus
Lance Bass Named Youth Spokesperson for World Space Week

Galileo's 8-Year Relationship with Jupiter Ends with a Bang

The flight team for NASA's Jupiter-orbiting Galileo spacecraft ceased operations on February 28, 2003, after a final playback of scientific data from the robotic explorer's tape recorder. At the time, the team had written commands for the onboard computer to manage the spacecraft for its short remaining lifetime. Galileo, after coasting for the seven months, is preparing for a plunge into Jupiter's atmosphere on the 21st of September.

"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, California. "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.

The onboard supply of propellant is nearly depleted. Without propellant, the spacecraft is not be able to point its antenna toward Earth nor adjust its trajectory, so controlling the spacecraft will no longer be possible. Last year the flight team 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 took 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.

A countdown clock along with simulated views of the Galileo spacecraft and its collision course with Jupiter, updated every five minutes, can be found at:

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