Galileo's journey ends

National Aeronautic and Space Administration

NASA's Galileo spacecraft disintegrated in the atmosphere over Jupiter Sept. 21, ending a journey that spanned 14 years and almost 3 billion miles.

The space agency purposely put the spacecraft on a collision course with Jupiter to avoid an unwanted impact with the planet's moon Europa. Galileo's onboard propellant was nearly depleted, making control of the spacecraft impossible.

NASA officials wanted to avoid contact with Europa after the spacecraft discovered the moon might contain a subsurface ocean, enhancing the possibility of extraterrestrial life.

Launched in 1989 from the Space Shuttle Atlantis, Galileo reached Jupiter six years later. During the next two years, Galileo completed 34 orbits around Jupiter, the solar system's largest planet.

Aside from compiling data on Jupiter's atmosphere, Galileo detailed many characteristics about the planet, including thunderstorms that contain lightning strikes 1,000 times more powerful than those on Earth. Galileo also studied Jupiter's Great Red Spot, a cyclone as big across as Earth's diameter.

Among its many discoveries, Galileo found evidence of subsurface liquid layers of saltwater on the moons of Europa, Ganymede and Callisto. Galileo also studied the volcanic activity on the moon Io.

In 1995, the probe was sent into Jupiter's atmosphere, marking the first-ever readings taken from inside the atmosphere of any of the four giant outer planets.

"It has been a fabulous mission for planetary science, and it is hard to see it come to an end," said Claudia Alexander, Galileo project manager at NASA's Jet Propulsion Laboratory in California. "After traversing almost three billion miles and being our watchful eyes and ears around Jupiter, we're keeping our fingers crossed that, even in its final hour, Galileo will still give us new information about Jupiter's environment."

NASA officials were unsure how much information Galileo would transmit during its fatal plunge. The craft had to pass through an especially high radiation zone during descent.

At the time of its impact, the craft was traveling at a speed of nearly 108,000 miles per hour — the equivalent of traveling from Los Angeles to New York City in 82 seconds, NASA said.