PASADENA, Calif. -- NASA's aging Galileo spacecraft deliberately plunged into Jupiter's turbulent atmosphere Sunday, bringing a fiery conclusion to a 14-year, $1.5 billion exploration of the solar system's largest planet and its moons.
The unmanned spacecraft, traveling at nearly 108,000 mph, was torn apart and vaporized by the heat and friction of its fall through the clouds after it dove into the atmosphere at 2:57 p.m. EDT as planned.
At NASA's Jet Propulsion Laboratory, hundreds of scientists, engineers and their families counted down the last seconds before the spacecraft ended its 2.8 billion-mile journey from Earth.
"We haven't lost a spacecraft, we've gained a new stepping stone in exploration," said Torrence Johnson, the mission's project scientist.
Rosaly Lopes, another scientist on the mission, called Galileo's descent "a spectacular end to a spectacular mission."
"Personally, I am a little sad. I had the time of my life on Galileo and I'm a little sad to say goodbye to an old friend," Lopes added.
Despite the glitches that plagued Galileo since its 1989 launch aboard the space shuttle Atlantis, it was one of the National Aeronautics and Space Administration's most fruitful missions.
During its thrice-extended mission, Galileo discovered the first moon of an asteroid, witnessed the impact of a comet into Jupiter and provided firm evidence of salty oceans on three of the planet's moons. Scientists consider one of the three, Europa, the most likely place in the solar system to harbor extraterrestrial life.
Among the most stunning of the 14,000 images returned by Galileo were those of the moon Io. Galileo caught some of the moon's more than 150 volcanoes actively spewing lava and plumes of dust and gas.
"It had more surprises, better stuff waiting to be discovered than we ever could have imagined," said Andy Ingersol, a Jupiter scientist at the California Institute of Technology.
The last of Galileo's science measurements arrived on Earth after the spacecraft was destroyed Sunday, taking 43 minutes to cross half a billion miles of space at the speed of light.
"I just can't believe the spacecraft collected data all the way in," said a tearful Claudia Alexander, Galileo's seventh and last project manager.
NASA initially considered leaving Galileo in orbit after it depleted its onboard store of fuel, which was used to trim its course on each of its 35 spins around Jupiter.
Instead, it opted to crash the 3,000-pound Galileo to eliminate the possibility it could smack into the watery moon Europa and contaminate it with any microbes aboard. Were Earth bugs to survive on Europa, they could compromise future attempts to probe the moon for indigenous life, scientists feared.
NASA intends to return to Jupiter in a decade with another unmanned spacecraft called the Jupiter Icy Moons Orbiter.
Galileo is the first planetary spacecraft NASA has intentionally destroyed since it steered the Lunar Prospector into the Earth's moon in 1999.
It is not the first, however, to dive into Jupiter: A probe released by the spacecraft did so in 1995, collecting data about the planet's atmosphere for about an hour before it was destroyed.
The largest challenge of the Galileo mission was the loss of the use of the spacecraft's umbrella-like main antenna, which failed to unfurl two years after its 1989 launch. That forced NASA to rely on a smaller antenna, which severely squeezed the amount of data Galileo returned to Earth.
The intense radiation close to Jupiter also took its toll on the electronics of the spacecraft, itself powered by radioactive plutonium.
The spacecraft was named for Galileo Galilei, the Italian astronomer who discovered Jupiter's four largest moons in 1610 and whose understanding of the mechanics of the solar system sometimes ran afoul of Vatican orthodoxy.
"Remember, he wanted the truth, whatever it was," said Jim Erickson, a former Galileo project manager. "And we provided it."
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