Illustration of Galileo at Jupiter

Packed like an interplanetary paratrooper, the atmospheric probe aboard NASA's Galileo mission successfully sprang loose from the main spacecraft late tonight and began its long, five-month free-fall toward Jupiter.

"We're delighted to have successfully released the probe on its Jupiter atmospheric mission after having carried it for almost six years," said Galileo Project Manager William O'Neil at NASA's Jet Propulsion Laboratory.

Data from Galileo received at JPL shortly after 11:07 p.m. Pacific Daylight Time confirmed that the probe release went as planned. "The probe is configured for its encounter with Jupiter and is on its way," said Marcie Smith, manager of the probe mission at NASA's Ames Research Center in Moffett Field, CA. "We're very excited to have the probe mission under way."

The probe's flight across the remaining 82 million kilometers (51 million miles) to Jupiter will end abruptly on December 7 when it slams into the giant gas planet's atmosphere. After hitting the top of Jupiter's atmosphere at the highest impact speed ever achieved by a human-made object -- 170,600 kilometers per hour (106,000 miles per hour) -- the rugged probe will unfurl its main parachute and float downward. Seven onboard instruments will directly measure for the first time Jupiter's chemical makeup, winds, clouds and lightning. The probe will radio its data to the Galileo spacecraft for up to 75 minutes.

The probe mission is likely to end when the main Galileo spacecraft passes beyond radio contact with the probe as the spacecraft enters Jupiter orbit. The ultimate fate of the probe may be determined by its battery lifetime, or it may first succumb to the immense pressure of Jupiter's atmosphere and be crushed. Galileo, meanwhile, will begin two years of close-up studies of Jupiter, its moons, rings and powerful magnetic environment.

On July 27, Galileo will fire its main engine to deflects its own course toward an orbit high above Jupiter's cloud tops.

The overall Galileo mission is managed by JPL for NASA's Office of Space Science, Washington, D.C. Galileo's atmospheric probe is managed by NASA's Ames Research Center.

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