Galileo Mission Extended to Further Study of Jupiter"s Moons By Robert Roy Britt Senior Science Writer posted: 02:53 pm ET 15 March 2001 ET
Headline: Galileo Mission Extended to Further Study of Jupiter's Moons
The Galileo spacecraft, like the enduring Renaissance philosopher-mathematician for whom it is named, has repeatedly survived harsh attacks and long bouts of isolation, all the while finding time to make important scientific discoveries.
It has showed us that
Jupiter's moon Europa likely has a vast ocean under its icy surface, a place many scientists would now like to look for life.
On Thursday NASA officials rewarded the craft, which was launched more than a decade ago and has been studying Jupiter and its moons for the last five years, by extending its mission for the third time.
"Workhorse of a spacecraft"
While Galileo Galilei had to tiptoe around the Pope to transmit his then heretical ideas (via a foreign publisher), the spacecraft had little trouble convincing those in charge of its worth. And so data will continue to flow from
"We're proud that this workhorse of a spacecraft has kept performing well enough that we can ask it to keep serving science a little longer," said Jay Bergstralh, acting director of Solar System Exploration at NASA Headquarters.
Galileo is now slated to make five more flybys of various
Jovian moons. On May 25 it will pass 76 miles (123 kilometers) above Callisto, the second largest of Jupiter's 28 known moons. The effects of Callisto's gravity will set up the probe for a swing over both polar regions of the intensely volcanic moon Io in August and October.
Here are the new mission goals, which officials said will cost $9 million to carry out:
Study the extent of volcanism on Io, both in new and previously active sites.
Determine whether Io generates its own weak magnetic field.
Gain a better understanding of a doughnut-shaped ring, called the Io Torus, that encircles Jupiter and contains electrically charged gases.
In November 2002, Galileo will swing closer to Jupiter than ever before, dipping within about 300 miles (500 kilometers) of the moon Amalthea, which is less than one-tenth the size of Io and less than half as far from Jupiter.
Scientists will use Galileo measurements to determine the mass and density of Amalthea. They will also study dust particles
as Galileo flies through Jupiter's gossamer rings, which are similar but less noticeable than the rings of Saturn. The craft will also seek new details of the magnetic forces and the densities of charged particles close to the planet.
Plunge to death
Launched Oct. 18, 1989 aboard the Space Shuttle Atlantis, Galileo has survived radiation exposure more than three times what it was built to take, mission specialists say.
But in the end, the spacecraft will end up as dust, just like its namesake. Its demise in 2003 will involve a plunge into the crushing atmosphere of the giant planet. (The former Galileo died blind after a months-long illness at age 75, his mind still spinning with new ideas he termed "partly different from or contrary to those commonly received.")
Galileo's final orbit will take an elongated loop away from Jupiter. Then in August 2003, the spacecraft will head back for a direct impact and burn up as it plows into Jupiter.
"Galileo has already succeeded beyond expectations, and we have the opportunity to learn still more in coming months," said Eilene Theilig, Galileo project manager at NASA's Jet Propulsion Laboratory in Pasadena, CA. "But it is sad to see the end of the road up ahead."
Accomplishments
Some of Galileo's findings:
Produced strong evidence that
Europa has a melted saltwater ocean under the ice layer on its surface, along with indications that Ganymede and Callisto may also harbor liquid saltwater.
Detailed the extensive volcanic processes on Io, catching plumes erupting, fire fountains in process and lava flows expanding.
Delivered a probe that made the first measurements of Jupiter's atmosphere from within
Made the first close approach to an asteroid and made the first discovery of a satellite orbiting an asteroid
Discovered the first internal magnetic field of a moon, Ganymede's.
Provided the only direct observation of Comet Shoemaker-Levy's impact into Jupiter.
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