Galileo to plunge into Jupiter this weekend.....

[Drbio]

Last gasp for Galileo mission to Jupiter

Associated Press
PASADENA, Calif. --NASA scientists said they hope to wring a final few hours of work from the doomed Galileo spacecraft before it plunges into Jupiter this weekend.

Galileo will end its 14-year mission by diving into the turbulent atmosphere of the solar system's largest planet around 1 p.m. on Sunday. Friction will vaporize the spacecraft, which will be traveling at nearly 108,000 mph.

In the hours before impact, scientists expect Galileo to transmit the final scientific measurements of its mission.

``We expect to be collecting science data all the way in,'' Claudia Alexander, manager of the $1.5 billion project, said Wednesday.

On tap are observations that may confirm the presence of a ring of chunky material circling Jupiter at the orbit of Amalthea, a bright red, inner moon.

A swoop past the moon that Galileo made in November suggested the presence of such a ring.

However, it is unclear whether NASA will succeed in squeezing final data from Galileo.

On previous close brushes with Jupiter, the planet's intense radiation forced the spacecraft to enter standby mode and await further commands from Earth.

There will be no time for such commands to be sent on Sunday.

``We're keeping our fingers crossed,'' Alexander said.

Even if it blinks out, Galileo will sail into Jupiter on its own, vanishing behind the planet before it enters its atmosphere. It is on target to strike Jupiter just south of its equator, ending a voyage that's covered 2.8 billion miles.

Galileo has orbited Jupiter since 1995, studying the planet and its posse of quirky moons. NASA extended the mission three times.

Galileo is now low on the propellant needed to trim its course and point its antenna toward Earth.

Rather than strand Galileo in orbit, NASA put the 3,000-pound probe on a collision course with Jupiter. The idea is to ensure it never accidentally collides with Europa and contaminates the Jovian moon with stowaway microbes from Earth.

Galileo's observations revealed that Europa probably has a large ocean, which may harbor extraterrestrial life.

``Ironically, Galileo itself has given us the reason'' to destroy it, said Colleen Hartman, director of NASA's solar system exploration division.

NASA has begun designing a follow-on mission to Galileo, expected to launch in the next decade.

[Murphy3]

is she cute?

[Drbio]

Oh my....[img]i/expressions/rolleye.gif[/img]



good one murph.

[Usually Lurkin]

Galileo's observations revealed that Europa probably has a large ocean, which may harbor extraterrestrial life.

if we find no evidence of life, we should crash a ship full of microbes onto that moon. Just to see what happens.

[jacktruth]

I thought he was dead.

[Chiwas]

Many Miles, Many Moons: A Galileo Album
By JOHN NOBLE WILFORD


n Sunday, several hundred engineers and scientists will gather at the Jet Propulsion Laboratory in Pasadena, Calif., and await the end of the Galileo spacecraft in a suicide plunge into Jupiter's dense atmosphere.

They are the kind of professionals who try to resist anthropomorphizing their machines, even one like Galileo, which has been a longtime companion in their lives and careers. But they freely concede that they will be there at the end as an act of homage.

"It will be the equivalent of a wake," said Dr. Claudia Alexander, manager of the project.

Few flight teams have had to contend with a spacecraft more demanding of their attention and ingenuity.

Launched in 1989 after a long delay caused by the loss of the space shuttle Challenger in 1986, Galileo took six years going to Jupiter, almost half a billion miles away, by a circuitous route dictated by the limited power of its initial rocket boost.

From then on, the three-ton spacecraft was tormented by as many afflictions as poor Job.

The main antenna, the one that scientists counted on for the return of pictures and data of Jupiter and its four largest moons, failed to unfurl. Engineers had to rely on a smaller antenna and an improvised system of data shorthand.

Galileo was further hobbled by an erratic tape recorder. After the craft began orbiting Jupiter in 1995, repeated zappings from the planet's intense radiation belts damaged other instruments.

In nearly all cases, engineers managed to reprogram software to overcome or work around the setbacks. As recently as last November, in its last encounter with a Jovian moon, tiny Amalthea, the spacecraft "got hammered again by radiation," Dr. Alexander said.

The spacecraft's fault-detection system came to the rescue once again, turning off nearly all operations and saving the science data from the encounter.

But the tape recorder was left stuck. Flight controllers applied electrical current to the recorder, on and off and on again, repeatedly, until the molecular structure was altered enough to unstick the recorder for transmitting data.

"Miracles continued to happen on this mission," Dr. Alexander said.

Indeed, in spite of everything, scientists rate Galileo as one of the most successful missions of planetary exploration. Galileo's eight-year orbit of Jupiter included several close encounters of each of Jupiter's major satellites, Ganymede, Callisto, Io and Europa. No two were found to be anything alike.

Ganymede is not only the largest moon in the solar system, but it is also larger than Mercury and Pluto. Galileo discovered that Ganymede had a strong magnetic field, "something no one thought a moon would have," said Dr. Rosaly Lopes-Gautier, a member of the project's science team.

Icy Callisto appears to be the most heavily cratered object in the solar system. Io is bubbling with erupting volcanoes, 152 by Dr. Lopes-Gautier's latest count. The phenomenon was discovered on previous flybys by Voyager spacecraft, but Galileo determined how plentiful and persistent the eruptions are. The lava flows are hotter than anything seen on Earth in two billion years.

Europa has given scientists the most reason to celebrate and speculate. In Galileo's eight flybys, the appearance of Europa's frozen crust suggested that it covered an immense ocean. And where there is so much liquid water, could there also be some forms of life?

That discovery sealed Galileo's ultimate fate. If the spacecraft, after running out of maneuvering fuel, should crash into Europa, it might contaminate that moon with stowaway microbes from Earth and confound future searchers for indigenous life. So the decision was made to vaporize the spacecraft by putting it on a collision course with Jupiter.

"The course is unalterable," Dr. Alexander said. "The last fuel was expended several months ago, to make sure we hit the planet."

Tracking data show that the craft, traveling 30 miles a second toward the end, will crash into Jupiter on its night side. At 12:50 p.m., Pacific time, the old Galileo hands in Pasadena, hearing no radio signal, will know that their spacecraft is no more.