The Galileo Mission: Hard-Won But Successful

— How about this for a fitting end to a science fiction movie? Our exhausted hero, having fought nearly impossible odds and won every time, is now so old that his memory is shot and his energy is gone, but he still poses some danger to the distant reaches of the solar system.

To remove that one last threat, in the dark of night, we'll vaporize him.

That's the fate that now awaits Galileo, a spacecraft that has risen from its own ashes more times in the last couple of decades than a cat has lives. But that won't happen this time. Several months ago the robotic curmudgeon expended its last bit of energy to set itself on a collision course with Jupiter.

So scientists and engineers at NASA's Jet Propulsion Laboratory in Southern California can now only do what they've learned to do so well in the past. They must wait. Nothing else needs to be done.

And finally, shortly after midnight Sunday, Galileo will plunge into the thick atmosphere of Jupiter at 30 miles per second, ripping itself to shreds before its last pieces of metal are vaporized, ending one of the truly remarkable adventures in the nascent history of space exploration.

Back to Where It Belongs

That's as it should be. It took Galileo so long to get there that Jupiter is where it should remain, along with whatever earthly microbes it carried into space. NASA decided to destroy the spacecraft rather than risk having any of those tiny critters wind up on Europa and thus taint any results from a planned search for life on that Jovian moon.

Many scientists believe the fractured fields of ice on Europa's surface cover a liquid ocean, thus offering us our best chance of finding some form of life elsewhere in the solar system.

Several hundred persons are expected to be on hand at JPL to witness the demise of their charge. They won't see anything, of course. The only proof that the epic mission to Jupiter is over will be silence, the weak radio aboard the spacecraft will have finally died.

But as is so often the case, not everybody who has played a key role in this story will be on hand to witness its conclusion. By the time Galileo reached Jupiter in 1995, four of the lead scientists and engineers at JPL, who had nurtured the spacecraft through political minefields and across technological chasms, had died. Others have died since, including a couple of dozen who were involved in the project through other institutions.

The mission took so long because at times fate seemed set against it.

Winging It

After many delays in launching the spacecraft, it was finally set to go in the mid-1980s when the Challenger exploded. In the aftermath of that tragedy, new regulations prohibited the use of the upper stage rockets that were to have carried Galileo from the space shuttle to Jupiter.

That left the folks at JPL with seemingly no way to launch Galileo, and it seemed for awhile that the mission was dead. Then they came up with a bold scheme. Galileo was launched from the shuttle in 1989, but in the wrong direction. Instead of heading out toward the outer planets, Galileo was headed for the sun.

It then used the gravity of Venus to slingshot itself back toward the Earth, and then on toward Jupiter.

The trip took six years, and just about everything that could go wrong, did go wrong. The main antenna that was supposed to send valuable data back to Earth refused to open, the tape recorder that was to preserve the data jammed, and the craft got zapped so many times by the radiation belt around Jupiter that some of its instruments were nearly fried.

But the wizards at NASA figured out how to deal with those setbacks, and scientists got nearly everything they had hoped for, plus a lot more. On the way to Jupiter Galileo passed by two asteroids, the first spacecraft to do so, and it explored not only Jupiter but its show-stealing moons as well.

There was Europa, with at least some of the conditions that are believed to be necessary for life, and Io, so volcanically active that one area the size of New Jersey had been completely resurfaced in the 17 years since another spacecraft, Voyager, had passed that way.

There have been so many discoveries in the six years that Galileo has been touring the Jovian system that textbooks have had to be rewritten. But in the end, it was Europa that did Galileo in.

Sacrificed for a Microbe

NASA seems a bit obsessed with the idea of finding life somewhere, even if it's just a few tiny microbes. In fact, one microbe would do nicely.

That would prove that life has originated on a body other than Earth, and thus might abound throughout the universe.

That's a tall order for a single microbe. It just wouldn't do to get to Europa in the years ahead and indeed find microbes, but microbes that came from Earth as stowaways aboard Galileo.

So bon voyage Galileo. And thanks for the trip.

Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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