Launched from the cargo bay of Space Shuttle Atlantis in 1989, Galileo showed no signs then of becoming the enduring workhorse it was. The mission was fraught with setbacks, cutbacks, and malfunctions. Budgetary cuts resulted in the loss of the originally specified three-stage booster rocket, meaning a three year, direct approach flight plan had to be recalculated as a six year path helped along by gravity assist "slingshot" maneuvers around other planets. The altered flight plan meant Galileo would be exposed to far higher temperatures than it was originally designed for, so engineers had to devise a series of sunshades to help keep it cooler. It also meant that Galileo's crucial high-gain antenna, which was designed to transmit the bulk of the data back to Earth, had to be kept furled until the craft was far enough from the Sun to prevent heat damage. Unfortunately, when the time came, the antenna simply refused to open. It had gotten stuck in transit, and would not budge. Mission Control was forced to rely on the much weaker low-gain antennae and had to spend three years developing extensive new software and upgrading ground stations.

It wasn't all bad news, though. The altered flight plan took Galileo around Venus, giving scientists their first look at the planet's mid-level clouds and confirming the presence of lightning. It also allowed for numerous Earth observations and extensive mapping of our Moon's surface, including observations of the northern polar regions.

Further along its route to Jupiter, Galileo became the first spacecraft ever to encounter an asteroid when it passed Gaspra on October 29, 1991. Flying within a mere 1,000 miles of the stony asteroid, Galileo beamed back amazingly detailed pictures of its cratered, dust-covered surface.

It met up with another asteroid not quite two years later, when it encountered asteroid Ida on August 28, 1993. Data obtained through Galileo indicated that both Ida and Gaspra have magnetic fields, much like planets. It also showed that Ida, the older of the two asteroids encountered, boasts a satellite of its own, a tiny (less than a mile in diameter) moon called Dactyl. Ida is the first asteroid known to have a natural satellite.

As Galileo was approaching Jupiter in 1994, it was in position to observe a unique and exciting event. The Comet Shoemaker-Levy 9, discovered the year before, was breaking up as it orbited Jupiter, and was projected to dive into the giant planet's atmosphere in July of that year. Galileo had a direct view of the expected impact zone on Jupiter's far side, giving scientists and astronomers their only window into this rare event. Mission control team members were able to program the spacecraft's instruments to collect the data, and obtained some spectacular images of the impacts.

Finally, in December of 1995, Galileo reached its target and entered into orbit around Jupiter. At last, its primary 23-month mission observing Jupiter and its many satellites could begin. During its 11 orbit tour of Jovian space, Galileo had 10 close encounters with Jupiter's major moons, called the Galilean Moons after the great Italian scientist, Galileo Galilei, who first observed them in 1610. The primary mission was declared complete in December of 1997.

But that wasn't nearly the end for the Little Spacecraft That Could. NASA extended Galileo's mission a total of three times, so that they could continue to gain valuable scientific knowledge from Galileo's unique observation post. All in all, Galileo orbited Jupiter 32 times and logged 35 encounters with the major moons, giving scientists an unprecedented look at their characteristics and features. Thanks to Galileo, we now believe there may be liquid oceans under the oddly cracked and striated surface ice of Europa. We know that Io has extensive volcanic activity, perhaps 100 times greater than that currently found on Earth and reminiscent of Earth's early history. We know that Ganymede, the largest moon in our solar system, has its own magnetic field, the first satellite ever found to possess one. And we know that Europa, Ganymede, and Callisto all show evidence of a thin atmospheric layer. These are exciting and important clues in the search of extraterrestrial life, and all were made possible by Galileo's extended life.

In the end, it was the compelling possibility of life on Europa that dictated Galileo's fate. The Little Spacecraft That Could was finally running out of steam, its onboard propellant nearly depleted. Without propellant, Galileo would no longer be able to keep its antenna pointed toward Earth, so ground crews would have no control over its path or trajectory. To prevent any possibility of an impact with the promising Europa, a decision was made to set the craft on a deliberate collision course with Jupiter while such adjustments were still possible.

And so, after a journey of 2.8 billion miles, Galileo went to its long rest, as hundreds current and former Galileo project members and their families gathered in a farewell celebration. It passed by the tiny inner moon Amalthea, performing one last service by taking some specialized readings with its star scanner to help determine whether another, previously unknown ring exists in that area. Then it faded into the great planet's shadow, sent home its final transmission, and slipped out of sight around Jupiter's back side.

Farewell, Galileo. You have served us well.

Click on the links to see some of the remarkable images captured by Galileo:  The Great Red Spot ♦ Calisto ♦ Europa ♦ Ganymede ♦ Io