The antenna resembled the ribs of an umbrella, and engineers believe that three of the ribs stuck together instead of popping open. Next, when the spacecraft ’s main (high-gain) antenna was commanded to open in 1991, it failed. Mission planners came up with a clever solution: instead of going straight to Jupiter, Galileo circled the inner solar system several times, first flying by Venus (February, 1990), then Earth (December, 1990), then Earth again (December, 1992), picking up enough velocity from these encounters to begin the real trip to Jupiter. Yet a smaller rocket could not send Galileo directly to Jupiter. However, after the explosion of the space shuttle Challenger during takeoff on January 28, 1986, NASA said that the original rocket (with its large load of explosive fuel) would not be allowed to go up in the shuttle. For example, the probe was originally intended for launch from Earth orbit using a stronger rocket than was eventually used. The Galileo project, which commenced in 1977, was a scientific success despite technical setbacks and political controversy. The atmosphere probe was also mounted on the despun part. These included the main camera (for imaging Jupiter and its moons) and several spectrometers. On the smaller, despun part of the craft were mounted devices that had to be held steady while acquiring data. Antennas for communication with Earth were also mounted on the spun portion, facing backward along the main axis of the spacecraft. The larger, spun portion of the spacecraft contained six scientific instruments that could benefit by constantly scanning different parts of the heavens, including devices that imaged the stars and measured electromagnetic fields and charged-particle flows in space. A spinning section was included was to stabilize the spacecraft, which otherwise would have tumbled randomly as it flew through space or else consumed excessive fuel stabilizing itself with rockets. The orbiter was a dual-spin design, meaning that it was divided into two sections, one that spun at three revolutions per minute and another that did not spin. Together they stood some 21 ft (7 m) high. The Galileo probe was really two spacecraft, an orbiter and an atmospheric descent probe, which were joined until they neared Jupiter. Studying them was a primary objective of the Galileo project. These four moons of Jupiter, its largest, are called the Galilean satellites in The Galileo spacecraft was named after the Italian astronomer Galileo Galilei (1564 –1642), who first discovered the four large moons of Jupiter -Io, Europa, Ganymede, Callisto -in 1610. Galileo greatly enlarged our knowledge of Jupiter and its complex moons. It orbited Jupiter and observed the planet and its moons until it was deliberately crashed into Jupiter ’s atmosphere on September 21, 2003. The probe was launched on Octoand arrived at Jupiter on Decemafter an elaborate, looping journey through the solar system to conserve fuel. The Galileo spacecraft was a robotic probe sent to Jupiter, the largest planet in the solar system, by the United States National Aeronautics and Space Administration (NASA).
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