Two unmanned space probes were launched by the United States on This Day in History. One was a great success, while the other was not.
Ranger 5 was the fifth in a series of unmanned probes from the early to mid 1960s designed to travel to the moon. The mission for Ranger 5 was to take pictures of the moon all the way up to a planned impact with the lunar surface. It launched aboard an Atlas-Agena rocket on October 18th, 1962. However, an unexplained malfunctioned caused Ranger 5 to lose power. It did fly by the moon and return a small about of data before going silent. It did not hit the moon or return pictures. It would not be until Ranger 7 (and later Ranger 8 and Ranger 9) that the mission of photos and impact would be successful.
The Galileo spacecraft was launched about the Space Shuttle Atlantis on October 18th, 1989. Whereas other spacecraft such as Pioneer 10 and 11 and Voyager 1 and 2 had merely flown by Jupiter, Galileo was to orbit the solar system’s largest planet. It arrived six years later in 1995 and would orbit the planet for many years. It took thousands of pictures of not only Jupiter, but many of the Jovian moons. It also returned much more data of different kinds, before being deactivated in 2003.