Galileo, the 14 year old spacecraft, designed to study Jupiter and its moons crashed into Jupiter in its final mission. This suicidal crash comes at the end of its 35th orbit of the planet -- far longer than the 11 orbits the spacecraft originally was planned to complete. What makes this crash fascinating is that this crash was intentionally set up to protect Europa- one of Jupiter’s moons.
One of the Galileo missions had discovered the presence of a salty ocean under the ice shield on Europa. Oceans under the icy surfaces could provide habitats where microscopic life might already exist. It is believed that Galileo may be carrying with it, single-celled organisms from home. Some Earth microbes are known to have survived for years in space in a dormant state on Galileo. Should Galileo have been left to its own course, there was a possibility of Galileo impacting Europa. Scientists feared that should this impact occur, microbes from Galileo may contaminate the life forms on Europa. Terrestrial microorganisms could conceivably pose a threat to microbes that may exist on Europa. The extinction of life there would be a major loss.
One of the primary objectives of astrobiologists is to not only safeguard the Earth from extraterrestrial microorganisms, but also prevent Earth microbes from infecting other planets.
Galileo has overcome many difficulties during its 14 year long tenure. It was facing several technical problems, and was expected to crash sooner or later. Scientists are happy that they could design its safe end by crashing it into Jupiter. Thanks to the large size of Jupiter(the largest planet of the solar system), the unmanned 3000 pound spacecraft, traveling at nearly 108,000 mph vaporised without any harm to the planet.