Planetary Protection at NASA
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Missions That Explore Our Solar System


Illustration of Galileo in orbit around Jupiter
Illustration of Galileo in orbit around Jupiter – NASA/JPL

NASA’s Galileo mission to Jupiter was launched on October 18, 1989, and arrived at Jupiter in December 1995. The spacecraft spent nearly eight years collecting vast amounts of scientific data on the planet and its moons.

The Galileo mission was classified Category II for planetary protection purposes, requiring documentation only reporting probabilities of impact, contamination control procedures used during assembly, and disposition of all launched hardware at completion of the mission. Microbiological assays were not required. Documentation included the Project Galileo Planetary Protection Plan, the Galileo Planetary Protection Pre-Launch Report, the Galileo Planetary Protection Post-Launch Report, and the Galileo Planetary Protection End of Mission Report.

The End of Mission Report included the option of taking steps to ensure that the spacecraft would not inadvertently impact a place of potential interest to astrobiological investigators. Because Galileo collected evidence of water on Europa, Ganymede and Callisto, this end-of-mission option was exercised. On September 21, 2003, mission managers sent Galileo into the atmosphere of Jupiter to burn up at the end of its operating life, thereby preventing inadvertent collision with and possible contamination of one of Jupiter’s icy moons.

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