Planetary Protection requirements for each mission and target body are determined based on the scientific advice of the SpaceStudies Board and on NASA or international policy guidelines. Each mission iscategorized according to the type of encounter it will have (e.g., flyby, orbiter or lander)and the nature of its destination (e.g., a planet, moon, comet or asteroid). If the target bodyhas the potential to provide clues about life or prebiotic chemical evolution, a spacecraft goingthere must meet a higher level of cleanliness and some operating restrictions will be imposed.Spacecraft going to target bodies with the potential to support Earth life must undergo stringentcleaning and sterilization processes and greater operating restrictions.