High Quality Content by WIKIPEDIA articles! Planetary protection is a guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth. A major goal of planetary protection is to preserve the planetary record of natural processes by preventing human-caused microbial introductions, also called forward contamination. Planetary protection reflects both concerns associated with the unknown nature of the space environment and the desire of the world scientific community to preserve the pristine nature of celestial objects until such time as they could be studied in an effective manner. The need for planetary protection measures is strongest for missions designed to return a sample from another planet or celestial body to the Earth (back-contamination).