National Aeronautics and Space Administration Planetary Protection Office

About the Office


News and Current Events


Mission Categories

Solar System Bodies

List of Missions

Mission Design & Requirements

Methods & Implementation

International Policy

Research in Planetary Protection

History of Planetary Protection

Course in Planetary Protection

Glossary of Terms




About Planetary Protection


The planetary protection procedures applied to a given spacecraft are currently determined by the type of mission (e.g., flyby, orbiter, lander, rover) and the biological interest posed by the spacecraftÂ’s destination. Landers and rovers destined towards objects of high biological interest (e.g., the Mars Exploration Rovers) must undergo careful cleaning. Heat sterilization may be required if a spacecraft carrys a life detection experiment (e.g., the Viking Landers).

Each mission will fall into one of five categories based upon the planetary protection status designated by the Planetary Protection Officer. Each category has different planetary protection requirements as defined by NASA Procedural Requirements 8020.12C: PlanetaryProtection Provisions for Robotic Extraterrestrial Missions, and summarized in the following table:

Not of direct interest for understanding the process of chemical evolution. No protection of such planets is warranted and no requirements are imposed. Any I
Of significant interest relative to the process of chemical evolution but only a remote chance that contamination by spacecraft could jeopardize future exploration. Any II
Of significant interest relative to the processes of chemical evolution and the origin of life, or for which scientific opinion holds that a significant chance of contamination would jeopardize a future biological experiment. Flyby, Orbiter III
  Entry Probe, Lander, Rover IV
Any Solar System Body. Return to Earth V

Stipulations associated with the mission encompass a variety of field and reporting requirements, including the use of bioreduction techniques (which effectively lower the microbial contamination level on the spacecraft at the time of launch), microbial assays (which quantify the level of biological burden on the spacecraft), and reporting requirements (which estimate parameters such as the probability of inadvertent impact of the spacecraft with a solar system body).