Planetary Protection

NASA has designated the Mars 2020 mission as Planetary Protection Category V: Restricted Earth Return. This designation is due to the presence of hardware intended for return to Earth (See Mars 2020 Objective C). Outbound requirements are equivalent to those of Category IVb implemented at subsystem level.

Mars 2020: Restrictions on Landing in a Special Region

The Mars 2020 Science Definition Team (SDT) report concluded that the primary mission objective of exploring an ancient environment does not require the mission to access Special Regions (see Section 8.4).

A Special Region is defined as a location where the temperature could exceed -28° Celsius (-18.4° Fahrenheit) and water activity is at least 0.5. Water is key to life as we know it, and water activity considers the availability of water and water vapor as a potential support for life processes.

The Mars 2020 mission is restricted from landing in, entering, or creating, a Special Region on Mars. The Mars 2020 mission relies on engineering systems that are based on NASA’s Mars Science Laboratory mission, and these engineering systems do not readily support sterilization requirements that apply to missions accessing Special Regions.

Mars 2020: Restrictions on Landing Related to the Presence of Water

The Mars 2020 mission carries a radioisotope thermoelectric generator, which naturally produces heat. The heat produced could raise temperatures, melt ice, and provide an environment where microbial life could reproduce. Thus, the Mars 2020 mission is also restricted from landing in sites where scientists suspect water, brine, or water ice could be present, or could be induced, within 5 meters (about 16.4 feet) of the surface. In the event of an unsuccessful landing, engineers estimate that an impacting spacecraft would not go below a 5-meter depth.

See also: A New Analysis of Mars ‘‘Special Regions’’


Landing Site Workshop: John Grant (, Matthew Golombek (