Planetary Protection Implementation and Verification Approach for the Mars 2020 Mission

The Mars 2020 Flight System comprises a Cruise Stage; Aeroshell; Entry, Descent, and Landing system; Perseverance rover; and the Ingenuity helicopter. The Perseverance rover was successfully delivered to Jezero Crater on February 18, 2021. Among its science objectives, Perseverance is meant to search for rocks that are capable of preserving chemical traces of ancient life, if it existed, and to core and cache rock and regolith samples. The Perseverance rover is gathering samples for potential return to Earth as part of a Mars Sample Return campaign. Thus, controlling the presence of Earth-sourced biological contamination is important to protect the integrity of the scientific results as well as to comply with international treaty and NASA requirements governing Planetary Protection prior to launch. An unprecedented campaign of sampling and environmental monitoring occurred, which resulted in over 16,000 biological samples collected throughout spacecraft assembly. Engineering design, microbial reduction measures, monitoring, and process controls enabled the mission to limit the total spore bioburden to 3.73 × 10⁵ spores, which provided 25.4% margin against the required limit. Furthermore, the total spore bioburden of all landed hardware was 3.86 × 10⁴, which provided 87% margin against the required limit. This manuscript outlines the Planetary Protection implementation approach and verification methodologies applied to the Mars 2020 flight system and its surrounding environments.