Mars 2020 Mission Biological Return Sample Contamination Control Approach and Verification.

Area of Science:

• Planetary Science
• Astrobiology
• Microbiology

Background:

• The Mars 2020 Perseverance rover utilizes a Sample Caching System (SCS) for collecting and caching Martian samples.
• Strict mission requirements mandate minimal Earth-sourced viable organisms (VOs) in returned samples for scientific integrity.

Purpose of the Study:

• To detail bioburden mitigation and reduction strategies for the SCS hardware.
• To describe the aseptic assembly process for the SCS.
• To report the estimated viable organisms (VO) for returned Martian samples.

Main Methods:

• Implementation of specialized bioburden mitigation and reduction approaches for SCS hardware.
• Aseptic assembly procedures for the Sample Caching System.
• Calculation and estimation of viable organism (VO) levels in encapsulated samples.

Main Results:

• The implemented methods significantly reduced microbiological contamination.
• Conservative estimates show the probability of a single VO is over an order of magnitude below the mission requirement.
• Best estimates indicate the probability of a single VO exceeds two orders of magnitude below the requirement.

Conclusions:

• The SCS bioburden mitigation strategies successfully meet stringent planetary protection requirements.
• Martian samples collected by Perseverance are highly likely to be free of Earth-sourced viable organisms.
• The implemented protocols ensure the integrity of samples for future Earth-based scientific investigations.