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Recommendation on Orbiting Sample Cleanliness.

Charles S Cockell¹, Rohit Chitale², Brian Clement³

¹University of Edinburgh, Centre for Astrobiology, School of Physics and Astronomy, Edinburgh, UK.

|December 14, 2021

Summary

The Mars Sample Return (MSR) campaign recommends cleaning the Orbiting Sample (OS) container to a Planetary Protection level 4a standard. This ensures sample integrity while balancing feasibility for the MSR mission.

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Area of Science:

Planetary Science
Astrobiology
Space Mission Operations

Background:

The NASA-ESA Mars Sample Return (MSR) campaign aims to bring Martian samples to Earth for analysis.
The Orbiting Sample (OS) container is critical for sample containment during the MSR mission.
Maintaining stringent cleanliness within the OS is paramount for mission success and scientific integrity.

Purpose of the Study:

To evaluate and recommend appropriate planetary protection cleanliness levels for the MSR Orbiting Sample (OS) container.
To assess the trade-offs between COSPAR planetary protection cleanliness levels 4a and 4b for the OS interior.
To provide a consensus recommendation and rationale for the OS cleanliness requirements.

Main Methods:

Convened the Mars Sample Return Orbiting Sample Tiger Team (OSTT) to discuss cleanliness options.
Evaluated Committee on Space Research (COSPAR) planetary protection regulations, specifically levels 4a and 4b.
Documented the team's consensus opinion and the reasoning behind the recommendation.

Main Results:

The OSTT recommended cleaning the OS interior to a Planetary Protection level 4a.
The recommendation includes striving for any feasible additional measures towards level 4b.
Level 4a requires <300 bacterial spores/m² and <3 x 10⁵ bacterial spores on the spacecraft interior.

Conclusions:

The recommended cleanliness level (4a with efforts toward 4b) balances stringent requirements with mission feasibility.
This approach ensures the integrity of returned Martian samples for scientific study.
The decision supports the overarching goals of the Mars Sample Return campaign.