Planning Implications Related to Sterilization-Sensitive Science Investigations Associated with Mars Sample Return (MSR)

Michael Velbel (1, 2) , Charles Cockell (3) , Daniel Glavin (4) , Bernard Marty (5) , Aaron Regberg (4) , Alvin Smith (6) , Nicholas Tosca (7) , Meenakshi Wadhwa (8, 6) , Gerhard Kminek (9) , Michael Meyer (10) , David Beaty (6) , Brandi Lee Carrier (6) , Timothy Haltigin (11) , Lindsay Hays (10) , Carl Agee (12) , Henner Busemann (13) , Barbara Cavalazzi (14) , Vinciane Debaille (15) , Monica Grady (16) , Ernst Hauber (17) , Aurore Hutzler (9) , Francis Mccubbin (18) , Lisa Pratt (19) , Caroline Smith (20, 21) , Roger Summons (22) , Timothy Swindle (23) , Kimberly Tait (24) , Arya Udry (25) , Tomohiro Usui (26) , Frances Westall (27) , Maria-Paz Zorzano (28, 29)

1 Michigan State University [East Lansing]
2 Smithsonian Institution
3 Edin. - University of Edinburgh
4 GSFC - NASA Goddard Space Flight Center
5 CRPG - Centre de Recherches Pétrographiques et Géochimiques
6 CALTECH - California Institute of Technology
7 CAM - University of Cambridge [UK]
8 ASU - Arizona State University [Tempe]
9 ESA - Agence Spatiale Européenne = European Space Agency
10 NASA Headquarters
11 CSA - Canadian Space Agency
12 The University of New Mexico [Albuquerque]
13 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
14 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
15 ULB - Université libre de Bruxelles
16 OU - The Open University [Milton Keynes]
17 DLR - German Aerospace Center
18 JSC - NASA Johnson Space Center
19 Indiana University [Bloomington]
20 NHM - The Natural History Museum [London]
21 University of Glasgow
22 MIT - Massachusetts Institute of Technology
23 University of Arizona
24 Royal Ontario Museum
25 WGU Nevada - University of Nevada [Las Vegas]
26 JAXA - Japan Aerospace Exploration Agency [Sagamihara]
27 CBM - Centre de biophysique moléculaire
28 CAB - Centro de Astrobiologia [Madrid]
29 University of Aberdeen

The NASA/ESA Mars Sample Return (MSR) Campaign seeks to establish whether life on Mars existed where and when environmental conditions allowed. Laboratory measurements on the returned samples are useful if what is measured is evidence of phenomena on Mars rather than of the effects of sterilization conditions. This report establishes that there are categories of measurements that can be fruitful despite sample sterilization and other categories that cannot. Sterilization kills living microorganisms and inactivates complex biological structures by breaking chemical bonds. Sterilization has similar effects on chemical bonds in non-biological compounds, including abiotic or pre-biotic reduced carbon compounds, hydrous minerals, and hydrous amorphous solids. We considered the sterilization effects of applying dry heat under two specific temperature-time regimes and the effects of γ-irradiation. Many measurements of volatile-rich materials are sterilization sensitive-they will be compromised by either dehydration or radiolysis upon sterilization. Dry-heat sterilization and γ-irradiation differ somewhat in their effects but affect the same chemical elements. Sterilization-sensitive measurements include the abundances and oxidation-reduction (redox) states of redox-sensitive elements, and isotope abundances and ratios of most of them. All organic molecules, and most minerals and naturally occurring amorphous materials that formed under habitable conditions, contain at least one redox-sensitive element. Thus, sterilization-sensitive evidence about ancient life on Mars and its relationship to its ancient environment will be severely compromised if the samples collected by Mars 2020 rover Perseverance cannot be analyzed in an unsterilized condition. To ensure that sterilization-sensitive measurements can be made even on samples deemed unsafe for unsterilized release from containment, contingency instruments in addition to those required for curation, time-sensitive science, and the Sample Safety Assessment Protocol would need to be added to the Sample Receiving Facility (SRF). Targeted investigations using analogs of MSR Campaign-relevant returned-sample types should be undertaken to fill knowledge gaps about sterilization effects on important scientific measurements, especially if the sterilization regimens eventually chosen are different from those considered in this report.

Domaines: Planète et Univers [physics]

Michael Velbel, Charles Cockell, Daniel Glavin, Bernard Marty, Aaron Regberg, et al.. Planning Implications Related to Sterilization-Sensitive Science Investigations Associated with Mars Sample Return (MSR). Astrobiology, 2021, 22, ⟨10.1089/AST.2021.0113⟩. ⟨hal-03671832⟩