A Summary of MEPAG’s Recent Thinking Re: MSR Science

A Summary of MEPAG’s Recent Thinking Re: MSR Science David Beaty April 4, 2010 Presentation to the Planetary Protection Subcommittee Pre-decisional: For discussion purposes only

Introduction • What is MEPAG?: Mars science community forum • How does MEPAG operate?: Science Analysis Groups (SAGs) carry out analyses requested by MEP (and also ESA). Participatory townhalls allow wide participation in program planning. • MEPAG has thought a lot about returned samples: where to acquire them, their nature, and their handling, encapsulation, and quarantine/curation • 2008 ND-SAG (Next Decade) • 2009 MRR-SAG (Mid-Range Rover) • 2010 2R-iSAG (2 Rover) • 2011 E2E-iSAG (End-to-end MSR campaign) Pre-decisional draft for discussion purposes only: Subject to Revision

MEPAG’s Recent Thinking re: MSR 2008: ND-SAG Pre-decisional draft for discussion purposes only: Subject to Revision

Summary of the ND-SAG analysis • Define possible scientific objectives for MSR. • Based on analysis of the MEPAG Goals Document. • What kinds of samples are needed to achieve these objectives? • What are the attributes of the sample collection that will maximize its scientific value? • Number of samples • Mass/sample • Many other factors Pre-decisional draft for discussion purposes only: Subject to Revision

Scientific Objectives for MSR • 11 candidate objectives identified. • KEY OBSERVATION: • No single site on Mars will support all of these • Every site on Mars will support some • => dependency between objectives and landing site Pre-decisional draft for discussion purposes only: Subject to Revision

MSR: What Kinds of Samples? By far the most important, given the proposed objectives. Multiple diverse samples essential. Irvine ROCK Spirit, 01-12-06; sol 721 At least one relatively large sample, preferably also additional smaller samples. REGOLITH/ DUST ATMOSPHERIC GAS One good sample. Pre-decisional draft for discussion purposes only: Subject to Revision

The Concept of Sample Suites • ND-SAG FINDING. MSR will have its greatest value if the samples are organized into suites of samples that represent the diversity of the products of various planetary processes. • Similarities and differences between samples in a suite can be as important as the absolute characterization of a single sample • The minimum number for a suite of samples is thought to be 5-8 samples. • Examples: Sampling several rock layers in a stratigraphic sequence, sampling along a hydrothermal alteration gradient, sampling both “ordinary” regolith and local variations (e.g., salts?) in an area. ND-SAG FINDING. The collection of suites of rocks requires mobility, the capability to assess the range of variation, and the ability to select samples that span the variation. Pre-decisional draft for discussion purposes only: Subject to Revision

Rock Sample Suites: Sedimentary The geochemical variation with stratigraphic position has been interpreted as a diagenetic redistribution of salts and is central to the water question. This could not have been done with 1-2 samples. Burns Cliff Endurance Crater, July 19, 2004 (Opportunity Sol 173) top bottom Clark et al., 2005 (EPSL) Pre-decisional draft for discussion purposes only: Subject to Revision

Sample Size: Rock Samples Example: meteorite QUE-94201 (mass = 12.02 g) QUE-94201 Image courtesy Kevin Righter QUE has been subdivided into over 60 individual samples of some kind or another. EXAMPLE: Utilization of a 1 g chip of this meteorite to make 5 thin sections allowed a great diversity of scientific problems to be addressed by 14 investigators. Pre-decisional draft for discussion purposes only: Subject to Revision

Draft Sample Size: Rock Samples *Life Detection/Biohazard testing Pre-decisional draft for discussion purposes only: Subject to Revision

Sample Packaging & Labeling • There are several fundamental issues: • ND-SAG & MRR-SAG: For the purpose of the major astrobiology/geology-related questions, samples with water and/or volatile organics must have airtight encapsulation (possibly 2/3 of samples by number). • Organics samples require airtight encapsulation to maintain bulk composition (draft: adequate to contain methane) • Samples containing hydrated minerals (especially sedimentary and hydrothermal suite) require airtight encapsulation to retain their components and to protect other samples from alteration by volatile release. • If there are multiple regolith or dust samples (which is desired), they must be packaged to avoid commingling. • Samples must be uniquely identifiable after they are returned to Earth so that the field relationships can be included in the interpretation. Pre-decisional draft for discussion purposes only: Subject to Revision

Sample Packaging & Labeling UNACCEPTABLE Samples mixed Rock sample pulverized ACCEPTABLE UNACCEPTABLE Rock fractured Impact test, June 8, 2000 (max. dynamic load ~ 3400 g, avg. ~2290 g). 10 samples of basalt and chalk in separate sample cache tubes with tight-fitting Teflon caps. Many of the teflon caps came off as a result of the impact. Pre-decisional draft for discussion purposes only: Subject to Revision

Draft Composition of the Collection NOTE: Consensus not yet reached Pre-decisional draft for discussion purposes only: Subject to Revision

MEPAG’s Recent Thinking re: MSR 2008: ND-SAG 2009: MRR-SAG Pre-decisional draft for discussion purposes only: Subject to Revision

Findings Related to Potential Sample Return MEASUREMENTS NEEDED FOR SAMPLE SELECTION: REVISIT VS. NEW SITE FINDING: The capabilities needed to do scientific sample selection, acquisition, and documentation for potential return to Earth would be the same whether the rover would be sent to an area that has been previously visited, or to a new unexplored site. From MRR-SAG: Reducing payload would limit the ability to select or document samples during collection and greatly increase science risk.

Findings Related to Potential Sample Return LANDING SITES FINDING: There are many candidate sites of high potential interest for a future sample return beyond those previously visited or to be visited by MSL. • In addition, using MSR prioritization criteria, additional sites of high potential priority have been recognized • NRC: Astrobiology Strategy for Mars: Several additional kinds of sites of high interest to astrobiology for a potential future return of samples were noted by the NRC (2007). • Community-generated. At recent Mars-related conferences (LPSC, EPSC, AGU, EGU, AbSciCon, GSA, etc.), the global Mars science community has presented many additional sites and site-related astrobiology hypotheses.

Findings Related to Potential Sample Return LANDING SITES FINDING: The best way to evaluate the multiple candidate sites from which to consider returning samples is via an open landing site selection competition with sample return selection criteria. A mission such as the proposed MAX-C presents the first opportunity to evaluate new high-potential sites via such a competition.

Findings Related to Potential Sample ReturnRELATIONSHIP BETWEEN IN SITU SCIENCE AND SAMPLE RETURN The kinds of rocks that would need to be interrogated to achieve the proposed in situ objectives are a class of samples that would also be of crucial interest for potential sample return. Therefore: MAJOR FINDING: The instruments needed to achieve the proposed in situ objectives are the same instruments needed to select samples for potential return to Earth, and to document their context. Because of these compelling commonalities, it makes sense to merge these two purposes into one mission.

MEPAG’s recent thinking re: MSR 2008: ND-SAG 2009: MRR-SAG 2010: 2R-iSAG Pre-decisional draft for discussion purposes only: Subject to Revision

2RiSAG-Proposed PRIMARY SCIENTIFIC OBJECTIVES, 2018 DUAL-ROVER MISSION • Overall Scientific Objectives • At a site interpreted to contain evidence of past environments with high (past) habitability potential, and with high preservation potential for (past) physical and chemical biosignatures, • Evaluate paleoenvironmental conditions; • Assess the potential for preservation of biotic and/or prebiotic signatures; • Search for possible evidence of past life and prebiotic chemistry • Collect, document, and package in a suitable manner a set of samples sufficient to achieve the proposed scientific objectives of a potential future sample return mission. • Independent Scientific Objectives • ExoMars Rover • Characterize the stratigraphy of ancient rocks and the aqueous/geochemical environment as a function of depth in the shallow subsurface (up to 2 m depth). • Search for possible signs of present life • MAX-C Rover • Characterize exposed sequences of geological units across a lateral extent of several km, documenting geological and geochemical variation at scales from 10^3 down to 10^-5 m.

MEPAG’s recent thinking re: MSR 2008: ND-SAG 2009: MRR-SAG 2010: 2R-iSAG 2011: E2E-iSAG Pre-decisional draft for discussion purposes only: Subject to Revision

E2E-iSAG Charter • Consolidate and prioritize a reference set of MSR Campaign Science Objectives. • Use to derive the science-related requirements for the individual flight missions, so that trades between them could be worked. • Derived criteria: • Samples (rock, subsurface, regolith, gas) • Instrumentation • Landing site criteria (threshold and qualifying). Do any acceptable sites exist? • Reference Landing sites • Inputs to Technology Planning Team formation happening now Pre-decisional draft for discussion purposes only: Subject to Revision

Summary • Top 6 things that would affect the ultimate scientific value of MSR: Pre-decisional draft for discussion purposes only: Subject to Revision

A Summary of MEPAG’s Recent Thinking Re: MSR Science