Mars

Science Priorities For The Extraction Of The Solid MSR Samples From Their Sample Tubes

By Keith Cowing
Press Release
astro-ph.IM
January 12, 2023
Filed under , , , , , ,
Science Priorities For The Extraction Of The Solid MSR Samples From Their Sample Tubes
Proposed protocols for opening the sample tubes. Drawings courtesy of Oscar Rendon Perez. In the one radial cut approach, a sharp hard metal wheel shears through the tube by slowly rotating and tightening it around the tube (bottom panel; left). The sample is extracted from the tube by inclining it and controlling the rate of descent with a piston. The second approach involves doing a second cut to push the sample outwards. A virtue of this approach is that it allows for a more controlled extraction, and it minimizes the risk of the sample getting jammed in the tube. Both options 1 and 2 involve the sample sliding out of the tube and incur the risk of losing the chemical and structural layering of the sample. The third approach involves doing two longitudinal cuts on the side of the tube to expose the whole sample within the tube. It is least likely to disturb the physical integrity of the sample, which stays in place in the tube, but it involves cutting the tube along its length through a white alumina coating (deposited on the tubes to reduce their heat absorption while seating on Mars’ surface) possibly using a circular blade (bottom panel; right). The chance of contamination is higher with this third approach as more tube manipulations are involved, more tube material is cut, and the setup to remove or cut the alumina coating will be more involved than the wheel cutter used in approaches 1 and 2. — astro-ph.IM

Preservation of the chemical and structural integrity of samples that will be brought back from Mars is paramount to achieving the scientific objectives of MSR.

Given our knowledge of the nature of the samples retrieved at Jezero by Perseverance, at least two options need to be tested for opening the sample tubes: (1) One or two radial cuts at the end of the tube to slide the sample out. (2) Two radial cuts at the ends of the tube and two longitudinal cuts to lift the upper half of the tube and access the sample.

Strategy 1 will likely minimize contamination but incurs the risk of affecting the physical integrity of weakly consolidated samples.

Strategy 2 will be optimal for preserving the physical integrity of the samples but increases the risk of contamination and mishandling of the sample as more manipulations and additional equipment will be needed.

A flexible approach to opening the sample tubes is therefore required, and several options need to be available, depending on the nature of the rock samples returned. Both opening strategies 1 and 2 may need to be available when the samples are returned to handle different sample types (e.g., loosely bound sediments vs. indurated magmatic rocks).

This question should be revisited after engineering tests are performed on analogue samples. The MSR sample tubes will have to be opened under stringent BSL4 conditions and this aspect needs to be integrated into the planning.

N. Dauphas, S.S. Russell, D. Beaty, F. Thiessen, J. Barnes, L. Bonal, J. Bridges, T. Bristow, J. Eiler, L. Ferriere, T. Fornaro, J. Gattacceca, B. Hoffman, E.J. Javaux, T. Kleine, H.Y. McSween, M. Prasad, L. Rampe, M. Schmidt, B. Schoene, K.L. Siebach, J. Stern, N. Tosca

Comments: 8 pages, 3 figures, 1 table, report NASA-ESA Mars Rock Team Report
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
Cite as: arXiv:2301.04694 [astro-ph.IM] (or arXiv:2301.04694v1 [astro-ph.IM] for this version)
Submission history
From: Nicolas Dauphas
[v1] Wed, 11 Jan 2023 20:00:15 UTC (745 KB)
https://arxiv.org/abs/2301.04694
Astrobiology

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