Proposed protocols for opening sample tubes. Drawings courtesy of Oscar Rendón Pérez. In the radial cut approach, a sharp carbide wheel cuts the tube by slowly rotating and squeezing it around the tube (bottom panel, left). The sample is withdrawn from the tube by tilting it and controlling the rate of descent with a piston. The second approach involves making a second cut to push the sample out. A virtue of this approach is that it allows for a more controlled extraction and minimizes the risk of sample clogging in the tube. Both options 1 and 2 involve the sample slipping out of the tube and risk losing the chemical and structural layers of the sample. The third approach involves making two longitudinal cuts in the side of the tube to expose the entire sample inside the tube. Less likely to disturb the physical integrity of the sample, which remains in place in the tube, but involves cutting the tube lengthwise through a layer of white alumina (which is deposited on the tubes to reduce their heat absorption as they settle in the tube of Mars). surface) possibly using a circular blade (bottom panel, right). The potential for contamination is greater with this third approach, as more tube handling is involved, more tube material is cut, and the setup to remove or cut the alumina coating will be more complicated than the wheel cutter used in Approaches 1. and 2. — astro -ph.IM
Preserving the chemical and structural integrity of samples to be returned from Mars is critical to achieving MSR’s science goals.
Given our knowledge of the nature of the samples recovered at Jezero by Perseverance, at least two options should be tried to open the sample tubes: (1) One or two radial cuts in the end of the tube to remove the sample. (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 is likely to minimize contamination, but risks affecting the physical integrity of weakly consolidated samples.
Strategy 2 will be optimal to preserve the physical integrity of the samples, but it increases the risk of contamination and mishandling of the sample, since more manipulations and additional equipment will be required.
Therefore, a flexible approach to opening sample tubes is required, and several options must be available, depending on the nature of the returned rock samples. Both opening strategies 1 and 2 may need to be available when samples are returned to handle different sample types (for example, loosely bound sediments vs. hardened magmatic rocks).
This question should be revisited after engineering tests are performed on analog samples. MSR sample tubes will have to be opened under strict BSL4 conditions and this aspect must be integrated into the planning.
N. Dauphas, SS Russell, D. Beaty, F. Thiessen, J. Barnes, L. Bonal, J. Bridges, T. Bristow, J. Eiler, L. Ferriere, T. Fornaro, J. Gattacceca, B. Hoffman , EJ Javaux, T. Kleine, HY McSween, M. Prasad, L. Rampe, M. Schmidt, B. Schoene, KL Siebach, J. Stern, N. Tosca
Comments: 8 pages, 3 figures, 1 table, 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)
Shipping history
From: Nicholas Dauphas
[v1] Wednesday, January 11, 2023 20:00:15 UTC (745 KB)
https://arxiv.org/abs/2301.04694
Astrobiology