Combining IR and X‐ray microtomography data sets: Application to Itokawa particles and to Paris meteorite

Abstract

In the near future, a new generation of sample return missions (Hayabusa2, OSIRIS‐REx, MMX, etc.) will collect samples from small solar system bodies. To maximize the scientific outcome of laboratory studies and minimize the loss of precious extraterrestrial samples, an analytical sequence from less destructive to more destructive techniques needs to be established. In this work, we present a combined X‐ray and IR microtomography applied to five Itokawa particles and one fragment of the primitive carbonaceous chondrite Paris. We show that this analytical approach is able to provide a 3‐D physical and chemical characterization of individual extraterrestrial particles, using the measurement of their 3‐D structure and porosity, and the detection of mineral and organic phases, and their spatial co‐localization in 3‐D. We propose these techniques as an efficient first step in a multitechnique analytical sequence on microscopic samples collected by space missions.

Optical tweezers in a dusty universe

“…Physical and compositional properties of the interplanetary dust complex Most of the compositional properties of the interplanetary dust complex derives from the cosmochemical analyses of samples recovered from: (1) Earth's surface, e.g., micrometeorites collected in Antarctica [80,81,83]; (2) Earth's stratosphere, by balloon born instruments, e.g., DUSTER, designed for nondestructive and uncontaminated collection of solid particles from tens of microns down to 200 nm in size [84] and by stratospheric NASA/aircraft passive sticking on silicon oil-coated plates [85]. A critical contribution is also given by laboratory analyses of samples, i.e., collected, and brought back to Earth, from asteroid surfaces [86] and in a cometary coma [18,19]. In addition, cometary dust were studied in situ from the onset of cometary activity to its cessation after perihelion by the Rosetta/ESA space mission [87][88][89].…”

A preparation sequence for multi‐analysis of µm‐sized extraterrestrial and geological samples

“…The needle was connected to a motor to ensure the rotation of the sample under the microscope, around the needle axis. Using the method described by Dionnet et al (2020), we collected a series of 2-D hyper-spectral maps in transmission for 180 angles, which were later reconstructed to obtain the distribution of the different functional groups in 3-D. The spectral resolution was 16 cm À1 for the 3-D-IR tomography.…”

“…XCT allowed us to study the morphology of the sample at a smaller scale. By combining the two techniques on the same sample, we used the better spatial resolution of the X-ray data to constrain the shape of the IR reconstruction and to partially compensate the scattering/diffraction effects visible on IR data (Dionnet et al 2020). An example of a whole sequence in 3-D, containing both IR tomography and XCT, has been performed on a fragment of NWA 5515 meteorite and will be presented later in the article.…”

“…The organic matter and water were reconstructed using the area of the aliphatic (1335-1425 cm À1 ) and of the OH (1570-1657 cm À1 ) bending modes, respectively. f) Sectional plan showing the location of the slice that is extracted from the 3-D-IR reconstructed sample (see Dionnet et al [2020] for details). g-j) 2-D slices virtually extracted from the 3-D reconstruction of the NWA-5515 grain.…”

“…Special care is taken during sample preparation to minimize sample loss and sample contamination. Infrared computed microtomography (IR-CT) is performed as a first step for a nondestructive characterization of the 3-D structure and chemistry of the grain (Dionnet et al 2020). This notably allows the identification of subregions of interest, which can be targeted for further analyses.…”