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L. Le

Publications and source records attributed to L. Le.

A Multilayered Accretionary Rim on a CAI in the NWA 10758 CV3 Chondrite

Northwest Africa (NWA) 10758 is a Bali type oxidized CV3 chondrite, and section JSC1 contains a large (~2.4×1.4 cm), melilite-rich, type A Ca-Al rich inclusion (CAI), briefly introduced before [1,2]. The exceptional feature of this CAI is a thick (locally >5 mm) fine- to coarse-grained, accretionary rim exhibiting at least 6 distinct layers (Fig. 1). This rim may have formed during passage of the still hot CAI through diverse “clouds” of dust, and thus warrants detailed characterization.

M. Zolensky↗

Preliminary Examination of Returned Samples From Bennu Using Quantitative Particle Analysis in the Scanning Electron Microscope

The sample of regolith collected from asteroid Bennu by NASA’s OSIRIS-REx spacecraft will land in Utah on September 24, 2023. A 100-mg aliquot of fine Bennu dust adhering to the internal surfaces of the sample return capsule and associated hardware will be collected by curation staff during disassembly and analyzed immediately by members of the sample analysis team in a “Quick-Look” (Q-L) procedure. The Q-L objectives are (1) to provide images for release to the public to inform on the nature of the returned sample, and (2) to perform a reconnaissance investigation of the mineralogic characteristics of the returned material for science purposes. We will determine the minerals that occur in the dust, assess their diversity, and determine relative abundances at the >5% level using a combination of optical microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, and field-emission scanning electron microscopy (SEM). Here we describe the procedures and techniques developed for the Q-L analyses using analog samples analyzed by SEM equipped with energy dispersive X-ray spectroscopy (EDX). To test these techniques, we have applied them to several samples, including powders of the Murchison (Fig. 1) and Orgueil meteorites, as well as simulant samples prepared by the mission.

OSIRIS-REx↗

A Rather Thick, Multilayered, Accretionary Rim on A Rather Large CAI in the NWA 10758 CV3 Chondrite

Northwest Africa (NWA) 10758 is a Bali type oxidized CV3, and section JSC1 contains a large (~ 2.4 x 1.4 cm), melilite-rich, type A Ca-Al rich inclusion (CAI), briefly introduced by Ross et al. [1]. The exceptional feature of this CAI is a thick (locally >5mm) fine- to coarse-grained, accretionary rim exhibiting at least 6 distinct layers. As such, this rim may sample a very wide region of the nebula, and mineralogically-diverse “clouds” of dust, and thus warrants detailed characterization.

M. Zolensky↗

Space Weathering in OSIRIS-REx Samples From Bennu: Impact Melt Deposits

Early analyses of regolith samples from asteroid Bennu delivered by the OSIRIS-REx spacecraft showed a mineralogy dominated by hydrated silicates, sulfides, magnetite, phosphates, and abundant organic matter, in addition to other minor/trace phases. A major objective of the sample analysis campaign is to understand the nature and extent of space weathering processes recorded by returned samples from Bennu. Here we report our preliminary transmission electron microscope (TEM) observations of impact melt deposits on surfaces of Bennu sample particles.

L. P. Keller↗