arXiv subjects

D. P. Glavin

Publications and source records attributed to D. P. Glavin.

3 recordsLinked to original sources

arXiv2026

Best Bulk Bennu (B3): Elemental compositions of aggregate samples from asteroid Bennu

Ivuna-type (CI) carbonaceous chondrites have long served as proxies for the bulk Solar System composition due to their close agreement with solar photospheric abundances and enrichment in volatile elements relative to other chondrite classes. However, CI chondrites have been subject to terrestrial alteration, which may have modified their original mineralogies and redistributed aqueously mobile elements. NASA's OSIRIS-REx mission delivered pristine material from the carbonaceous asteroid Bennu, and initial analyses revealed close compositional similarities with CI chondrites. This provides a valuable opportunity to refine estimates of the bulk Solar System composition. We report concentrations of 63 elements in aggregate (bulk, unsorted) Bennu material (representing a combined mass of ~8 g) analyzed across four laboratories. Within analytical uncertainties, we find no statistically significant differences among aliquots of two aggregate samples that were homogenized into powders, or among subsamples (including two previously reported) of a non-homogenized aggregate sample. Nor do we find measurable variations among sample masses ranging from tens of milligrams to several grams. These findings indicate that the material returned from Bennu is well mixed at the aggregate scale. Combining all of the data, we derive an average bulk elemental composition that we term Best Bulk Bennu (B3). Comparison of B3 with an average CI chondrite composition shows excellent agreement within analytical uncertainties, confirming that terrestrial alteration of CI chondrites is effectively isochemical for non-highly volatile elements. B3 and the CI chondrite average composition compare similarly to solar photospheric composition. Thus, CI meteorites and returned samples of carbonaceous asteroids are the best available materials for estimating the bulk Solar System composition of non-highly volatile elements.

astro-ph.EP↗

arXiv2022

Airfall on Comet 67P/Churyumov-Gerasimenko

We here study the transfer process of material from one hemisphere to the other (deposition of airfall material) on an active comet nucleus, specifically 67P/Churyumov-Gerasimenko. Our goals are to: 1) quantify the thickness of the airfall debris layers and how it depends on the location of the target area, 2) determine the amount of $\mathrm{H_2O}$ and $\mathrm{CO_2}$ ice that are lost from icy dust assemblages of different sizes during transfer through the coma, and 3) estimate the relative amount of vapor loss in airfall material after deposition in order to understand what locations are expected to be more active than others on the following perihelion approach. We use various numerical simulations, that include orbit dynamics, thermophysics of the nucleus and of individual coma aggregates, coma gas kinetics and hydrodynamics, as well as dust dynamics due to gas drag, to address these questions. We find that the thickness of accumulated airfall material varies substantially with location, and typically is of the order $0.1$-$1\,\mathrm{m}$. The airfall material preserves substantial amounts of water ice even in relatively small (cm-sized) coma aggregates after a rather long ($12\,\mathrm{h}$) residence in the coma. However, $\mathrm{CO_2}$ is lost within a couple of hours even in relatively large (dm-sized) aggregates, and is not expected to be an important component in airfall deposits. We introduce reachability and survivability indices to measure the relative capacity of different regions to simultaneously collect airfall and to preserve its water ice until the next perihelion passage, thereby grading their potential of contributing to comet activity during the next perihelion passage.

astro-ph.EP↗

arXiv2017

OSIRIS-REx Contamination Control Strategy and Implementation

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS- REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm2 of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.

astro-ph.IM↗