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

K. Wang; K. Lodders; P. Koefoed; M. Broussard; J. Wimpenny; J. Render; Q. R. Shollenberger; T. S. Kruijer; G. A. Brennecka; M. Amini; V. Lai; D. Weis; K. C. Welten; K. Nishiizumi; D. P. Glavin; J. P. Dworkin; C. M. O'D. Alexander; J. -A. Barrat; P. Haenecour; J. J. Barnes; A. N. Nguyen; H. C. Connolly Jr.; D. S. Lauretta

arXiv · 2610.31828

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

View original source ↗Read source document ↗Export metadata ↓

Abstract

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.

Explore related subjects

astro-ph.EP

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

K. Wang, K. Lodders, P. Koefoed, M. Broussard, J. Wimpenny, J. Render, Q. R. Shollenberger, T. S. Kruijer, G. A. Brennecka, M. Amini, V. Lai, D. Weis, K. C. Welten, K. Nishiizumi, D. P. Glavin, J. P. Dworkin, C. M. O'D. Alexander, J. -A. Barrat, P. Haenecour, J. J. Barnes, A. N. Nguyen, H. C. Connolly Jr., D. S. Lauretta. 2026-10-22. Best Bulk Bennu (B3): Elemental compositions of aggregate samples from asteroid Bennu. https://arxiv.org/abs/2610.31828

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Saturn's Evolutionary History and Seismology: Survival of Deep Stably Stratified Regions in Evolutionary Models of Saturn Consistent with Ring Seismology

With recent advances in the modeling of the solar system giant planets, rapid progress has been made in understanding the remaining questions pertaining to their formation and evolution. However, this progress has largely neglected the significant constraints on the interior of Saturn's structure imposed by the observed oscillation frequencies in its rings. Here, we study initial conditions for Saturn's evolution that, after $4.56\;\mathrm{Gyr}$ of evolution, give rise to planetary structures admitting oscillation frequencies consistent with those observed via Saturn's ring seismology. Restricting our attention to models without compact rocky cores, we achieve simultaneous good agreement with most observed properties of Saturn at the level of current evolutionary models and with key frequencies in the observed oscillation spectrum. Our preliminary work suggests that Saturn's interior stably stratified region may be moderately less extended ($\sim 0.4$--$0.5R_{\rm Sat}$) than previously thought, which is important for reconciling the seismic constraints with evolutionary models. We also tentatively find that the deep helium gradients inferred by previous, static structural modelling of Saturn's ring seismology may not be required to reproduce the observed seismology data.

astro-ph.EP↗

arXiv2026

Addressing Exoplanetary Degeneracies Through Geometry: Application to Asynchronously Rotating Systems

This study augments the geometry-based InstellCa code that calculates accurate irradiance values to InstellCa--2, which computes the longitude averaged instellation over a given latitude on the planet along with its effective temperature profile. The estimation of instellation is performed considering the planet as a 3D body that asynchronously rotates, causing a varying zenith angle of the star resulting in a diurnal cycle. This serves as a specialised case study to demonstrate how the combination of this relative rotation and extreme proximity to host-stars can affect the estimated effective temperatures of close-in planets. 55 Cancri e is selected specifically to demonstrate the importance of this effect as it has been earlier hypothesised to exhibit asynchronous rotation and also has a debated scientific discourse about the existence of an atmosphere on the planet. The TRAPPIST-1 system, being a multi-planetary system susceptible to mean motion resonances, also serves as an interesting exemplar case to demonstrate these effects. Incorporating the stellar zenith angle to the geometrical analysis allows the possibility of physically feasible Bond albedo values that would otherwise be prohibited if a synchronously rotating bare rock scenario is assumed. Consequently, the degeneracies in the modelling of different atmospheric states of such planets can be reduced if the correct geometry is taken into account.

astro-ph.EP↗

arXiv2026

Update on the Orbital Motion of Encke's Periodic Comet: Nongravitational Deceleration Gradually Gaining

The end of an era in cometary astronomy --- as the transition from a nongravitational acceleration to a deceleration in the motion of Encke's comet was advertised in a paper of mine five years ago --- has now turned into a new era, as recent computations of the comet's nongravitational orbits performed independently by S. Nakano (CBAT) and by D. Farnocchia (JPL) appear to suggest. The new values of parameter A_2, compatible both with each other and with the earlier values in my previous paper, show that the magnitude of the deceleration has continued to grow. Critically assessed are the controversial computations at the Minor Planet Center, which contradict the above results and imply that Encke's comet was reverting to the acceleration. A plot of the number of observations used in the orbital solutions as a function of time shows an exponential rise following the introduction of CCD arrays, but not after use of photography became common five or six decades earlier. Dips in observer activity appear during the two World Wars. Because the comet has recently been observed along the entire orbit, the effective times that computed values of the nongravitational parameters apply to had to be redefined.

astro-ph.EP↗