The Open UniversitySkip to content
 

Spectral slope variations for OSIRIS-REx target Asteroid (101955) Bennu: Possible evidence for a fine-grained regolith equatorial ridge

Binzel, Richard P.; DeMeo, Francesca E.; Burt, Brian J.; Cloutis, Edward A.; Rozitis, Ben; Burbine, Thomas H.; Campins, Humberto; Clark, Beth E.; Emery, Joshua P.; Hergenrother, Carl W.; Howell, Ellen S.; Lauretta, Dante S.; Nolan, Michael C.; Mansfield, Megan; Pietrasz, Valerie; Polishook, David and Scheeres, Daniel J. (2015). Spectral slope variations for OSIRIS-REx target Asteroid (101955) Bennu: Possible evidence for a fine-grained regolith equatorial ridge. Icarus, 256 pp. 22–29.

DOI (Digital Object Identifier) Link: https://doi.org/10.1016/j.icarus.2015.04.011
Google Scholar: Look up in Google Scholar

Abstract

Ongoing spectroscopic reconnaissance of the OSIRIS-REx target Asteroid (101955) Bennu was performed in July 2011 and May 2012. Near-infrared spectra taken during these apparitions display slightly more positive ("redder") spectral slopes than most previously reported measurements. While observational systematic effects can produce such slope changes, and these effects cannot be ruled out, we entertain the hypothesis that the measurements are correct. Under this assumption, we present laboratory measurements investigating a plausible explanation that positive spectral slopes indicate a finer grain size for the most directly observed sub-Earth region on the asteroid. In all cases, the positive spectral slopes correspond to sub-Earth latitudes nearest to the equatorial ridge of Bennu. If confirmed by OSIRIS-REx in situ observations, one possible physical implication is that if the equatorial ridge is created by regolith migration during episodes of rapid rotation, that migration is most strongly dominated by finer grain material. Alternatively, after formation of the ridge (by regolith of any size distribution), larger-sized equatorial material may be more subject to loss due to centrifugal acceleration relative to finer grain material, where cohesive forces can preferentially retain the finest fraction (Rozitis, B., Maclennan, E., Emery, J.P. [2014]. Nature 512, 174-176).

Item Type: Journal Item
Copyright Holders: 2015 Elsevier Inc.
ISSN: 0019-1035
Keywords: asteroids; asteroid surfaces; regolith; spectroscopy
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 44978
Depositing User: Benjamin Rozitis
Date Deposited: 11 Dec 2015 10:03
Last Modified: 07 Dec 2018 10:37
URI: http://oro.open.ac.uk/id/eprint/44978
Share this page:

Metrics

Altmetrics from Altmetric

Citations from Dimensions

Actions (login may be required)

Policies | Disclaimer

© The Open University   contact the OU