@article{bc52580f36214b079a725067a3df971a,
title = "Photometry of asteroid (101955) Bennu with OVIRS on OSIRIS-REx",
abstract = "NASA's OSIRIS-REx spacecraft arrived at its sampling target, asteroid (101955) Bennu, in December 2018 and started a series of global observation campaigns. Here we investigate the global photometric properties of Bennu as observed by the OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS) over the time period December 9, 2018, to September 26, 2019. In this study we used observations obtained over wavelengths ranging from 0.4 to 3.7 μm, with a solar phase angle range of 5.3° to 132.6°. Our aim is to characterize the global average disk-resolved photometric properties of Bennu with multiple models. The best-fit model is a McEwen model with an exponential phase function and an exponential polynomial partition function. We use this model to correct the OVIRS spectra of Bennu to a standard reference viewing and illumination geometry at visible to infrared wavelengths for the purposes of global spectral mapping. We derive a bolometric Bond albedo map in which Bennu's surface values range from 0.021 to 0.027. We find a phase reddening effect, and our model is effective at removing this phase reddening. Our average model albedo shows a blueish spectrum with a > 10% absorption feature centered at 2.74 μm. Of all comparisons with previously visited asteroids and comets, only 28P/Neujmin, 2P/Encke, and (162173) Ryugu are darker than Bennu. We find that Bennu is a few percent brighter than Ryugu in the wavelengths respectively observed by the OSIRIS-REx and Hayabusa2 missions (from 0.48 to 0.86 μm). We also compare our spectroscopic photometry of Bennu with the OSIRIS-REx imaging photometry and with ground-based predictions.",
keywords = "Asteroid Bennu, Asteroid surfaces, Photometry, Spectrometer",
author = "Zou, {Xiao Duan} and Li, {Jian Yang} and Clark, {Beth E.} and Golish, {Dathon R.} and Salvatore Ferrone and Simon, {Amy A.} and Reuter, {Dennis C.} and Domingue, {Deborah L.} and Hannah Kaplan and Barucci, {Maria Antonietta} and Sonia Fornasier and Alice Praet and Hasselmann, {Pedro Henrique} and Bennett, {Carina A.} and Cloutis, {Edward A.} and Eri Tatsumi and DellaGiustina, {Daniella N.} and Lauretta, {Dante S.}",
note = "Funding Information: This material is based upon work supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program. We are grateful to the entire OSIRIS-REx Team for making the encounter with Bennu possible and the exploration highly successful. X.-D. Zou and J.-Y. Li also acknowledge partial support from the Solar System Exploration Research Virtual Institute 2016 ( SSERVI16 ) Cooperative Agreement (Grant NNH16ZDA001N ), SSERVI-TREX to the Planetary Science Institute. M. A. Barucci acknowledges funding support from CNES . We also thank Heather Roper for providing the mission phase observational strategy figure. Funding Information: This material is based upon work supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program. We are grateful to the entire OSIRIS-REx Team for making the encounter with Bennu possible and the exploration highly successful. X.-D. Zou and J.-Y. Li also acknowledge partial support from the Solar System Exploration Research Virtual Institute 2016 (SSERVI16) Cooperative Agreement (Grant NNH16ZDA001N), SSERVI-TREX to the Planetary Science Institute. M. A. Barucci acknowledges funding support from CNES. We also thank Heather Roper for providing the mission phase observational strategy figure. OVIRS [Level 3c] data (inputs to our modeling) are available in the Planetary Data System at https://sbn.psi.edu/pds/resource/orex/ovirs.html (Reuter et al. 2019). Data are delivered to the PDS according to the schedule in the OSIRIS-Rex Data Management Plan (https://sbnarchive.psi.edu/pds4/orex/orex.mission/document/) (Crombie and Selznick, 2019). Publisher Copyright: {\textcopyright} 2020",
year = "2021",
month = apr,
doi = "10.1016/j.icarus.2020.114183",
language = "English (US)",
volume = "358",
journal = "Icarus",
issn = "0019-1035",
publisher = "Academic Press Inc.",
}