TY - JOUR
T1 - Asteroid (101955) 1999 RQ36
T2 - Spectroscopy from 0.4 to 2.4μm and meteorite analogs
AU - Clark, Beth Ellen
AU - Binzel, Richard P.
AU - Howell, Ellen S.
AU - Cloutis, Edward A.
AU - Ockert-Bell, Maureen
AU - Christensen, Phil
AU - Barucci, Maria Antonietta
AU - DeMeo, Francesca
AU - Lauretta, Dante S.
AU - Connolly, Harold
AU - Soderberg, Alicia
AU - Hergenrother, Carl
AU - Lim, Lucy
AU - Emery, Josh
AU - Mueller, Michael
PY - 2011/12
Y1 - 2011/12
N2 - We present reflectance spectra from 0.4 to 2.4μm of Asteroid (101955) 1999 RQ36, the target of the OSIRIS-REx spacecraft mission. The visible spectral data were obtained at the McDonald Observatory 2.1-m telescope with the ES2 spectrograph. The infrared spectral data were obtained at the NASA Infrared Telescope Facility using the SpeX instrument. The average visible spectrum is combined with the average near-infrared wavelength spectrum to form a composite spectrum. We use three methods to constrain the compositional information in the composite spectrum of Asteroid (101955) 1999 RQ36 (hereafter RQ36). First, we perform a least-squares search for meteorite spectral analogs using 15,000 spectra from the RELAB database. Three most likely meteorite analogs are proposed based on the least-squares search. Next, six spectral parameters are measured for RQ36 and their values are compared with the ranges in parameter values of the carbonaceous chondrite meteorite classes. A most likely meteorite analog group is proposed based on the depth of overlap in parameter values. The results of the least-squares search and the parametric comparisons point to CIs and/or CMs as the most likely meteorite analogs for RQ36, and COs and CHs as the least likely. RQ36 has a spectrally " blue" continuum slope that is also observed in carbonaceous chondrites containing magnetite. We speculate that RQ36 is composed of a " CM1" -like material. Finally, we compare RQ36 to other B-type asteroids measured by Clark et al. (Clark, B.E. et al. [2010]. J. Geophys. Res. 115, E06005). The results of this comparison are inconclusive. RQ36 is comparable to Themis spectral properties in terms of its albedo, visible spectrum, and near-infrared spectrum from 1.1 to 1.45μm. However, RQ36 is more similar to Pallas in terms of its near-infrared spectrum from 1.6 to 2.3μm. Thus it is possible that B-type asteroids form a spectral continuum and that RQ36 is a transitional object, spectrally intermediate between the two end-members. This is particularly interesting because Asteroid 24 Themis was recently discovered to have H2O ice on the surface (Rivkin, A., Emery, J. [2010]. Nature 464, 1322-1323; Campins, H. et al. [2010a]. Nature 464, 1320-1321).
AB - We present reflectance spectra from 0.4 to 2.4μm of Asteroid (101955) 1999 RQ36, the target of the OSIRIS-REx spacecraft mission. The visible spectral data were obtained at the McDonald Observatory 2.1-m telescope with the ES2 spectrograph. The infrared spectral data were obtained at the NASA Infrared Telescope Facility using the SpeX instrument. The average visible spectrum is combined with the average near-infrared wavelength spectrum to form a composite spectrum. We use three methods to constrain the compositional information in the composite spectrum of Asteroid (101955) 1999 RQ36 (hereafter RQ36). First, we perform a least-squares search for meteorite spectral analogs using 15,000 spectra from the RELAB database. Three most likely meteorite analogs are proposed based on the least-squares search. Next, six spectral parameters are measured for RQ36 and their values are compared with the ranges in parameter values of the carbonaceous chondrite meteorite classes. A most likely meteorite analog group is proposed based on the depth of overlap in parameter values. The results of the least-squares search and the parametric comparisons point to CIs and/or CMs as the most likely meteorite analogs for RQ36, and COs and CHs as the least likely. RQ36 has a spectrally " blue" continuum slope that is also observed in carbonaceous chondrites containing magnetite. We speculate that RQ36 is composed of a " CM1" -like material. Finally, we compare RQ36 to other B-type asteroids measured by Clark et al. (Clark, B.E. et al. [2010]. J. Geophys. Res. 115, E06005). The results of this comparison are inconclusive. RQ36 is comparable to Themis spectral properties in terms of its albedo, visible spectrum, and near-infrared spectrum from 1.1 to 1.45μm. However, RQ36 is more similar to Pallas in terms of its near-infrared spectrum from 1.6 to 2.3μm. Thus it is possible that B-type asteroids form a spectral continuum and that RQ36 is a transitional object, spectrally intermediate between the two end-members. This is particularly interesting because Asteroid 24 Themis was recently discovered to have H2O ice on the surface (Rivkin, A., Emery, J. [2010]. Nature 464, 1322-1323; Campins, H. et al. [2010a]. Nature 464, 1320-1321).
KW - Asteroids
KW - Asteroids, Composition
UR - http://www.scopus.com/inward/record.url?scp=80054916700&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=80054916700&partnerID=8YFLogxK
U2 - 10.1016/j.icarus.2011.08.021
DO - 10.1016/j.icarus.2011.08.021
M3 - Article
AN - SCOPUS:80054916700
SN - 0019-1035
VL - 216
SP - 462
EP - 475
JO - Icarus
JF - Icarus
IS - 2
ER -