Spectral and spin measurement of two small and fast-rotating near-Earth asteroids

• Main Authors: Polishook, David (Contributor), Binzel, Richard P. (Contributor), Lockhart, Matthew (Contributor), DeMeo, Francesca E. (Contributor), Golisch, W. (Author), Bus, S. J. (Author), Gulbis, Amanda A. S. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences (Contributor)
• Format: Article
• Language: English
• Published: Elsevier B.V., 2014-03-06T20:56:49Z.
• Subjects: Article
• Online Access: Get fulltext

 In May 2012 two asteroids made near-miss "grazing" passes at distances of a few Earth-radii: 2012 KP24 passed at 9 Earth-radii and 2012 KT42 at only 3 Earth-radii. The latter passed inside the orbital distance of geosynchronous satellites. From spectral and imaging measurements using NASA's 3-m Infrared Telescope Facility (IRTF), we deduce taxonomic, rotational, and physical properties. Their spectral characteristics are somewhat atypical among near-Earth asteroids: C-complex for 2012 KP24 and B-type for 2012 KT42, from which we interpret the albedos of both asteroids to be between 0.10 and 0.15 and maximum effective diameters of 20 ± 6 and 6 ± 1 m, respectively. Among B-type asteroids, the spectrum of 2012 KT42 is most similar to 3200 Phaethon and 4015 Wilson-Harrington. Not only are these among the smallest asteroids spectrally measured, we also find they are among the fastest-spinning: 2012 KP24 completes a rotation in 2.5008 ± 0.0006 min and 2012 KT42 rotates in 3.634 ± 0.001 min.