1. R. P. Binzel, S. J. Bus, T. H. Burbine, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
2. J. M. Sunshine, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, and Science Applications International Corporation, 4501 Daly Drive, Chantilly, VA 22021, USA.