Impact excavation on asteroid 4 Vesta: Hubble Space Telescope results Thomas, P. C. ; Binzel, R. P. ; Gaffey, M. J. ; Storrs, A. D. ; Wells, E. N. ; Zellner, B. H. Abstract Publication: Science Pub Date: September 1997 DOI: 10.1126/science.277.5331.1492 Bibcode: 1997Sci...277.1492T