Using Geological Implications of a Physical Libration to Constrain Enceladus’ Libration State

1 , B.G. Bills 2,3 , P. Helfenstein 4 , R. Greenberg 5 , G.V. Hoppa 6 and D.P. Hamilton 7 , 1 Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. 2 Institute for Geophysics and Planetary Physics, Scripps Institution of Oceanography, La Jolla, CA 92093, USA, 3 Jet Propulsion Laboratory, Pasadena, CA 91109, USA. 4 CRSR, Cornell University, Ithaca, NY 14853, USA. 5 Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA. 6 Raytheon, Woburn, MA 01801, USA. 7 Department of Astronomy, University of Maryland, College Park, MD 20742, USA.