JPL Publication 08-24 A Chapman-Layers Ionospheric Model for Mars Xiaoqing Pi Charles D. Edwards George A. Hajj Chi Ao Larry J. Romans John L. Callas Anthony J. Mannucci Sami W. Asmar Daniel S. Kahan Jet Propulsion Laboratory National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California August 2008