1. Alan Levin Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, Kansas 66506, USA
2. Space Radiation Analysis Group, NASA Lyndon B. Johnson Space Center, Houston, Texas 77058, USA
3. Department of Civil and Environmental Engineering, University of Utah, Salt Lake City, Utah 84112, USA
4. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA