1. Professor, Dept. of Civil, Architectural, and Environmental Engineering, Missouri Univ. of Science and Technology, 1401 N. Pine St., Rolla, MO 65409 (corresponding author).
2. Head, Spacecraft Technology Group, Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach Institute, Eckerstrasse 4, 79104 Freiburg, Germany.
3. Senior Scientist, Spacecraft Technology Group, Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach Institute, Eckerstrasse 4, 79104 Freiburg, Germany.