Solar sail structural characterization test program

The NASA in-space propulsion program sponsored intensive solar-sail technology and systems design, development, and hardware demonstration activities over the past three years. Efforts to validate an ATK Space Systems designed scalable solar sail system by functional demonstration in relevant environments, together with structural test-analysis correlation activities have recently been successfully completed. The tests spanned three phases of the program, with each phase lasting approximately I year; phase 1 focused on component tests of a mast segment and sail quadrant, phase 2 focused on a 10-m quadrant with two supporting masts, and phase 3 focused on a 20-m sail system with all four quadrants and masts. These tests were conducted for the purpose of validating analytical models that would be required by a flight test program to predict in-space performance. Specific tests included static shape testing using photogrammetry and modal vibration tests on the sail in a 1 torr vacuum environment using various excitation locations and techniques. The excitation methods were evaluated for their applicability to in-vacuum ground testing and their traceability to the development of on-orbit flight test techniques. The solar-sail masts were modal vibration tested in ambient atmospheric conditions and these results are also discussed.