Inflatable-Rigidizable Solar Concentrators for Space Power Applications

This paper summarizes the development of L’Garde’s Long Lived Solar Concentrator technology which utilizes material rigidization methods to provide a long lasting reflector shape without requiring continuous inflation. Material studies were conducted and testing completed on 1 m reflectors to down select work-hardening of an aluminum/plastic laminate as the rigidization method of choice over cold rigidization of a Kevlar®/thermoplasticelastomer composite. The results of the surface measurements are summarized showing slope errors as low as 12 milliradian and a focal dot with a radius as small as 37 mm. Two 3m reflectors were constructed with one tested by photogrammetry and the results compiled while the second is packaged for future testing at NASA Glenn’s Tank 6 Solar Simulator facility. Significant sciential data were collected through testing which showed that even when subjected to 1 g earth loading conditions, the shape of the reflector could be maintained allowing for future ground testing of the concept. The result is an advanced concept poised for continued development. The results of a system study using this technology are summarized and give guidance to properly sizing and positioning the reflector system on a spacecraft. The heart of this technology advancement resides in its mission enabling capability. This technology advancement diminishes two hurdles for large power concentration. First, rigid mirror reflectors require large spaces to stow thereby limiting the aperture size of the concentrator. Second, purely inflatable reflectors will require some make-up gas to remain inflated in space subsequently limiting the mission lifetime. Lastly, a novel approach to remove the reflector canopy, further improving the performance of the reflector, was developed and tested on the 3 m reflector. This would remove the transmission losses that would occur when collecting the solar energy and remove the need to find a canopy material that wouldn’t darken over the life of the reflector system.