Deployable structures mission in medium earth orbit

The Air Force Research Laboratory (AFRL) Space Vehicles Directorate has developed a mission to research the technologies needed for large space structures, high-power generation, and protection of space assets within the high radiation environment of a medium earth orbit (MEO). The resulting Deployable Structures Experiment (DSX) will address a number of basic science experiments via a single MEO testbed platform. The DSX concept, with specific emphasis on scientific merit, relevance to the Air Force needs, and necessity for flight demonstration, was conceived and proposed for further development in mid-2003. The program then went through 8 months of proposal and review, maturing the overall design, scientific merit and payoff, and Air Force relevance. Ultimately, of the six proposed concepts, DSX was selected in January 2004 as the next AFRL/VS basic research flight experiment. During 2004 the DSX concept was refined, with specific focus on requirement derivation and allocation to hardware and software solutions. The DSX mission, matured in parallel, is the primary subject of this paper. The baseline DSX experiment should be launch ready by late 2009, with at least one year of on-orbit operations scheduled. DSX comprises five research experiments, that paves the way for new Department of Defense (DoD) capabilities in space surveillance, microsats with large aperture and power, and protection of space assets from natural and enhanced radiation environments. The DSX experiments include research on: 1) Transformational deployed structures: the deployment, dimensional stability, and MEO environment degradation of large deployable space structures. 2) Adaptive control of structures: the on-orbit system identification (SysID) of the dynamics of these large deployable structures and the use of multiple-input-multiple-output (MIMO) autonomous adaptive control techniques. 3) Radiation belt remediation: The physics of very low frequency (VLF, 3-30 kHz) electromagnetic wave i- - njection from ground-based transmitters, propagation, and wave-particle interactions in the magnetosphere relevant to radiation-belt remediation (RBR) techniques. 4) Lightweight, high-power, thin-film photovoltaics: the performance, radiation tolerance, plasma interactions, and thermal annealing of thin-film photovoltaics (TF-PV) in a MEO environment. 5) Space weather: The detailed measurement and mapping of energetic particle and plasma distributions in the poorly characterized MEO environment. Successful completion of the DSX mission will assist in removing power, aperture, and the MEO environment as significant design constraints for future space systems