Description: Mass and volume efficient solar arrays are sought by NASA, DoD and commercial space to enable high power missions from 20-30 kW up to 300 kW. Flexible substrate arrays can have higher specific power (W/kg) and specific volume (kW/m3) than conventional arrays. Typical designs for flexible substrate arrays require a stiff boom mechanism to deploy the array and provide the deployed structure. Graphite composite slit-tube booms are thermally stable and can enable next-generation flexible arrays by improving mass, volume, and cost. CTD has developed and demonstrated a 5cm diameter graphite composite slit-tube boom and canister designed for a 23m tether-stiffened solar array. The Stable Tubular Extendible Lock-Out Composite (STELOC) boom proposed here will feature two innovations to the composite slit-tube design that enhance stiffness. Slit-Lock interlocks the edges of the slit and Root-Lock eliminates the open section at the root of the boom when fully deployed. Combined, these innovations enable a 10cm STELOC boom that is much simpler, lighter, and stiffer than a 25cm diameter coilable longeron boom. This Phase I program will demonstrate a full length, 10cm STELOC boom including all innovative features to enhance stiffness. The program will also develop a conceptual design that meets all boom requirements provided by an identified spacecraft prime contractor for their flexible substrate array.

Benefits: Advancement of large deployable arrays is a critical requirement listed in NASA's technology roadmap. Power systems compromise nearly 30% of a spacecraft's mass on average, thus improvements in specific power (W/kg) will enable either a reduction in spacecraft mass or an increase in capabilities. Advanced arrays are required to enable scaling to larger array system up to 300 kW for interplanetary missions using solar electric power (SEP). A highly capable and inexpensive boom will enable these large, flexible substrate arrays.

Near term Air Force satellite missions require more capable solar arrays with more total power on the same platforms. Higher power solar arrays can leverage significant cost savings by enabling the GPS III Dual Launch variant, and they can overcome power challenges for Advanced EHF and classified missions. More powerful arrays must have an improved power to weight ratio, decreased stowage volume and increased deployed stiffness which are all enabled by the STELOC boom. Next-generation solar arrays are also intended for use on commercial geostationary satellites. Therefore, the requirements of these systems will be enveloped in the boom requirements considered during Phase I.