Description: In response to the need for an affordable exoplanet-analysis science mission, NASA has recently embarked on the ROSES Technology Development for Exoplanet Missions (TDEM) program to develop a large deployable starshade (external occulter) with adequate manufacturing, deployment precision and stability. To that end NASA-JPL is involved in an ongoing effort to design and demonstrate a full-scale (30-32m diameter) starshade which utilizes a radially deploying and optically precise perimeter truss with 28 circumferentially mounted petals. The perimeter truss structure deploys from an initial diameter of 3 m to 20 m and is configured much like a bicycle wheel when deployed in that the only components connecting the center structural hub to the perimeter truss are a series of spokes, which largely determine the deployed shape of the ring truss and petals. In addition the spoke component must also bend and fold to a tight radius upon packaging for launch. Although high performance carbon fiber cable has been used for space applications in the past, there are no commercially available cable products with the specifications necessary for this starshade application. To meet the needs of the starshade system, Roccor proposes to develop a Dimensionally-Stable Structural Space Cable (DS3 Cable) consisting of advanced fibers that enable linear and consistent behavior at very low operational tensions as well as a near-zero coefficient of thermal expansion (CTE). This work will also address feasibility concerns with manufacturing consistency and package-ability by fabricating a large quantity of test articles for evaluation at JPL. The DS3 cable is widely applicable to many variants of precision space deployable structures and will be made commercially available for alternative uses.

Benefits: The development of Dimensionally-Stable Structural Space Cable has numerous applications to both current and future NASA development efforts. Most notably, this component is of critical importance for a starshade (external occulter) conceptual development effort currently underway at JPL. Other applications related to large deployable truss structures requiring tight packaging constraints, low response to thermal gradients and linear precision at low operational tensions.

Roccor has received interest from several commercial entities for Dimensionally-Stable Structural Space Cable. Of particular note, high precision and thermally stable wire is being actively sought out to support development of high gain, deployable mesh antennas. Other terrestrial applications to support precision structures and optical surfaces are of interest as well.