Design & Feasibility Study of Kilometer-Scale Towed-Body Deployment & Retraction

NASA’s Jet Propulsion Laboratory (JPL) is building a proposal for a prolonged aerial robotic mission to explore Venus, its atmosphere, and its surface using an altitude-controlled balloon platform known as an Aerobot. The mission’s longevity necessitates operation within the Venusian cloud-layer, between 47km and 52km altitudes, where visible-spectrum surface imagery is impossible. To overcome this issue, researchers have proposed a system that lowers a towed-body several kilometers below the cloud-layer. This paper details the design and properties of such a system for use on an Earth-analog balloon platform. This work was conducted to mature the technological readiness of a km-scale deployable aerodynamic body, which can be repeatedly lowered and retracted by a winch system. Numerical methods are used to determine the sufficient capabilities of a winch system which can accommodate a 1⁄2 scale towbody, and a working prototype of both is produced. Emphasis is placed on an adaptable design capable of testing numerous configurations of key aerodynamic and tether-winding parameters, thus serving as a platform from prolonged testing of towed-body systems including their dynamics, stability, and efficiency. The next step beyond this work is flight-testing on the near-km scale in relevant conditions on a balloon within the Earth’s atmosphere, which will provide confidence in JPL's mission architecture for application to Venus.