Grappler: Array of Bistable Elements For Pinching Net-Like Infrastructure to Low Gravity Bodies

Cherston, Juliana, Paul Strohmeier, and Joseph A. Paradiso. "Grappler: Array of Bistable Elements For Pinching Net-Like Infrastructure to Low Gravity Bodies." AIAA Scitech 2019 Forum. 2019.


Near-Earth asteroids and comets are ubiquitous and are key destinations for studying the formation of our solar system. These bodies may also one day serve as resource restocking depots for longer duration missions. However, in-situ scientific analysis requires the development of microgravity-tolerant landers that are not subject to recoil on impact. Whereas prior art focuses primarily on anchoring and hopping mechanisms, this paper evaluates a novel mission architecture in which chains of bistable pinching elements called grapplers are used to land net-like infrastructure on low gravity bodies. Unlike single-point-of-contact landers, a net that is successfully adhered to an asteroid may serve broad and flexible use in the exploration of small bodies. For example, it may constitute infrastructure to enable locomotion of a swarm of distributed crawling sensors and actuators for high resolution study of the body’s interior structure and surface properties. It may also serve as a foundation onto which larger scale sensing and communication structures can be built over time. Finally, it may serve as a series of hand holds used by astronauts to maneuver around the body. To adhere the net to a body, microgravity flight testing of a representative Grappler prototype demonstrates the tolerance of a bistable chain to variable impact conditions and terrain contours owing to the inherent adaptivity of the chain’s pinching configuration- for a chain of n bistable elements, 2 n pinching configurations are possible. These pinching elements can be integrated sparsely or densely into net-like infrastructure. A computational model is also presented. Grapplers are compared to alternative net adhesion strategies ranging from passive wrapping to chemical rigidization.

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