WRANGLER: Nanosatellite Architecture for Tethered De-Spin of Massive Asteroids

In order to provide a feasible solution for the capture and de-spin of massive asteroids Tethers Unlimited, Inc. has developed an architecture and conceptual design for a nanosatellite-scale system, called Weightless Rendezvous And Net Grapple to Limit Excess Rotation (WRANGLER). WRANGLER uses a tethered nanosatellite to de-spin a targeted asteroid by converting the asteroid’s rotational momentum into rotation momentum of the nanosatellite as it revolves around the asteroid, much in the same manner a de-spin yo-yo device slows the rotation of an upper stage rocket. The leverage offered by using a tether to extract angular momentum from a rotating asteroid enables a very small nanosatellite system (1 kg) to despin a very massive asteroid (> 1,000t). A detailed analysis of the tether deployment and nanosatellite dynamics associated with de-spinning an asteroid demonstrated that a tethered system can de-spin and de-tumble large space objects while avoiding tether wrapping and other dynamic problems. We have developed architectures for nanosatellite-scale asteroid capture and de-spin systems and shown that these architectures provide significant size, weight, and power savings over baseline propellant-based de-spin approaches for the majority of identified near earth objects. Finally, we have exploited the parallels between the problem of asteroid retrieval and the challenges faced by prospective active debris removal missions to propose a debris remediation architecture utilizing WRANGLER technologies to enable affordable debris removal with microsatellite-scale spacecraft.