Maturing Microspine Grippers for Space Applications through Test Campaigns

Abstract

This paper presents the maturation of Microspine Grippers for use in space, including for NASA's Asteroid Redirect Mission. Microspine Grippers use hundreds or thousands of sharp hooks to grip small asperities on the surface of a rock. Key to achieving a good grip, the hooks must independently conform to the surface of the rock, which has roughness at many length scales. Since each hook supports a load of only a few Newtons, the microspines must be able to move relative to their neighbors to share the overall gripping load between many contact points distributed around the gripper. The gripper only requires around 10% of the hooks to catch an asperity to achieve a strong grip. The results of multiple test campaigns to mature and characterize microspine technology are presented. These tests included field trials on a variety of rock types in Hawaii and New Mexico as well as a laboratory campaign that used a Motoman MH50 industrial robot arm and a variety of asteroid boulder analog materials and operational scenarios. Additional test results from a zero-gravity flight campaign aboard NASA's C9 Reduced Gravity Airplane are presented. Microspine Grippers were also tested during NEEMO 20 (NASA Extreme Environment Mission Operations), where they were used by astronauts in neutral buoyancy simulating a manned mission to the surface of Phobos. Finally, results from tests with single microspines are presented from a thermal chamber campaign and from experiments on Tagish Lake meteorites, a unique meteorite with very low strength from a C-type asteroid.