Robotic Augmentation of EVA for Hubble Space Telescope Servicing

Abstract

The University of Maryland Space Systems Laboratory has developed the Ranger Telerobotic Shuttle Experiment, which was intended to be an initial flight demonstration of dexterous robotics for space operations. Ranger TSX incorporates advanced robotic manipulators capable of using EVA interfaces and performing EVA tasks, and was intended for a space shuttle test flight in 2004 prior to recent programmatic cutbacks. To better quantify the impact of Ranger-level dexterous robotics on space operations, Hubble Space Telescope servicing was adopted as a set of reference missions. This was a logical decision, since Ranger was designed to be as capable as an astronaut in extravehicular activity (EVA), and several of the Ranger experimental tasks were directly taken from HST servicing experience. HST EVA operations from the first four servicing missions were broken down into tasks, subtasks, and primitives, and were evaluated for telerobotic operations. For each candidate, the primitives were quantified in terms of what percentage could be performed by a robot, and whether robotic operations were best performed before, during, or after the EVA operations. Initial resulted indicated that, for the first servicing mission, a single robotic assistant for the EVA crew would increase productivity by 60%. This would allow the five EVAs of SM-1 to be performed in three, or would allow the equivalent of three more EVA-only operational days to be included in five EVA sorties for the human/robot team activities. Further analysis of later missions, which had fewer contingency operations, showed that up to 80% of the EVA tasks could have been reassigned to the robot. This paper presents the results of this analysis, along with further research into specific interfaces required for telerobotic operations, and more global redesign of mission operations to optimize performance of the human/robotic teams.