Enhanced performance for the manned maneuvering unit

Abstract

We have all seen the Manned Maneuvering Unit (MMU) on television, in the newspaper, magazines and any number of other places. It is probably one of the most widely recognized articles ever put into orbit. This paper briefly describes the MMU. The description includes an overview of the controls and physical features and a discussion of the propulsion and electrical systems. Operational experience to date is briefly covered. The MMU was first used on STS 41-B for the first untethered space walk on February 7, 1984. Next usage was for the Solar Max mission on STS 41-C, followed by the retrieval of the Westar and Palapa communication satellites on mission STS 51-A in November, 1984. One of the “lessons learned” during these space operations was the need for enhanced performance by the MMU, and leads into a discussion of how that increased performance capability will be provided. Current work on a Propellant Tank Kit (PTK), which will provide enhanced performance, is shown. The PTK will provide sufficient propellant storage capability such that the MMU with PTK will have twice the previous delta velocity capability; i.e., double the MMU's maneuvering ability. Results of development testing in the NASA/JSC Weightless Environment Test Facility are included. Current status of PTK development is presented. This paper ends with a brief discussion of proposed space operations using the enhanced MMU performance in erecting space structures from the Space Shuttle, assembling and maintaining Space Station, rescue-transfer of astronauts and other space operations.