Free-Flyers for Space Station EVA Operations

Recent telerobotic research has included the construction and testing of free-flyers with specific missions. The Manned Maneuvering Unit (MMU) was developed for short, manned excursions in space. The Orbital Maneuvering Vehicle (OMV) was developed for servicing and reboost of satellites. The Beam Assembly Teleoperator (BAT) was developed at the Massachusetts Institute of Technology(MIT) and is presently being improved upon at the University of Maryland under NASA code R for the purpose of truss assembly. The need for free-flying vehicles will increase as humans spend more time working in space, particularly in the field of space construction. Although simple translation along the Station truss can easily be accomplished using the Crew and Equipment Translation Aid (CETA) rails or the Mobile Transporter (MT), translation to the ends of solar arrays and parts of large structures being serviced or assembled is more difficult. Translation to co-orbiting platforms and satellites for repair or inspection is not feasible without free-flyer capability. Many of these issues, as well as free-flyer designs, are being researched under a McDonnell Douglas independent research and development (IRAD) project. This paper examines the advantages of free-flyers to on-orbit operations, focusing on some free-flyers presently under development. Issues for further study, such as those concerning free-flyer applications to increase EVA efficiency and to support space station evolution, are identified.