EVA Operational Enhancements and ASEM

Among the many firsts which will occur on STS-49, the maiden voyage of the Space Shuttle Endeavour, a Space Station Freedom (SSF) experiment entitled Assembly of Station by Extravehicular Activity (EVA) Methods (ASEM) promises to test the boundaries of EVA operational capabilities. Should the results be favorable, station and other major users of EVA stand to benefit from increased capabilities. Even the preparation for the ASEM experiment is serving as a pathfinder for complex SSF operations. This paper reviews the major tasks planned for ASEM and discusses the operational analogies investigators are attempting to draw between ASEM and SSF. How these findings may be applied to simplify station assembly and maintenance will also be discussed.

Operational demonstrations planned for ASEM and their potential applications include:

• EVA positioning and installation of a large mass, such as an SSF pallet, which has been transported by a robotic device, to a rigid structure
• EVA handling, including removal, transport, fine positioning, and installation, of components weighing up to 4000 lb by a crewmember working from a foot restraint attached to a robotic manipulator
• Evaluation of simple concepts and techniques that could assist EVA crewmembers in self-rescue or, possibly, equipment transfer
• Assessment of working conditions such as lighting, field of view, thermal comfort, and management of antennas and the reaction control system while EVA crewmembers are above the forward portion of the orbiter, in the region where SSF will be assembled
• Use of an EVA helmet-mounted TV view or of EVA verbal guidance as a substitute for direct and specialized TV views for intravehicular (IV) controlled robotic berthing of a payload

Even though the mission will not be flown until the middle of 1992, development and training activities are resolving several puzzling issues and revealing some tentative results. This paper will describe some of the lessons learned to date.