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Human factors will have a profound impact on aerobrake designs of future Space Transfer Vehicles to allow the vehicles to be assembled, maintained, and refurbished on orbit. Though deployable aerobrake designs are being considered, many extravehicular activity tasks will be a necessary part of assembly and refurbishment. Crew interfaces will need to be easily operated by a suited crewman during all phases of flight. While telerobotic and autonomous systems may be developed for portions of these tasks, extravehicular activity will always be required for contingency plans. This paper details some of the critical human factor issues that must be addressed in aerobrake design based on results from aerobrake neutral buoyancy test performed in October 1990 under the McDonnell Douglas Space Systems Company Independent Research and Development program. This paper examines the need for crew restraint during assembly for torque reaction, familiar frame of reference, and speed of assembly.

As the US expands its presence in space, NASA/DOD requirements to assemble, operate, and maintain facilities in the vacuum of space will grow. Space Station Freedom (SSF) studies have shown that projected requirements for extravehicular activity (EVA) are significantly greater than the capabilities presently planned. Although the SSF design is currently being restructured by NASA with the intent of relieving its requirements for EVA, the limited availability of EVA crew time is still a critical and limiting resource to future growth and expansion. This paper details approaches to advancing extravehicular capability through EVA tools such as telerobotics and free-flyers to ensure the feasibility of assembly and maintenance of large space structures. We detail these approaches through results from aerobrake and propellant tank farm neutral buoyancy testing undertaken by McDonnell Douglas Space Systems Company (MDSSC) Independent Research and Development (IRAD).

Extravehicular activity (EVA) will be required in future space missions for on-orbit assembly, maintenance, and servicing of space vehicles. Current EVA activities rely extensively on the use of EVA crew members for the assembly, maintenance and repair of space vehicles, satellites and structures, consequently exposing them to a variety of hazards, ranging from radiation and impacting debris to physiological dangers, such as bends and air embolisms. Relieving the crew members of dangerous or time-consuming EVA tasks by allowing routine or hazardous EVA operations to be conducted by a telerobotic device would be a significant advance in EVA technology. Properly incorporated telerobotic devices will shorten operational performance schedules, increase crewmember safety, and reduce staffing requirements, thereby increasing the performance of future space systems.

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.