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Assembly and maintenance of the International Space Station (ISS) relies heavily on the use of extravehicular robotic systems. When fully assembled the ISS robotics complement will include three main manipulators, two small dexterous arms, and a mobile base and transporter system. The complexity and mobility of the systems and limited opportunities for direct viewing of the Space Station's exterior makes telerobotic operations an especially challenging task. Although fundamental manipulator design, control systems, and strategies for autonomous versus manual control vary greatly between the systems, commonality in the design of workstation controls and displays is considered essential to enhance operator performance and reduce the possibility of errors. Principal human factors opportunities are associated with workstation layout, human-computer interface considerations, adequacy of alignment cues for maintenance of safe approach corridors during mating tasks, spatial awareness challenges, integration of supplemental computer graphic displays to enhance operator global situational awareness, and training methodologies for preservation of critical skills during long-duration missions.

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Sixteen male subjects of varying age and anthropometric characteristics were each asked to perform a seriesof parcelhandlingactivitiesat an 'habitual' ratefor 2 h. Work rate and oxygen consumption were monitored for the various task components which werearranged to enable carryover effects to be investigated. The results indicated that an energy output of between 400 Wand 500 W could be considered as being 'habitual' for this form of iask. However in submaximal tasks of this nature anthropometric factors are likely [0 playa greater part in determiningenergy expenditure than age or work rate factors as work rate is largelyinfluenced by the interaction between anthropometric characteristics and workplace design. I. IntroductionSince the work of Taylor in 1913,job evaluation and design issues have been based on scientific estimates of physical work load.In practice these estimates are derived from analyses of the physicalcharacteristics of the task, time studies of experienced workers and subjective ratings of effort. The estimates may be supported by evidence from work physiology, laboratory studies involving a variety of methods of controlling physical work output (treadmills etc.) and a variety of physiological indices based on heart rate, respiratory function and biochemical analyses (Crowden 1932, Astrand and Rodahl 1977).The bridge between the laboratory and practice is associated with conflicting problems of reliability and validity. However an increasing number of bridging studies are being reported which make use of sophisticated equipment and statistical design facilities and which can achieve credibility by both researchers and practitioners. Snook (1978) reported the results of extensive psychophysical studies for estimating acceptable weights and forces in materials handling using task durations ofabout 4·5 h. Heart rate methods were used by Rodahl and Vokac(1977) for the study of the habitual work stress to trawlermen. Because of the inherent variability of the work performed by trawlermen a wide range in heart rates was observed but mean rates of just over 100 beats min -1 were found for deckhands during their working period. Htay (1978) also used heart rate methods to observe the habitual physical activities of rural Burmese women. These authors used a diary method of estimating the proportions of time spent on different activities at different times of the year and then sampled heart rates for particular activities. During certain periods of the year it was implied that mean heart rates of 130 beats min-1 were maintained for long periods during the activity of 'pounding glutinous paddy seeds'.The stability advantages of oxygen uptake methods were preferred by Haisman et al. (1972) in a study of handcart pushing. In this study work periods ofJO min were used and energy expenditure values of about 510 W were observed for both treadmill and outdoor circuits. Similar methods were used by Datta et al. (1978) in a study of rickshaw pulling with similar energy expenditure results. However Nag et al. (19...