Human Performance During a Short- and a Long-Term Stay in Space

During short- and long-term space missions cosmonauts are exposed to several physical, mental, and emotional stressors (e.g., microgra- vity, enhanced noise levels, disturbed sleep, confinement, reduced social contacts) which may impair their performance capabilities. To analyze the impact of the space environment on cognitive, visuo- motor, and time-sharing performance a (1) German cosmonaut was as- sessed repeatedly during a short-term (8 days) space flight, and (2) a Russian cosmonaut was assessed during the first four month of his long-term (14 months) stay onboard MIR station. A subset of tasks of the AGARD battery of Standardized Tests for Research with Environmental Stressors (STRES, AGARD, 1989) was used for that purpose. Cognitive performance was probed by a Grammatical Reasoning Task and two versions of a Sternberg Memory Search Task differing in memory load. Fine manual control performance was assessed by an Unstable Tracking Task. Time-sharing performance was analyzed by dual-task combinationsof Unstable Tracking with concurrent Memory Search. During the long-term single case study the subjective workload of the cosmonaut experienced during task performance was assessed by the NASA Task Load Index (TXL). Results: Whereas basic cognitive operations (memory search, logical reasoning) were almost unimpaired, significant decrements of visuo-motor performance (tracking) occured in both studies. Recovery was found immediately back on Earth (first study), and after approximately three weeks in space (second study). Subjective effort ratings as well as ratings of mental and physical task demands were elevated for the first two weeks onboard MIR. After this initial period of adaptation, performance in all tasks and all subjective workload ratings returned to pre-flight baseline level and remained fairly stable for the following weeks in space.