Bioinstrumentation for evaluation of workload in payload specialists: results of ASSESS II

ASSESS II (Airborne Science/Spacelab Experiments System Simulation) was a cooperative NASA-ESA project which consisted of a detailed simulation of Spacelab operations using the NASA Ames Research Center CV-990 aircraft laboratory. The Medical Experiment reported on in this paper was part of the complex payload consisting of 11 different experiments. Its general purpose was to develop a technology, possibly flown on board of Spacelab, and enabling the assessment of workload through evaluating changes of circadian rhythmicity, sleep disturbances and episodical or cumulative stress. As parameters the following variables were measured: Rectal temperature, ECG, sleep-EEG and -EOG, the urinary excretion of hormones and electrolytes. The results revealed evidence that a Spacelab environment, as simulated in ASSESS II, will lead to internal dissociation of circadian rhythms, to sleep disturbances and to highly stressful working conditions. Altogether these effects will impose considerable workload upon Payload Specialists. It is suggested that an intensive pre-mission system simulation will reduce these impairments to a reasonable degree. The bioinstrumentation applied in this experiment proved to be a practical and reliable tool in assessing the objectives of the study.