Thermal Comfort Under Weightlessness Exposure: A Discriminant Analysis

Astronauts under weightlessness or microgravity would have differences in thermal comfort due to several adaptive physiological changes caused by the absence of the gravity. In this study, the Mahalanobis distance discriminant was conducted to investigate the classifications of the mean thermal comfort votes (MTCV) in weightlessness, in terms of the ratio of low-frequency power (LF) and high-frequency power (HF) of the heart rate variability (HRV). The ratio was abbreviated as LF/HF and it represented the balance of the autonomous nervous system and acted as an indicator of the thermal comfort. This study was based on our previous research data that had been acquired from 6 male participants under simulated weightlessness through heard-down bed rest (HDBR) model. Results showed that when LF/HF