Effects of Reduced Gravity

Abstract

The acceleration due to Earth’s gravity is called a 1 g environment. Humans are well adapted to living in 1 g since, through observations and experiences, they have developed an innate intuition of how the natural world behaves. For example, it is known that liquids will settle to the bottom of their containers, that objects thrown will follow a parabolic path as they fall toward the ground, and that the flame of a birthday candle will burn with familiar color and shape. However, the near-weightless environment can affect both physical and life processes and cause them to behave in seemingly counterintuitive fashions. This chapter focuses on near weightlessness and its effect on the behavior of several physical and life processes that are important to life support systems in spacecraft and habitats. Physical processes that will be discussed include fluid configurations, thermodynamic stability, aggregation, surface tension, and thermocapillary flow. Life sciences discussions will include human physiology, locomotion and perception, and plant biology.