ABSTRACT
The field of space medicine practically began before the launch of Russian cosmonaut Yuri Gagarin into orbit in April of 1961. Aviation was progressing rapidly in the few decades prior to this, and space physiology and medicine represent a natural evolution from this world. Higher altitudes and the increasing acceleration loads of high-performance aircraft required a concerted effort to understand the effects on the human occupant and provide protection to optimize performance. High-altitude balloon flights had already demonstrated the efficacy of completely enclosed cabins in rarefied atmospheres, and most of the acceleration forces and tolerances that might be encountered during launch and landing were understood from ground studies and aviation. What had to await this first launch was the understanding of the profound effects of weightlessness on the human body.
