A key problem in Project Mercury, possibly one of the most demanding and challenging, was the development of a life support system which would operate without fail under the conditions of orbital space flight. The technology to develop such a system was at hand, as demonstrated in the successful balloon flight of an Air Force flight surgeon, David G. Simons, in 1957, which attained an altitude record of 30,942 meters and lasted for 32 hours. Translating this technology into a spacecraft system, however, was a difficult undertaking for engineers and biomedical scientists. The human requirements for protection, proper breathing atmosphere, maintenance of pressure, provision of food and water, removal of metabolic by-products, and thermal control had to be matched with severe constraints concerning reliability, size, weight, power demands, and operation under conditions of thermal extremes, acceleration, and weightlessness. The system as finally designed functioned perfectly.Project Mercury, designed specifically to prove man's ability to survive in the space environment, lasted from May 1961 to May 1963. There were two sub-orbital flights and four orbital missions, including one which lasted for 34 hours and made 22 orbits of the Earth.
Voskhod ProgramThe second-generation spacecraft, Voskhod, differed from the Vostok craft primarily in the removal of the ejection seat to afford room for a three-man crew. Due to the success of the previous series, the crew now wore coveralls rather than the cumbersome pressurized suits. With the crew of Voskhod 1 including a military physiologist and a civilian technical scientist in addition to the commander, more comprehensive medical data were obtained on that flight. The detailed onboard physiological measurements were combined with extensive biotelemetry to evaluate future telemetry needs. In addition to the now-standard biomedical parameters monitored on Vostok, Voskhod also included onboard studies of hearing, lung function, the state of the vestibular apparatus, and muscle strength during weightlessness.The second (and last) flight of Voskhod was remarkable for a 20-minute EVA conducted by one crewman, wearing a self-contained life support system. Due to a failure of the automatic reentry Launch Date