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HISTORICAL PERSPECTIVE

a human being. Alexei Leonov in one of the documen- taries describes how Korolev met with the cosmonauts in training and chose Gagarin (Fig. 8) apparently more because of his personality rather than objective data. All of the 20 or so cosmonauts in training were pilots of fighter aircraft, as was the case with the 7 astronauts who made up the U.S. Mercury team.

Yuri Alekseyevich Gagarin (1934–1968) was launched into low Earth orbit by means of an R-7 booster on April 12, 1961. According to the documentaries, some people in the launch team had serious misgivings about the proposed flight because there had been a number of rocket failures. For example, there was an explosion of a ballistic missile at the launch site only 6

mo before that killed

165 people, including

of leaders in the space flight, much thought had

program. Before been given to the

a number Gagarin’s effects of

spaceflight on the human body and extensive research on the effects of weightlessness on various animals had been carried out by the Institute for Biomedical Prob- lems in Moscow under the directorship of Oleg Geor- gievich Gazenko (1918–) using free-fall from high-alti- tude balloons. This institute was responsible for various aspects of human environmental physiology, including space, high altitude, and diving (2). In fact, there was some crossover between these disciplines in part because of the Russian belief in cross-adaptation. The thrust of this was that adaptation to one environ- mental extreme improved the ability of the body to withstand another environmental stress. For example, it was believed that acclimatization to high altitude improved human tolerance to very high accelerations. The Soviets were just as macho as anybody else in this area; in one of the television documentaries, Alexei Leonov proudly states that he has tolerated 14 G. Of course Gagarin’s flight produced a sensation through- out the world, but many of the details were unknown until recently. As an example, it was assumed for a long time that Gagarin had landed in his space cap- sule, and one of the television documentaries implies this. However, it is now known that Gagarin ejected

from the spacecraft at an altitude of came down by parachute.

7,000 m and

Excerpts from Gagarin’s personal account of his flight are now available (Ref. 5, p. 170–175), and they make fascinating reading. The acceleration during the launch exceeded 5 Gx (eyeballs in) but did not prevent Gagarin from communicating with the ground. Once in orbit he described the appearance of the Earth and the unexpected complete blackness of the sky as has now been done many times since. He had no problem with eating or drinking. During the flight (duration of 1 h and 48 min), a number of physiological variables were monitored, including electrocardiogram and chest movements by pneumography. A television camera also recorded the cosmonaut’s activities.

Fig. 8. Yuri Alekseyevich Gagarin (1934–1968), who was the first human being to enter space.

The main physiological variables that were moni- tored were the electrocardiogram and respiration rate (18). Four hours before launch, the heart rate was 65 beats/min and the respiration rate was 12 breaths/min. Interestingly, 5 min before launch, the heart rate had risen to 108 beats/min and the respi- ration rate to 25 breaths/min, presumably because of anxiety. One minute after the start of the launch, the heart rate exceeded 150 beats/min. At this time, Gagarin was exposed to increased acceleration forces, vibration, and noise from the rocket engines, but he reported that these sensations were easily tolerated. As the spacecraft ascended and then en- tered orbit, the heart rate steadily fell to about 100 beats/min. After 20 min of weightlessness, the rate had fallen slightly farther with a mean of 97 and range of 85–113 beats/min. However, the respiration rate tended to remain high so that during the period of 10–15 min after the beginning of weightlessness it ranged between 24 and 37 breaths/min. During de- scent after the braking rockets were fired, the pulse

J Appl Physiol VOL 91 OCTOBER 2001 www.jap.org

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