The conference on aviation and space medicine, the proceedings of which are published in this collection, was held at a time of remarkable achievements by our people in their striving for the peaceful conquest of outer space. The realization of the first space flights of man testifies to the magnificent accomplishments of Soviet science and engineering.

Soviet medicine has made a significant contribution to the preparation for and successful achievement of space flights. We are referring here to space medicine, a new branch of knowledge that has evolved in recent years from aviation medicine.

The last 30 years were marked by the blossoming of Soviet aviation medicine. As long ago as 1934 at an All-Union Conference on the Stratosphere, called at the initiative of the USSR Academy of Sciences the leading scientists of our country were focusing on the medical aspects of man's mastery of the stratosphere.

A conference on aviation medicine held in 1939 in Leningrad summed up the results of the research done at that time and outlined future research. It is now clear that the scientists of that era obtained factual data and advanced theories which significantly affected the safety of flights beyond the earth's atmosphere.

During the 25 years that have elapsed since the Leningrad conference our scientists have done a tremendous amount of work to ensure the safety of flights by civilian and military aircraft and made outstanding progress in space medicine.

During the arduous years of World War II, Soviet aviation medicine not only coped with current practical problems, but was able to ensure the safety of the first flight of man in a rocket-propelled vehicle. This was made possible by the extensive investigations conducted by many teams in academic and other institutions on the effect on the human organism of the environmental factors characteristic of flight. These investigations were conducted as part of comprehensive high-altitude expeditions, on special testing equipment simulating various flight factors, and during flights themselves.

Whereas the subject matter of the 1939 conference dealt mainly with the problems involved in ensuring the safety of high-altitude and prolonged flights, a distinguishing feature of this past conference was the broad range of problems pertaining to man's survival on various vehicles traveling in the earth's atmosphere and beyond in outer space.

This conference was called because the matters discussed at the meetings and conferences systematically organized by the Division of Biological Sciences, USSR Academy of Sciences, showed that the time had come for a detailed discussion of the accumulated data, if we were to attract even more scientists into the fields of aviation and space medicine.

This conference heard reports on increasing resistance to various flight factors, with emphasis on those factors specific to space flight. It examined the effect of gravity, which includes matters relating to man's exposure to weightlessness and the influence of accelerations of different intensities and directions. It dealt with the problem of living under the conditions of extended flights on spacecraft. The conference paid considerable attention to various medical aspects of space flight, especially the main problems of flight physiology and psychology.

The papers fell into the following groups :

(a) Those dealing with the effect on the organism of various environmental factors (high barometric pressure, low partial pressure of oxygen in inhaled air, high and low temperature, different kinds of radiation, etc.).

(b) Those dealing with the effect on the organism of dynamic flight factors (acceleration, weightlessness, noise, and vibration).

(c) Those dealing with physiology and psychology, hygiene of flight activity, and problems involved in medical examination.

Acquainting large groups of physicians, biologists, and specialists in other disciplines with the proceedings of the conference will contribute to the further progress of aviation and space medicine in our country.


RESULTS OF PHYSIOLOGICAL INVESTIGATIONS ON THE SPACESHIPS VOSTOK 3 AND VOSTOK 4

One of the important objectives of the first tandem space flight of the Vostoks was to investigate the effect on the human organism of prolonged weightlessness. Thanks to the use of several new techniques and improved older ones employed during the preceding flights, it was possible to obtain a large amount of physiological information. Evaluation of this information required that it be compared with the data derived from ground tests simulating some of the conditions obtaining during space flight and with the results of some laboratory investigations.

Extensive material (obtained by telemetry, from radio conversations, logs kept on board, postflight reports and talks) was used to judge the functional state of the astronaut's central nervous system during the flight. Analysis of the material showed that prolonged weightlessness had no appreciable effect on the functional capabilities of the central nervous system of either astronaut. Their efficiency remained at a high level; they performed a variety of tasks during the flight, some involving flight duties, others for research purposes. The astronauts said they did all kinds of work easily and without fatigue during the three and four days of flight. This was objectively confirmed by psychological tests administered during flight. According to EEG data, during the first few hours of exposure to weightlessness there was a predominance of rhythms with a frequency of 5-7 oscillations per second and a comparatively high amplitude. Similar EEG changes have been noted in athletes after intense physical exertion. Later there was a gradual shift toward high-frequency oscillations (beta rhythm) with a decrease in the average amplitude of the EEG biopotentials.

Worth noting are the dynamics of electric resistance of the skin, which decreased during the first hours of flight and before landing, indicating marked emotional stress on the part of the astronauts. The daily periodicity of electric resistance of the skin increase at night and decrease during the day remained unimpaired throughout the flight. This fact tends to reflect the functional stability of the higher autonomic centers.

Electro-oculograms (EOG) were recorded during flight to evaluate the condition of the vestibular apparatus. Vestibular tests, sometimes with simultaneous recording of an EOG, were included in the program to determine any impairment of vestibular function. According to EOG data, asymmetry of oculomotor reactions, which might indicate impairment of the vestibular centers, and nystagmus were not detected in either astronaut. Analysis of the vestibular tests not accompanying the EOG recording likewise failed to reveal any significant impairment of vestibular function.

EOG investigations, besides the light they throw on the state of the vestibular centers, are of definite value in appraising the level of oculomotor activity, which to some extent may reflect the general activity and motor activity of the astronaut throughout the flight . The changes in oculomotor activity in both astronauts were phasic in character. At the beginning of the flight it was high in A. G. Nikolayev, less so in P. R. Popovich 4-6 eye movements per second.

Eye movements were sweeping and frequently uncoordinated. Motor activity diminished during the 6th and 7th orbits and now solitary, now group oscillations were recorded on the EOG. Subsequently, the EOG revealed a periodic increase or decrease in oculomotor activity. At the end of the flight, both astronauts had secondary, persistent intensified oculomotor reactions, but this activity was much less than at the be- ginning of the flight.

Cardiac activity was investigated by recording EKGs in the thoracic lead. There was a slight pulse acceleration just before the launching (Nikolayev from 98 beats/min to 112 beats/min; Popovich from 94 beats/min to 136 beats/min), with a corresponding shortening of the PQ and QT intervals). EKG changes during the active part of the flight were similar to the data obtained in the course of investigations in the centrifuge. The maximum pulse rate in the first minute of flight was 136 beats/min and 132 beats/min in Nikolayev and Popovich, respectively. After going into orbit, the pulse rate dropped to the level observed 4 hours before the launching during the 6th-7th orbits in Nikolayev and during the 3rd-4th orbits in Popovich. It will be noted that in the course of training in the centrifuge, the pulse rate returned to normal in 5-10 minutes. No EKG changes were noted that might indicate impairment of automatism, excitability, or conductivity. However, 3 single extrasystoles were recorded in Popovich during flight; these also occurred in the course of various tests and training. The nature of the daily periodicity of cardiac activity did not change during flight .

According to pneumographic data, there were no respiratory abnormalities. During the active part of the flight there was some acceleration of respiration, which matched the data obtained during tests in the centrifuge.

Thus, no pathological changes were noted in the physiological functions of either astronaut throughout the flight.

In the active part of the flight there were functional changes that matched the data obtained during tests in the centrifuge. The first few hours of orbital flight were marked by some changes in the functional state of various systems, as shown by a slow return to normal of the pulse, nature of the EEG changes, and electric resistance of the skin.

The nature of the EEG changed in the course of prolonged (3-4- days) exposure to weightlessness, as shown by changes in the relationship between the processes of excitation and inhibition in the higher divisions of the CNS. At the same time, the mental activity and neuroregulatory capabilities of the astronauts remained on a high level.