The foregoing conclusions are based on the extensive data that were collected, reduced, and analyzed in connection with Project Mercury. Many of the scientific papers on various phases of the program are cited throughout this monograph. There is sufficient agreement among reputable investigators to validate the general conclusions drawn. It will not, therefore, be the purpose here to set forth statistical and mathematical treatments of the data, but rather to present representative types of medical data acquired. This is done without analytic comment to provide a historical record and to serve as a possible reference source for scientific investigators.
Two representative types of medical data will be presented: (1) Those medical data acquired in-flight during the six manned space missions of Project Mercury, and (2) the medical data primarily acquired immediately before and after each of the six missions.
In-flight data were acquired and analyzed primarily to determine the well-being of the astronaut while in flight, and to make postflight detailed analyses of medical aspects of each mission for analytic, comparative, and predictive purposes.11 The physicians monitoring the well-being of each astronaut while in flight used data which were telemetered to the ground stations for immediate assessments, whereas the postflight analyses were conducted after the completion of the missions, essentially from records which had been made on board the spacecraft during flight.
Several kinds of data were acquired, including physiological, environmental, and operational performance data. The physiological data included electrocardiogram (ECG), respiration, blood pressure, and body temperature. Spacecraft environmental data consisted of acceleration, space-suit inlet temperature, suit outlet temperature, carbon dioxide partial pressure, and cabin pressure. The operational performance type of data included a continuous record of what each astronaut was doing (performing) and what he was saying throughout each mission.
The postflight analysis of in-flight medical data focused attention upon time-line analysis information. That is, the data were prepared in such a manner that the physician could analyze and assess, within the limits of the measurements taken, the composite of what was occurring to the astronaut at any given time interval, and for consecutive time intervals. For example all relevant information for a given time interval was recorded on one data sheet. This included available information of importance to the physician concerning the physiological, environmental, and operational performance measurements for a specific time interval of short duration. Next, additional data sheets were constructed for consecutive time intervals. If the first data sheet covered the 10-second interval immediately after liftoff, the succeeding data sheet would cover the interval from 10 seconds to 20 seconds, and the next sheet, 20 seconds to 30 seconds, and so on.
The requirements for the duration of time intervals were different for various portions of a mission. This was because the physician is interested not only in change, per se, but also in the rate of change, and the rate-of-rate of change, of physiological reactions and environmental conditions. These types of changes generally take place more rapidly during exit and reentry than during routine portions of a mission such as during weightlessness. A data sheet covering the short interval of 10 seconds during exit and reentry was therefore considered necessary, whereas a data sheet covering the longer interval of 1 minute during weightlessness was considered to be acceptable. Also, the 1-minute interval proved to be satisfactory in most cases for data sheets covering the preflight and postflight periods. An example of the information that was included on a data sheet is shown in figure 1.
Although the example shown is for a 10-second interval for a given mission, the data sheet for a 1-minute interval would be similar. The graphs represent the wave trains for ECG, respiration, acceleration, and voice. With reference to the ECG wave train, should there be, for example, 19 heartbeats indicated for the 10-second period, there would be 19 entries in the heart rate column. If the heart rate was not uniform, this would be evident in the entries in the heart rate column. For the data entered under each heading across the top of the data sheet, the mean and the variance for the 10-second interval were computed. Also, for the data under the headings "Heart rate," "Respiration," and "Acceleration," the standard scores were computed for each entry, converting to a mean of 50 and a standard deviation of 10 to avoid the use of negative numbers. The fact that rate is seldom identical for any given 10-second or 1-minute time interval was a major consideration here, and the resultant means, variances, and standard scores shown on each data sheet provided one important basis for interpreting the physiological and environmental changes that took place.
Considering the data sheet as a whole and its purpose, it is easy to discern why the various headings and data were selected for inclusion. It was necessary, for example, to know what activity was planned for any given time and what task the astronaut was actually performing, so that an assessment could be made of the difficulty of the tasks being performed. Was the astronaut ahead of or behind schedule? What was the relationship between activity, and physiological measurements? It was necessary to know what the astronaut was saying, how he was saying it, and how quickly he responded to questions, because certain types of analyses can be made from this aspect to assess the state of tension existing in the astronaut and possible ramifications. This information, in turn, would provide data for analysis from the standpoint of speech processes, audiology, and information processing for the crew.12
The wave train graphs served two purposes. First, they were used to check the validity of the digital entries on each data sheet to determine whether these entries were correct. This was necessary because, when converting analog data to digital form, it is likely that, some errors will be made. Such erroneous data are not used in the analyses. With respect to the second purpose, the wave form graphs were required for making pattern and wave form analyses, employing such techniques as cross-spectral analysis, autocorrelation, and Fourier analysis. Additionally, certain of the astronauts attempted to enhance their ability to withstand acceleration forces by controlling their breathing. Consequently, an analysis of the respiration wave forms could have applications to the training program, by deriving information as to the best method of breathing.
The Mercury biomedical data requirements in figure 2 indicate how consecutive data sheets of the type described were selected. The vertical column at the left represents the two suborbital Mercury missions of Alan B. Shepard, Jr., and Virgil I. Grissom (MR-3 and MR-4) and the four orbital missions of John H. Glenn, Jr., M. Scott Carpenter, Walter M. Schirra, Jr., and L. Gordon Cooper, Jr. (MA-6, 7, 8, and 9). As indicated by the row of headings across the top, there, was selected first a 15-minute period of 1-minute data sheets for a common time between T minus 60 and T minus 45; that is, there was a data sheet for T minus 60 to T minus 59, for T minus 59 to T minus 58, and progressively to T minus 46 to T minus 45.
Since physiological changes generally take place more rapidly immediately before liftoff, a sample of data sheets of 10-second duration each was selected for the period T minus 2 minutes to liftoff. Accordingly, there were 12 data sheets of this kind, since there are 120 seconds during this period, with one data sheet for each 10-second interval. The next sample selected (as shown in fig. 2) covered the period from liftoff to zero-g at 10-second intervals. This was followed by a 15-minute sample for the period from zero-g to 15 minutes past zero-g; next from zero-g plus 30 minus minutes to zero-g plus 45 minutes; and so on to the last entry, which covers the period from landing or "splash" to 5 minutes after landing.
By preparing the in-flight medical data in the time-line format described, it was possible to subject these data to many types of mathematical, statistical, and graphica1 treatment. These included subjecting the data to computers using techniques such as since chi-square, correlation, analysis of variance, and factor analysis, and utilizing the data in the construction of graphs such as figures 3 and 4.
A considerable amount of the medical data which were systematically acquired before and soon after each Mercury flight was consolidated as exemplified in tables I to XII. These tables were taken from the series of six NASA publications summarizing the results of the Mercury mission.13 Since these, publications contain more detailed information than the present discussion, they provide an excellent source of research information concerning preflight and postflight medical data. The examinations were designed to meet what would be considered requirements by a physician for the evaluation of a patient under normal clinical medical conditions.
At least one table has been selected from each of the six cited publications to provide an overview of the types of data which were acquired. The tables selected are described briefly below:
MR-3, First Manned Suborbital Flight.-Table I provides a summary
of vital-signs data, including such measurements as preflight and postflight
body weight, temperature, pulse rate, and blood pressure. In table
II a. serum and plasma enzymes summary is presented, comparing analyses
accomplished during the centrifuge program with preflight and postflight
analyses. Determinations included transaminases, esterase, peptidase,
aldolase, isomerase, and dehydrogenases.
MR-4, Second Manned Suborbital Flight.-A comparison of physical examination findings during simulated and actual flight is shown in table III. Blood chemistry findings, comparing data acquired during the centrifuge program with preflight and postflight data, are given in table IV. The blood chemistry determinations include sodium (serum), potassium (serum), chloride, protein, albumin, globulin, glucose, epinephrine, and norepinephrine.
MA-6, First Manned Orbital Flight.-The tables selected here pertain to clinical evaluation conducted immediately before and soon after the MA-6 mission.14 Evaluations were made of such factors as general status, weight, temperature, respiration, pulse rate, blood pressure, heart, lungs, and skin (table V). Fluid intake and output are shown in table VI.
MA-7, Second Manned Orbital Flight.-A preflight and postflight peripheral blood value summary was selected for illustrative purposes pertaining to this mission. This involved determinations of preflight and postflight hemoglobin, hematocrit, white blood cells, red blood cells, and differential blood count (table VII).
MA-8, Third Manned Orbital Flight.-A summary of heart rate and respiration data from physiological monitoring is presented in table VIII and a summary of blood pressure data is presented in table IX. In addition to preflight and postflight data, some in-flight determinations are given.
MA-9, Fourth Manned Orbital Flight.-The tables selected for presentation
here include one concerning pilot preflight activities (table X) and one
showing it comparison of typical preflight and postflight urine values
In addition, the data collected during tilt table studies are summarized
in table XII.
The general conclusions previously drawn about the physiological effects of space flight on man during the Mercury flights appear to be valid, as supported analyses of a considerable amount, of preflight, in-flight, and postflight medical data. Not all of these data have been analyzed with respect to each possibility that may present itself in the future. The data are available, however, for utilization in connection with additional statistical or experimental studies which may become necessary as man pursues his missions in outer space.
11. Jefferson F. Lindsey. "Mathematical and Statistical Designs in the NASA Space Medicine Program." Proceedings of the second Biomathetical Symposium, May 13-15, 1964. Graduate School of Biomedical Sciences, The Univ. of Texas, Houston, Tex.
12. John A. Starkweather. "Variations in Vocal Behavior," in Vocal Behavior Research - A Progress Report of USPHS Grant MH - 93375, Apr. 1964.
13. See Note 2. Also: Proceedings of a Conference on Results of the First U. S. Manned Suborbital Space Flight, NASA, June 6, 1961; Results of the Second U. S. Manned Suborbital Space Flight, July 21, 1961, Manned Spacecraft Center, NASA.
14. Howard A. Minners, William K. Douglas, Edward C. Knoblock, Ashton Graybiel, and Willard R. Hawkins, "Aeromedical Preparation and Results of Postflight Medical Examinations," ch. 8 in Results of the First United States Manned Orbital Space Flight, February 20, 1962, Manned Spacecraft Center, NASA.
15 A. D. Catterson, E. P. McCutcheon, H. A. Minners, and R. A. Pollard, "Aeromedical Observations," ch. 18 of Mercury Project Summary Including Results of the Fourth Manned Orbital Flight, May 15 and 16, 1963, NASA SP-45, 1963. See also "Review of Project Mercury, First U.S. Manned Space Flight Program," in National Academy of Sciences I G. Bulletin, Feb. 1964, p. 19.