Mercury Medical Operations

AS HAS BEEN NOTED, on November 29, 1961, while Enos orbited the earth, Project Mercury officials had announced that John H. Glenn would be the prime astronaut for the first manned orbital mission with M. Scott Carpenter as backup, and that Donald Slayton would be the prime astronaut for the second manned orbital mission with Walter Schirra as backup.[1]

Through the next weeks the tension once more built up at Cape Canaveral as the pattern of the Shepard and Grissom flights was repeated on an even more intense scale. Perhaps no part of history has been better documented than the U.S. orbital flights. To recount again the emotional drama that accompanied them—particularly the first U.S. orbital flight—would be anticlimactic. Yet each, in its own fashion, led man progressively further toward his goal of space exploration.

At Cape Canaveral, countdown for Marine officer Glenn began again and again, only to be postponed for first one reason and then another. Disciplined patience now became the supreme virtue as the astronaut’s will was tested no less than that of the Nation. The fruits of technology were not perfect and there were to be malfunctions; the weather yielded itself to no man’s convenience. Astronaut Glenn waited . . .(See picture of Glenn's preparation)

On February 20, 1962, after eight postponements, he was finally launched and successfully completed three orbits of the earth in his spacecraft Friendship 7. This flight was followed on May 24, 1962, by the MA-7 flight, M. Scott Carpenter’s three-orbit flight in the Aurora 7 spacecraft. Originally it had been planned that this flight would be made by "Deke" Slayton, whose grounding for medical reasons in March 1962 is discussed in the next section. Walter M. Schirra made a six-orbit flight in the Sigma 7 spacecraft (designated the MA-8 flight) on October 3, 1962. On May 15, 1963, Gordon M. Cooper flew the final Mercury orbital mission in the Faith 7 (MA-9 flight), bringing to a close the first phase of the United States’ manned space flight effort.[2] (See picture of other Mercury flights)

Although it had been announced on November 29, 1961, that Donald Slayton would be the prime astronaut for the second U.S. manned orbital mission, on March 16, 1962, NASA announced that he would be replaced by M. Scott Carpenter, alternate pilot in the Glenn mission. This decision, made at NASA Headquarters, was prompted by a minor heart defect, on record since 1959. The physical disability which caused Astronaut Slayton’s disqualification was described as "recurring arterial fibrillation without heart disease." Little positive information was available concerning either the etiology or prognosis of this condition. Since the medical profession did not establish a firm prognosis in this case, the decision whether Slayton would fly the mission was one that had to be made by management.

This decision by NASA was to be discussed extensively by the press following a news conference held by NASA at noon that day, with Dr. Hugh Dryden, Deputy Director, NASA; Dr. Roadman, Director, Aerospace Medicine; Astronaut Donald K. Slayton; and John H. (Shorty) Powers, Public Affairs Officer, participating.[3] For example, in an interpretive report, William Hines of the Washington Sunday Star wrote:

The decision to ground the astronaut had been made by NASA Headquarters, and not by Dr. Robert R. Gilruth, Director of the Manned Spacecraft Center (formerly the Space Task Group), who had said:

Nevertheless—bowing to medical advice—the management echelon at NASA Headquarters decided that Astronaut Slayton would not undertake the MA-7 mission. Whether he would be given a clean bill of health to fly in future missions remained to be determined. Dr. Dryden had stated in the March 16 press conference that Slayton would remain in the Mercury program and might possibly yet make a flight.

Following extensive observation and examination by eminent specialists, including Dr. Paul Dudley White (who had attended former President Eisenhower), it was recommended by the Director of Space Medicine, Office of Manned Space Flight, that Astronaut Slayton be removed from consideration "for any Mercury flights."[5] On July 11, NASA reported:

Astronaut Slayton would, however, remain with the manned Spacecraft Center, assuming new engineering and operational planning duties on all manned space flight programs, including Projects Mercury, Gemini, and Apollo.

Except for this one incident, the six orbital flights of Project Mercury were to proceed as planned. Modifications in life-support systems were continuous as increasing experience was gained. Also, as the missions progressed, the initial elaborate medical procedures for tracking and recovery operations were modified. Increasingly, NASA turned to its own growing medical in-house capability and became less dependent upon the Services for medical support.

The author remembers vividly the contrast between the first suborbital flight, viewed on television from the conference room of the USAF Surgeon General in Washington, D.C., on May 5, 1961, and the 22-orbit flight of Astronaut Cooper, last of the Mercury flights, which was viewed from the blockhouse at Cape Canaveral on May 15, 1963.

In 1961, the U.S. capability was untried. Now, in 1963, there was confidence born of experience. The author recalls the predawn trip from Patrick Air Force Base to the Cape on May 14, 1963, and the long wait atop the blockhouse as events on the gantry seemed slowly to take shape. Through binoculars the orange-red gantry could be viewed at close range; and with the naked eye it could be seen in the distance as the sun rose. Nearby, the noisy helicopters waited and the scuba divers in their black leotards and fin shoes lounged in readiness. The sounds of the loudspeaker system battled with those of transistor radios carried by various individuals.

That morning there appeared to be trouble with the gantry, and as the visitors stared at the spacecraft poised on the launch vehicle that spewed a continuous white steam from the area near the ground, there was intermittent conversation ...

"Do you remember," one medical officer asked another, "how one of the astronauts found it imperative to void in his pressure suit prior to count-down?"

"And do you remember," asked someone else, "the ham sandwich that was smuggled aboard a previous flight?"

Apocryphal or not, these were reminders that it was man—a normal, functioning man, constrained in his activities by biological considerations that science and technology could not change—who was being launched into orbit.

Suddenly, then, the word "Scrub!" The flight was postponed.

Next day the observers waited as they had waited the previous day; the countdown finally ticked away; the big Atlas slowly rose off the pad, gaining speed, turned in the direction of the blockhouse, and soared out of sight. Through the long day, the author, like the world, waited and watched by television the progress of Astronaut Cooper. At one point, General Roadman took her, along with other NASA Headquarters Space Medicine observers, to the Mercury Control Room. Sitting silently, watching, were Dr. Gilruth and D. Brainerd Holmes. Behind them were the group of new astronauts, chosen to supplement the original seven. In the center of the room sat Lt. Col. Charles Berry, USAF (MC) (who had succeeded Dr. Stanley White), at one of the control positions. At this point in the mission it might be a medical decision as to whether, at any time, the flight would be cut short.[7]

This flight, successfully concluded after 22 orbits, brought Project Mercury to a close.

The Mercury staff in October 1963 briefed the scientific community on its evaluation of the Mercury Program.[8] Aeromedical considerations were discussed in detail by the staff of the Manned Spacecraft Center, and will be only briefly summarized here. Medical Operations involved medical maintenance and preflight preparation, medical monitoring, analysis, physiological responses to space flight, and recovery operations.

Medical maintenance for the astronauts had included routine medical care, together with annual and special physical examinations. Preflight physical examinations were given for two purposes: To allow the flight surgeon to state that the astronaut was qualified and ready for flight; and to provide a baseline for any changes resulting from exposure to the space-flight environment. Early in the program, 10 days before the scheduled mission, the flight astronaut and his backup were given a thorough evaluation. This was performed by a Department of Defense team of medical specialists providing the specialties of internal medicine, ophthalmology, neurology, psychiatry, and laboratory medicine. These specialties continued to be represented in later flights, although certain modifications were made as experience demonstrated the lack of serious effects of flight on the astronaut. Three days prior to the flight a detailed physical examination was completed by the various medical specialists with necessary laboratory work.

On the morning of the flight, a brief medical examination was made to determine the readiness of the astronaut. On the last two missions, MA-8 and MA-9, participation was reduced to that of the flight crew surgeon only.

The postflight medical examinations were made initially by Department of Defense recovery physicians stationed aboard the recovery vessel, but as the flights were lengthened and experience accumulated, the pattern here too was modified. On the early missions, the astronaut was flown to Grand Turk Island where he was joined by the team of medical specialists who had made the preflight examination and by the flight crew surgeon. In the later, longer flights, when the recovery was made in the Pacific Ocean, NASA flight surgeons were predeployed aboard the recovery carrier to per-form the initial postflight examination and debriefing.

Several valuable lessons were learned both with respect to the pattern of medical care provided and to policies relating to the astronaut. In the first instance, it was learned early that there was need for many practice runs. A medical countdown was developed with specific timing of events. Also it was learned that backup personnel were needed, just as backups were needed for the various pieces of equipment, although the number must be kept at a minimum.

With reference to the individual astronaut, the medical profession learned many lessons from the flights. For example, initially consideration had been given to isolating the flight crew so as to prevent development of a communicable disease immediately prior to flight. This soon proved impractical, however, because the astronaut had too many last-minute activities. Because of the relatively short period of the Mercury flight, no difficulty was experienced with a very modified isolation plan, although it was recognized that longer periods of flight in future missions might call for an evaluation of this problem.

Initially the basic concept regarding drugs had been that they would be made available for emergency use only. Injectors made it possible for the astronaut to self-administer drugs through the pressure suit. (see picture of automatic medical injectors) For the first four missions these drugs included ananodyne, an anti-motion-sickness drug, a stimulant, and a vasoconstrictor for treatment of shock. In later missions these were reduced to the anti-motion-sickness drug and an anodyne (available both in the suit and in the survival kit). For the last Mercury flight (MA-9), it was decided to make tablets of dextro-amphetamine sulfate available, both in the suit and in the survival kit, and medication was used for the first time during flight when the dextro-amphetamine sulfate was taken prior to the initiation of retrosequence.

Experience showed that care must be taken to prevent astronaut fatigue during the final preflight preparations as well as during postflight activities. Minimum time for postflight rest and relaxation following a 34-hour mission was between 48 and 72 hours.

Dietary control was in force for approximately 1 week prior to each mission. To prevent defecation during the mission, a low-residue diet was programmed for 3 days prior to launch, with the time extended if the launch was delayed.

In flight, food consisted of bite-size and semi-liquid tube food on early missions, although on the MA-9 mission freeze-dehydrated food was added. The bite-size food caused problems by crumbling and some difficulty was encountered in hydrating the freeze-dehydrated food.(See picture of Mercury food).

In the early missions urine was collected in a single container within the suit, but this device became unworkable as the mission time increased. Modifications of the suit made it possible to collect five separate and complete samples, although the system would require modification for future missions.

No blood samples were obtained during flight, and every attempt was made to combine the various blood requirements so as to minimize the number of venipunctures, both preflight and postflight.

When the Mercury program began, continuous monitoring of physiological data while a pilot performed his flight mission was a new concept. Consequently, there were no off-the-shelf items for continuous and reliable monitoring. When it was decided to attempt to monitor body temperature, chest movement, and heart action (ECG), equipment standards were established: The sensors and equipment must be comfortable, reliable, and compatible with other spacecraft systems, and must not interfere with the pilot’s primary mission. Biomedical sensors were used primarily to assist the flight surgeon in determining whether the astronaut was physiologically capable of continuing the mission.(See picture of biosensors attached to astronauts)

Considerable experience was gained through the use of range simulations as well as actual flight. It was soon apparent that the medical flight controller was an extremely important member of the flight control team. The development of mission rules to aid in flight control was necessary in the medical area as well as in the many engineering areas. As experience was gained, the evaluation and judgment of the medical flight controller were the prime determinants in making a decision. According to Dr. Berry, the "condition of the astronaut as determined by voice and interrogation rather than physical parameters alone became a key factor in the aeromedical advice to continue or terminate the mission."[9]

The physiological parameters monitored were modified as experience was gained. Body temperature was monitored with a rectal thermistor in all missions. The thermistor would be modified for oral use in future missions of longer duration. Respiration was measured initially by an indirect method through the use of a linear potentiometer and carbon-impregnated rubber. Soon this method was replaced by a thermistor kept at 200 degree F and placed on the microphone pedestal of the helmet. Since neither gave reliable respiration traces, a change was made to the impedance pneumograph for the MA-8 and MA-9 flights. This device provided accurate respiration information during most of the flight.

Electrocardiographic electrodes of a low impedance to match the spacecraft amplifier were required to record during body movements and to stay effective during flight durations of over 30 hours. These electrodes, Dr. Berry notes, functioned well and provided excellent information on cardiac rate and rhythm.

Not until the MA-6 mission of Astronaut Glenn had blood pressure readings been taken, because until that time no satisfactory system had been developed. As early as the MR-3 flight, however, definitive work had begun with an automatic system using a unidirectional microphone and cuff. The system without the automatic feature was used on the MA-6 mission. During MA-7, all the inflight blood pressure readings obtained were elevated. An extensive postflight evaluation determined that instrument error had probably caused this result. Suggested remedies included considerable preflight calibration and matching of the settings to the individual astronaut along with the cuff and microphone. Excellent blood pressure tracings were obtained in both the MA-8 and MA-9 flights.

Voice transmissions were a valuable source, and the normal flight re-ports and answers to queries were used for evaluation of the pilot. (To insure that the medical monitors were familiar with the astronaut’s voice, tapes of mission simulations were dispatched to all range stations.)

Inflight photography and television proved of little value in medical monitoring because of the poor positioning of the cameras and the varying lighting conditions that resulted from the operational situation.

One of the basic objectives of Project Mercury was to evaluate man’s responses to the space-flight environment. The stresses of this environment which would elicit physiological responses included, according to Dr. Berry,[10] the wearing of the full-pressure suit although not pressurized in flight, confinement and restraint in the Mercury spacecraft with the legs at 90 degree elevated position, the 100 percent oxygen atmosphere at 5 psi pressure, the changing cabin pressure through powered flight and reentry, variation in cabin and suit temperature, the acceleration forces of launch and reentry, varying periods of weightless flight, vibration, dehydration, the performance required by the flight plan, the need for sleep and for alertness, changes in illumination inside the spacecraft, and diminished food intake.

Data showed that the peak physiological responses were closely related to critical inflight events. The six astronauts who flew a mission showed themselves capable of normal physiological function and performance during the accelerations of launch and reentry; they tolerated the vibration of launch and reentry well; there was no evidence of motion sickness. The heat loads imposed caused discomfort upon occasion but did not become a limiting factor in the missions.

Since the Mercury missions were planned for altitudes that would not involve contact with the Van Allen radiation belt, radiation was not considered to be a problem until the manmade radiation belt was noted prior to the MA-8 mission. At that time, personal dosimeters were added within the astronaut’s suit and inside the spacecraft. The MA-8 and MA-9 flights revealed that the astronauts received no greater radiation dose than would have been received on earth, and even less than that received during a chest X-ray.

Weightlessness caused no problems, according to the astronauts. They were able to conduct complex visual-motor coordination tasks proficiently in the weightless state. No evidence of body system dysfunction was discovered during the flights. Urination occurred normally in time and amount, and there was no evidence of difficulty in intestinal absorption in the weightless state.

Signs of orthostatic hypotension were noted after the last two missions; they persisted for between 7 and 19 hours after landing.

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 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 graphical treatment. These included subjecting the data to computers using techniques such as chi-square, correlation, analysis of variance, and factor analysis, and utilizing the data in the construction of graphs such as figure 3 and figure 4.

Preflight and Postflight Data

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-4, 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 a comparison of typical preflight and postflight urine values (table XI).[15] 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 by 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.

Two basic requirements for the medical support of Project Mercury recovery operations were the provision of prompt, optimum medical care for the astronaut if necessary upon his retrieval from the spacecraft and the early medical evaluation of the astronaut’s postflight condition. Experience led to a change in emphasis from taking the medical care to the astronaut, as practiced in the early missions, to returning the astronaut to a point where he could receive this care, as provided in later missions.

In the launch-site area, medical support included a general surgeon, an anesthesiologist, a surgical technician and nurses, a thoracic surgeon, an orthopedic surgeon, a neurosurgeon, an internist, a pathologist, a urologist, a plastic surgeon, and supporting technicians. In early missions they were deployed to Cape Canaveral. On the last two missions it became necessary, because of the distances involved, to develop a team at Tripler Army Hospital, Hawaii, for the Pacific area in addition to the team at Cape Canaveral which covered the Atlantic area. Because such large numbers of highly trained physicians were thus deployed without the likelihood that their services would be required, it was concluded, after careful evaluation, that the specialty team could be maintained on a standby basis at a stateside hospital and flown to Cape Canaveral or a recovery site if their services were needed. Surgical resuscitation teams would be available at these sites, and other launch-site support would be provided by a point team composed of a flight surgeon and scuba-equipped pararescue personnel airborne in a helicopter. Medical technicians who could render first aid were also available in small vehicles on the Banana River at Cape Canaveral. A surgeon and an anesthesiologist, together with supporting personnel, were stationed in the blockhouse at Cape Canaveral to serve as the first echelon of resuscitative medical care in the event of an emergency. This was in accordance with basic planning discussed earlier in this study.

For the early missions each vessel was assigned a surgeon, an anesthesiologist, and a medical technician team with the supporting equipment necessary for evaluation and medical care. Later, this distribution was modified to include the assignment of a single physician (either a surgeon or an anesthesiologist) to the destroyer. The general concept was that he would provide resuscitative care only, and then evacuate the astronaut to the carrier in his particular area.

Project Mercury had demonstrated forcibly that man could survive and function ably as a pilot-engineer-experimenter in the space environment without undesirable reactions or detriment to normal body functions for periods of as long as 34 hours. Other medical knowledge gained included the fact that there had been no evidence of abnormal sensory, psychiatric, or psychological response to an orbital space flight of up to 1 Omega days. Sleep in flight was proved to be possible and subjectively normal. The radiation dose received by the astronauts was considered medically insignificant.

Following missions of 9 and 34 hours’ duration, there was an orthostatic rise in heart rate and fall in blood pressure, which persisted for between 7 and 19 hours after landing. The changes following the 34-hour flight were of greater magnitude than those following the 9-hour flight, but all changes disappeared in a similar time interval in both cases. The implications of this hemodynamic response obviously would require serious study prior to longer space missions. No other clearly significant changes were found in the comprehensive preflight and postflight physiological examination.

Certain basic problems in space medicine remained unresolved, although investigators were now in a much better position to utilize improved biomedical instrumentation and to establish experimental designs having greater potential for solving these problems. What would be the effects of prolonged weightlessness and combined stresses upon the astronaut? What would be the effects of space radiation? Would toxic hazards within the spacecraft endanger the safety of the astronaut? Some basic biological questions had to be answered. How would man survive for extended periods of time in a closed ecological system? Could his food and wastes be recycled and regenerated? Problems of biotechnology, too, were still unsolved.

All these fundamental problem areas had been defined in the late 1940’s by Strughold and his group at the School of Aviation Medicine, Texas, on the basis of the German aeromedical experience at Peenemunde, and logically on man’s historical ability to observe. In this sense, space medicine may indeed have been said to antedate aviation medicine.(See picture of first Director of Space Medicine--Dr. "Randy" Lovelace ).

Be that as it may, the problems had been defined long since. Project Mercury had provided the first step in answering them. Simulation and testing on centrifuges could provide a partial answer, but only through actual experience in orbiting space laboratories could the larger answers be provided. As Project Mercury drew to a close, the scientific community looked forward with confidence to meeting that challenge.

[1] Aeronautical and Astronautical Events of 1961, Report of the National Aeronautics and Space Administration to the Committee on Science and Astronautics, U.S. House of Representatives, 87^th Cong., 2d sess., June 7, 1962, p. 68.

[2] See: (1) Results of the First United States Manned Orbital Space Flight, February 20, 1962, Manned Spacecraft Center, NASA. (2) Results of the Second United States Manned Orbital Space Flight, May 24, 1962, NASA SP-6.

(3) Results of the Third United States Manned Orbital Space Flight, October 3, 1962, NASA SP-12, 1962. (4) Mercury Project Summary Including Results of the Fourth Manned Orbital Flight, May 15 and 16, 1963, NASA SP-45, 1963.

[3] Transcript of News Media Conference, Pilot Change in Mercury-Atlas No. 7,12:15 p.m., Friday, March 16, 1962.

[4] William Hines, "Slayton’s Grounding Raises Questions on Space Pro-gram," The Sunday Star (Washington), Mar. 18, 1962. See also NASA Press Release No. 62-67, Mar. 17, 1962.

[5] Brig. Gen. Charles H. Roadman, Director, Aerospace Medicine, Office of Manned Space Flight, Memo for D. Brainerd Holmes, Director of Manned Space Flight, July 10, 1962.

[6] NASA Release No. 62-161, July 11, 1962. Subsequently, Major Slayton resigned from the Air Force and assumed important duties with MSC in a civilian capacity.

[7] Personal notes of the author.

[8] Mercury Project Summary Including Results of the Fourth Manned Orbital Flight, May 15 and 16, 1963, NASA SP-45, 1963. This 444-page document provides the basis of the following summary which, in many instances, is a synoptic version of the original document. See particularly Charles A. Berry, ch. 11, "Aeromedical Preparations," pp. 199-209.

[9] Ibid, p.204

[10] Ibid, p. 206

[11] Jefferson F. Lindsey, "Mathematical and Statistical Designs in the NASA Space Medicine Program," Proceedings of the Second Biomathematical 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-03375, 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.

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	Curators: Afzal Ahmed  and Julie Oliveaux
	Responsible NASA Official: Judith L. Robinson, Ph.D.
	Several NASA centers participate in the Life Sciences Data Archive project: Judith L. Robinson, Ph.D., LSDA Project Manager Paul X. Callahan, Ph.D., Data Archive Project Manager at NASA Ames Research Center (ARC) Judith L. Robinson, Ph.D., Data Archive Project Manager at NASA Johnson Space Center (JSC) Bridgit O'Hara Higginbotham, Data Archive Project Manager at Kennedy Space Center (KSC)
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