A review of the detailed medical examinations accomplished on two astronauts who each experienced approximately 4 1/2 hours of weightless space flight reveals neither physical nor biochemical evidence of any detrimental effect. Such flights appear to be no more physiologically demanding than other nonspace-oriented test flights. Specifically, no pulmonary atelectasis has been found, no cosmic-my damage has occurred, and no psychiatric abnormalities have been produced. In spite of directed efforts to stimulate the pilot's orientation and balancing mechanisms during weightless flight, no abnormal vestibular nor related gastrointestinal symptoms have occurred. Postflight special labyrinthine tests have confirmed an unchanged integrity of the pilots' vestibular system. Although events occurring during the MA-7 mission permitted only a qualitative verification of gastrointestinal absorption of xylose, such absorption was normal during MA-6. Biochemical analyses after Astronaut M. Scott Carpenter's flight confirmed the occurrence of a moderate diuresis.

Water survival is an emergent situation requiring the optimum in crew training and procedure discipline. Furthermore, if heat stress continues to be a part of space flight, adequate fluid intake during the mission is necessary for crew performance and safety.

The experience gained in the MA-6 flight altered the medical planning for the MA-7 flight in two important respects. A comprehensive medical evaluation of the astronaut was conducted at the earliest opportunity after landing when his impressions were freshest and any acute medical alterations would have been greatest. The flexibility of the procedure at the debriefing site was increased to take greater advantage of any medical symptoms which might appear. The MA-7 pilot was aeromedically prepared for flight in a manner similar to that of the MA-6 pilot with allowance made for individual variations, for example, dietary preferences and the mode of physical conditioning. Prior to the mission, clinical observations were obtained during several medical examinations and before most of the preflight activities listed in table 5-1. The medical examinations are. logically divided into a clinical history followed by physical examination. This latter division consists of standard medical procedures, including repeated and numerous observations by physicians, routine and special laboratory tests, X-rays, retinal photography, electrocardiography, electroencephalography, and special tests of the body s balancing mechanism.

The threefold purpose of the clinical observations was (1) to determine the fitness of the astronaut for flight, (2) to provide baseline information for the AeromedicaI Flight Controllers, and (3) to measure any changes which might have occurred between preflight and postflight conditions.

 [44] Table 5-I. Significant Activities of MA-7 Astronaut

For purposes of these observations, the aeromedical history of the MA-7 mission began on April 30, 1962, with Astronaut M. Scott Carpenter's arrival at Cape Canaveral, Fla., for preflight preparations. A summary of his significant activities from this date until his return to Cape Canaveral following the flight is presented in table 5-I. Throughout this period, his physical and mental health remained excellent. A special diet which insured good nutrition and hygiene was used for 19 days before the flight. Mission rescheduling caused two starts on the low-residue diet before the third and final 3-day low-residue diet began on May 21, 1962. The pilot maintained his physical condition...

...through frequent exercise on n trampoline (fig. 5-1) and distance running.

On the morning of the flight, Astronaut Carpenter was free of medical complaints, mentally composed, and reedy for the mission.. Breakfast consisted of filet mignon, poached eggs, strained orange juice, toast, and coffee. The preflight fluid intake consisted of 1,050 cc of water, juice, coffee, and sweetened iced tea. He voided three times into the urine collection device before launch. The events of the aeromedical countdown are listed in table 5-II. Astronaut Carpenter was awakened 65 minutes earlier shall the MA-6 pilot had been and the MA-7 launch was 122 minutes earlier than the MA-6 launch.

After the flight, Astronaut Carpenter stated. "My status is very good, but I am tired." His fatigue at landing is attributable to the heat load accompanying an elevated suit temperature (see paper 1) and the associated high humidity, the activity required to carry out the flight plan, and the expected emotional stress associated with such a flight. The following postlanding sequence of events contributed further to his fatigue after entering the raft, he recognized that it was upside down. He left the raft, held to the spacecraft, righted the raft, and once...

 [45] Table 5-II. MA-7 Aeromedical Countdown Events

....again climbed aboard. His neck dam was still stowed, and, after several fatiguing attempts, he was able to deploy it some 30 minutes after his second entry into the raft. An undetermined but moderate quantity of water had entered the pressure suit. Obviously, these events represent survival hazards. Astronaut Carpenter drank water and ate food from his survival kit during the 3-hour period awaiting helicopter pickup.

Throughout the debriefing period, he talked logically about his space flight and remained alert. A detailed review of the pilot's in-flight aeromedical observations is presented in another section of this paper.

Abbreviated physical examinations were accomplished by the Astronaut Flight Surgeons prior to most of the planned activities in the prelaunch period. These examinations revealed no significant variations from previous examinations. ions. The aeromedical debriefing team, representing the specialties of internal medicine, neurology, ophthalmology, aviation medicine, psychiatry, radiology, and clinical laboratory conducted a comprehensive medical examination 7 days before the mission. This examination included special labyrinthine studies (modified caloric test and balance test on successively more narrow rails), electrocardiogram (EGG), electroencephalogram (EEG), and audiogram. Astronaut Carpenter was in excellent health and showed no significant change from previous examinations

On the night prior to the flight, the pilot obtained approximately 3 hours of sound sleep. No sedative was required. He was given the final cursory preflight examination by the same specialists in aviation medicine, internal medicine, and neuropsychiatry who carried out the earlier extensive medical checks. His physical and mental status was normal.

After a 3-hour period in the liferaft, Astronaut Carpenter was examined in the helicopter. The physician reported as follows: "He pulled the tight rubber collar [neck dam] from his neck and cut a hole in his [left] rubber pressure-suit sock to drain out sea water He was anxious to talk and to discuss his experiences in n cooperative and well-controlled manner. He talked n with the helicopter pilot, paced about a bit, and finally relaxed as one normally would after an extended mental and physical exercise." The physical examination aboard the aircraft carrier revealed that he was without injury and in good health. He did show a mild reaction to the adhesive tape used at the four FOG sensor sites and the blood-pressure microphone location.

Upon Astronaut Carpenter's arrival at Grand Turk Island (10 hours after the landing), the internist member of the debriefing team noted: "He entered the dispensary with the air and the greeting of a man who had been away from his friends for a long time. He was alert, desiring to tell of his adventure and seemed very fit . . . his appearance and movement suggested strength and excellent neuromuscular coordination ." A brief medical examination was undertaken an flour after the pilot's arrival. The following morning' a comprehensive examination was made by the same group of specialists who had examined Astronaut Carpenter 7 days prior to space flight.. This extensive examination revealed no physical changes from the pilot's preflight condition. Specifically an audiogram, EEG, ECG, chest X-rays, balance, neuromuscular coordination, and mental status were all normal. No evidence of cosmic-my damage was found during the ophthalmologic examination, which included slit lamp biomicroscopy. The aeromedical debriefing was completed on the second morning following the flight. The results of these examinations [46] are presented in tables 5-III [5-IV] to 5-V. A mild asymptomatic urethrisis was present in both preflight and postflight examinations. Treatment was withheld until after the flight.

[48] Aside from moderate tiredness based upon long hours of work and few hours of sleep, Astronaut Carpenter remained ill excellent health throughout the debriefing period.. He returned to Cape Canaveral on May 27, 1962, ready to "do it again."

The blood and urine chemistries studied were similar to those examined in previous manned space flights (see bibliography). The results of the MA-7 blood chemistry studies are summarized in table 5-VI. The level of the blood chloride and alkali metals remained stable throughout trout the period of observation. There was a slight lowering of blood calcium on the second day after the MA-7 mission.

The urinary output of calcium (table 5-VII) for this period showed a total of 10.67 milli-equivalents (mEq) of calcium excreted during the 17 1/2-hour period which included the flight and the immediate postflight period. In the subsequent 28 hours, 16.25 mEq of calcium were excreted. The fact that the potassium excretion was also elevated in the same period of time suggests that this increased calcium output is a result of n variation in kidney activity rather than just calcium mobilization alone. The stability of the blood potassium values, moreover, indicates that the loss of potassium was well compensated. During this period, Astronaut Carpenter's urine was consistently acidic with a pH near 5.0.

A comparison of similar data obtained from Astronaut Glenn during the MA-6 mission is also shown in table 5-VII. The MA-6 pilot eliminated 9.11 mEq of calcium during the initial 18- hour period (table 5-VII) and 18.32 mEq during the subsequent 28 flours. However, his blood calcium did not change significantly with values of 4.3, 4.2, and 4.4 mEq/l corresponding approximately in time to similar samples taken on Astronaut Carpenter (table 5-VI). Study in future space flights should help to determine if the difference in blood value for calcium is an individual variable or a truly significant difference.

Table 5-VI.-Blood Chemistry Summary
Determination1	Preflight	Postflight
	- 2 days	+ 10 1/2 hr	+ 45 hr
Sodium, mEq/l	141	137	139
Potasium, mEq/l	4.0	4.4	4.3
Calcium, mEq/l	4.8	4.1	3.5
Chloride, mEq/l	107	105	102
Protein (total), g/100ml	6.9	6.4	6.6
Albumin, g/100ml	3.6	3.2	3.4
Albumin-Globulin ratio	1.1	1.0	1.1
Epinephrine, micrograms per liter (µg/l)	0.2	0.2	0.2
Norepinephrine, micrograms per liter (µg/l)	(2)	6.3	6.3

 

¹ All blood chemistry determinations were done on plasma.

² Value too low to measure accurately on sample furnished for preflight examination.

An attempt was made to control fluid and electrolyte balance through adequate hydration during the MA-7 mission. However, this balance was complicated by problems of high suit-inlet temperature and the associated sweating plus the increased fluid intake used to compensate for this.

A summary of Astronaut Carpenter's fluid intake and urine output is presented in table 5-VIII. In spite of the excess of intake over output, the pilot lost ± 1 pounds (table 5-III). This fact, combined with slight hemoconcentration after flight, the low specific gravity of 2,360cc "in-flight" urine specimen and the urinary electrolyte values, leads to the opinion that a moderate diuresis occurred. Such a diuresis can be explained through the suppression of antidiuretic hormone (ADH) secondary to such factors as the relative water loading both before and during the mission and the normal supine position of the astronaut when in the earth's gravity.

^a 30cc of blood drawn at 5:20 p.m.

^b Total of 2,360 cc in urine collection device; division into preflight and in-flight aliquots is estimated.

^c Time unknown, approximately 7:45 a.m. to 3:40 p.m.

For both the MA-6 and MA-7 missions, a questionnaire and two special tests were utilized to elicit or measure any effect of space flight. and its attendant weightlessness upon the human vestibular apparatus. The first of these tests was a modified caloric test (see fig. 5-2) which is considered to be a valid and finely discriminating index of semicircular canal function. The subject's ear was irrigated for 45 seconds with water below body temperature which could be warmed or cooled under precise control. The times of onset and duration of nystagmus (fine eye jerk) were noted. The highest water temperature which caused nystagmus was regarded as the threshold value. Usually this is 3° to 5° centigrade below body temperature. In patients with clinical vestibular disease, the threshold temperature is usually lower than normal, and, during the course of the disease, it exhibits moderate variation in magnitude.

Astronaut Glenn exhibited no significant change in threshold temperatures be-fore and after his orbital space flight. Astronaut Carpenter likewise did not. show a significant change between tests carried out 6 months prior to flight and the two tests conducted after the flight. Slightly higher threshold temperatures for both left and right ears were obtained at the time of the preflight evaluation (7 days prior to the flight). However, in this instance, these high threshold values were the result of a technical error.

The other labyrinthine tests measured the subject's ability to balance himself on successively more narrow rails, similar to the rails of a railroad track. In this test, the astronaut was required both to stand and to walk heel-to-toe and to keep arms folded on the chest. The standing tests were carried out first with the...

...eyes open, then with the eyes closed. In addition to the influence of fatigue and motivation, the results of this test are affected by several dynamic systems other than the vestibular apparatus, particularly general neuromuscular coordination and position sense.. Normal baseline scores on this test for Astronauts Carpenter and Glenn indicate somewhat higher performance than was found in n group of military flight personnel. Both astronauts showed a small increase in their postflight versus preflight scores on this test. These increments were small and within the expected range of physiological variation. This test represents a relatively quantitative method for evaluating the integrity of a number of neuromuscular mechanisms related to balance. It is not, however, as precise nor as specific a test as is the modified c caloric test.

In both United States manned orbital space flights,, a xylose tolerance test was performed to measure intestinal absorption while the astronaut was weightless. This test requires the astronaut to ingest a 5.0-gram xylose tablet while weightless, followed by urination just prior to return to 1 g. Unfortunately the urine collected during weightlessness from that collection device does not separate the urine passed before and after the flight; therefore, it was not possible to determine the absorption of xylose during weightlessness as was done in the MA-6 mission. Control studies on both the MA-6 and MA-7 were set up to simulate, in time, programed in-flight times for xylose ingest ion and subsequent urination. However, the xylose-tolerance test accomplished during the MA-7 mission differed significantly from the same test which was successfully accomplished during the MA-6 mission. In accordance with the flight plan, the 5-gram xylose tablet was ingested at 2 hours 41 minutes 35 seconds -g g.e.t. in the MA-7 mission instead of at 23 minutes 11 seconds g.e.t. as was done in the MA-6 mission. Through a later in-flight xylose ingestion time, it was hoped that any gastrointestinal changes would be more pronounced after a slightly longer (138 minutes) exposure to weightlessness. Also, the weightless absorption and excretion of xylose would then take place, if it followed the curve of normal xylose urinary excretion, during the period of maximum anticipated absorption and excretion. The other significant variable was the marked increase in fluid intake by Astronaut Carpenter over that of Astronaut Glenn. Both astronauts had demonstrated a normal response in the preflight period when compared to five control subjects. Astronaut Glenn produced only 800 cc of urine and excreted 34.9 percent of the test xylose dose during his 4 1/2-hour period of weightlessness. When compared with his control excretion of 38.2 percent in the preflight period, this in-flight result is normal. Astronaut Carpenter produced 2,360 cc of urine during the flight collection period and excreted 22.5 percent of the xylose (figure 5-3). When the single urine specimen passed aboard ship at 5 p.m. e.s.t. is included in the test period, a total....

[52].... of 25.7 percent of the xylose was excreted. The latter specimen extends the elapsed time following the in-flight xylose ingestion to 6 hours and 10 minutes The excretion of only 25.7 percent is significantly less than the 35 percent recovered after 5 hours in the preflight control study period. This decreased xylose excretion is difficult to interpret because of the following circumstances: (1) the pilot is not certain when he urinated during the mission, (2) another specimen was passed approximately 2 hours after landing while he awaited recovery and (3) normal control studies of xylose absorption allowing for such large volumes of fluid intake and urinary output were not obtained prior to flight. There is a remote possibility that the recovered xylose was absorbed and excreted after landing. However, in the MA-6 flight, normal xylose absorption did occur during weightlessness, The normalcy of such absorption during the MA-7 flight cannot be verified. If this test is to be used on future flights, the accurate timing of xylose ingestion and urination must be known Ideally, urine specimens passed while the subject is under the influence of gravity should be separated from those specimens voided while he is weightless. The current urine collection crevice does riot provide for such a separation. Nevertheless, in general terms, both the MA-6 and MA-7 pilots reported no abnormal gastrointestinal symptoms during their missions. Likewise, they related that bladder sensation and function were normal.

In previous flights, a number of enzymes have been studied to evaluate variations of muscle or liver activity resulting from acceleration followed by a weightlessness period or from the prolonged semi-immobilization of the astronaut. Neither the MR-3, MR-4, nor MA-6 pilot showed significant change in transaminase or aldolase activity. No increases in acetylcholine activity have been demonstrated. The dehydrogenases examined have included glutamic, alpha- ketoglutaric, isocitric, malic, and lactic dehydrogenases. Of these, only lactic acid dehydrogenase has shown any appreciable change and this has been consistent in each flight. In the MA-6 flight, the lactic acid level was increased. Increases have also been noted in leucylamino peptidase activity and in phosphohexose isomerase. Since these were consistent findings in all previous flights, an effort was made in the MA-7 flight (table 5-IX) to study only those enzyme systems reflecting change. These evaluations will be. elaborated further to study heat stability of the enzyme systems and to determine the Michaelis-Menton constants (KM) for the enzyme reactions. These additional determinations may allow an evaluation of the tissue of origin.

Acknowledgements. - The authors greatly appreciate the assistance rendered by the following...

[53]...individuals: Paul W. Myers, M.D., and Charles C. Watts, Jr., M.D., Lackland Air Force Hospital, San Antonio, Tex.; George Ruff, M.D., University of Pennsylvania; W. Bruce Clark, M.D., USAF School of Aerospace Medecine, San Antonio, Tex.; Carlton L. Stewart, Lackland Air Force Hospital, San Antonio, Tex.; Evan W. Shear, M.D., USAF Hospital, Wright- Patterson Air Force Base, Ohio.Richard A. Rink, M.D.., Brooke General Hospital, Fort Sam, Houston, Tex.; Rita M. Rapp, NASA Manned Spacecraft Center; Walter Frajola, Ph.D., Ohio State University; Kristen B.Eik-Nes, MD., University of Utah; and Hans Weil-Malherbe, M.D., St. Elizabeths Hospital, Washington, D.C.; Beatrice Finklestein, Aeromedical Laboratory, Wright- Patterson Air Force Base, Ohio.

1. DOUGLAS, WILLIAM K., JACKSON, CARMAULT B., JR., et al.: Results of the MR-4 Preflight and Postflight Medical Examination Conducted on astronaut Virgil J. Grissom. Results of the Second U.S. Manned Suborbital Space Flight, JuIy 21, 1961. NASA Manned Spacecraft Center, pp. 9-14.

2. JACKSON, CARMAULT B., Jr., DOUGLAS WILLIAM K., et al.: Results of Preflight and Postflight Medical Examinations Prof. Conf. on Results of the First U.S. Manned Suborbital Space Flight, NASA, Nat. Inst. Health,, and Nat. Acad. Sci. June 6, 1961, pp. 31-36.

3. MINNERS HOWARD A., DOUGLAS, WILLIAM K., et al.: Aeromedical Preparation and Results of Postflight Medical Examinations. Results of the First United States Manned Orbital Space Flight, February 20, 1962. NASA Manned Spacecraft Center, pp. 83-92.

Xylose:

BUTTERWORTH, C.E., PEREZ SANTIAGO, ENRIQUE, MARTINEZ-DE JESUS, JOSE, and SANTINI RAFAEL: Studies o the Oral and Parenteral Administration of D (+) Xylose. Tropical Sprue, Studies of the U.S. Army's Sprue Team in Puerto Rico, Medical Science Publication No.5, Chapter 18, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, D.C., 1958.

Glucose:

NELSON, M.: Photometric Adaptation of Somogyi Method for Determination of Glucose. Jour. Bio. Chem., vol.153, 1944, pp. 375-380.

Total protein, albumin:

COHN, C., and WOLFSON, W.G.: Studies in Serum Proteins. I-The Chemical Estimation of ALbumin and of the Globulin Fractions in Serum. Jour. Lab. Clin. Med., vol.32, 1947, pp. 1203-1207.

GORNALL, A.G., GARDAWILL, C.J., and DAVID, M.M.: Determination of Serum Proteins by Means of Biuret Reaction. Jour. Biol. Chem., vo. 177, 1949, pp. 751-766.

Urea nitrogen:

GENTZKOW, C.J., and MASEN, J.M.: An accurate Method for the Determination of Blood Urea Nitrogen by Direct Nesslerization. Jour. Biol. Chem., vol.143, 1942, pp. 531-544.

Calcium:

DIEHL, H., and ELLINGBOE, J.L.: Indicator for Titration of Calcium in Presence of Magnesium With Disodium Dihydrogen Ethylene Diaminetetraacetate. Anal. Chem., vol.28, 1956, pp. 882- 884.

Chloride:

SCHALES, O., and SCHALES, S.S.: A Simple and Accurate Method for the Determination of Chloride in Biological FLuids. Jour. Biol. Chem., vol.140, 1941, pp. 879-884.

Epinephrine and norepinephrine:

WEIL-MALHERBE, H. and BONE, A.D.: The Adrenergic Amines of Human Blood. Lancet, vol. 264, 1933, pp. 974-977.

GRAY, I., YOUNG, J.G., KEEGAN, J.F., MEHAMAN, B., and SOUTHERLAND, E.W.: Adrenaline and Norepinephrine Concentration in Plasma of Humans and Rats. Clin. Chem., vol.3, 1957, pp. 239-248.

Sodium potassium by flame photometry:

BERKMAN, S., HENRY, R.J., GOLUB, O,J., and SEAGALOVE, M.: Tungstic Acid Precipitation of Blood Proteins. Jour. Biol. Chem., vol.206, 1954, pp.937-943.

Vanyl mandelic acid:

SUNDERMAN, F.W., et al.: A Method for the Determination of 3-Methoxy-4-Hydroxymandelic Acid ("Vanilmandelic Acid") for the Diagnosis of Pheochromocytoma. Am. Jour. Clin. Pathol., vol. 34, 1960, pp. 293-312.

Heat-stable lactic dehydrogenase:

STRANDJORD, PAUL E., and CLAYSON, KATHLEEN C.: The Diagnosis of Acute Myocardial Infarction o the Basis of Heat-Stable Lactic Dehydrogenase. Jour. Lab. Clin. Med., vo. 58, 1961, pp. 962-966.