|
Selection of Male & Female Candidates for Space Flight :
Aeromedical Aspects & Role of IAM
by
Gp Capt MM Dogra
Sr Adviser (Av Med)
IAM, IAF
The wisdom of the adage "an ounce of prevention is worth a pound of cure" is profound with regard to planning human activities in the hostile, isolated environment of Space Flight - Albert W Holland & Royden W Marsh. (1)
Aerospace Medicine is principally preventive medicine. The process of astronaut / cosmonaut selection is as such a comprehensive medical programme which encompasses understanding the requirements of the job content of the space crew and the physiological and psychological effects the stresses of space flight would induce. Consequently the selection process would visualize the following broad principal areas :- (9)
(a) To survive in the space vehicle environment eg. micro gravity, pressure/gaseous changes
(b) To perform under space flight stresses.
(c) To monitor and operate controls and instruments in case of information failure.
(d) To scientifically observe and report beyond what instruments can do, and
(e) To control and improve flight systems and sub systems like a true test pilot.
AEROMEDICAL ASPECTS
Having defined the broad mission requirements, the aeromedical selection process next envisages the aeromedical problems the space crew encounter during the mission (3). Some of the important stresses are :-
(a) 'G' Forces - Large acceleration forces are encountered during lift off, re-entry, parachute deployment and landing. Earlier flights encountered 8-10 G forces, which has reduced in magnitude as the space shuttles evolved. Currently a space crew encounters 3-4 G for 3-4 minutes on lift off and 1.5 -1.8 G for 5 minutes on re-entry.
(b) Weightlessness - Weightlessness or microgravity is encountered by space crew as a resultant of gravitational and inertial forces. Microgravity induced pathophysiology (MIP) includes -
- Body fluid redistribution
- Reduced total body water and plasma volume
- Reduced total RBC mass
- Cardiac deconditioning
- Neurovestibular changes
- Serum electrolyte changes
- Skeletal muscle changes
- Bone demineralization
These changes lead to post flight orthostatic intolerance, postural imbalance, post flight in-coordination, antigravity muscle tone reduction and changes in bone calcium content.
(c) Spacecraft Atmosphere - Artificial Gas Atmosphere provided in the spacecraft has changed over the years Mercury, Gemini and Apollo mission had 0.33 atmosphere pressure with 100% oxygen. Space shuttles have sea level pressure and composition where as the Sky Lab cabin had 0.33 atmospheric pressure with a 70% oxygen and 30% nitrogen content. Soviets however use 20% oxygen and 80% nitrogen at sea level pressure.
(d) Radiation - Flight duration, trajectory and spacecraft shield can limit the possible radiation exposure, a possible hazard.
(e) Psychological stresses - The main areas of concern to Psychologists with regard to long space flights include extended periods of confinement, separation from traditional social support, reduced sensory stimulation and loss of privacy. These stresses can lead to mood disturbances, sleep loss, conflict and work problems. Performance decrement can lead to limitations in mission accomplishment. Psychological factors have been reportedly responsible for three medical evacuations from Soviet missions. Psychological elements of extended space flight and habitation become increasingly important as missions lengthen and become more remote from earth. Missions to Mars are expected to take 2-3 years. Mir space station worked for over 15 years and the longest stay by a cosmonaut was 438 days in 1994-95. Both the US and Soviet space programmes include extensive psychological testing as part of astronaut / cosmonaut selection process.
India opened her space frontier when Sqn Ldr Rakesh Sharma became the first Indian cosmonaut, and the 138th man in space on 03 Apr 84. He spent 7 days on Salyut 7, a Russian spacecraft. IAM thus got involved in the selection of a cosmonaut in 1982-84 culminating in joint Indo-Soviet space flight and subsequently astronaut selection in 1984-86 for a joint Indo US space flight. The selection process for a payload specialist (PS) for the latter space flight planned for 1986 was completed, although the joint venture did not take place. Needless to say the essence of the medical evaluation process was undertaken at the Institute of Aerospace Medicine, CHAF and AFIDS at Bangalore. However, the coordination of medical evaluation including the portions carried out in peripheral medical centers and the final selection was done at IAM.
Medical standards applied for astronaut/cosmonaut candidates have been developed and modified over the years. IAM broadly followed the protocols for medical evaluation as followed in the concerned countries for each of the joint ventures. A comparative list of medical tests specified for both astronaut and cosmonaut selection is as follows (9) -
Astronaut & Cosmonaut Selection : Medical Tests
COSMONAUT SELECTION AT IAM
Medical evaluation process for an Indian cosmonaut started in 1979. The joint Indo-Soviet project followed guidelines issued by the Soviets. The selection process laid down was to be carried out in 3 stages.
(a) StageI - Covers OPD evaluation by various specialists with a detailed history as per the prescribed questionnaire. At this stage it is decided whether a candidate is fit/unfit for hospital examination.
(b) StageII - This stage is a hospital evaluation with the aim to detect any latent pathology, early disease and functional endurance capabilities of various systems. It includes thorough clinical and laboratory investigation including psychological evaluation. Endurance capabilities to be evaluated in respect of cardio-pulmonary parameters on till table studies, LBNP, 'G' tolerance on Human centrifuge and are graded as good, satisfactory and poor.
(c) StageIII - This evaluation is for the final selection and is carried out at Yuri A Gagarin Cosmonaut Training Centre. Basically all test results conducted so far are reviewed and involves 1 week in-patient evaluation at Central Military Aviation Hospital (CMAH) for military candidates and at Institute of Bio-Medical Problems (IBMP) for civilian candidates. After selection, the cosmonauts undergo annual certification examination.
The actual process in respect of Indian Cosmonaut candidates was modified. All the candidates being from a pre selected military background and mostly test pilots, stage-I and stage II were completed at IAM, Bangalore. A total of 60 pilots were screened and 20 were called for evaluation. 12 of them were short-listed for stage II evaluation. There was some amount of overlapping in the stages and all the candidates did not undergo all the tests, as there was a continuous process of pruning at various levels. Some of special areas of medical evaluation carried out on these candidates are elaborated :-
- Physiological stress Testing (n-30) (5)
- Spirometry
- Bicycle ergometry with ECG and VO2 max assessment
- 70 degree HUT
- Cold pressor Test
- Cardiovascular Evaluation (n-12) (2)
- ECG Resting and during stress
- Echocardiography
- VCG
- Acceleration Stress on Human Centrifuge (7)
- +Gz (n-12) 5G for 30 sec with onset/decay rests of 0.2 G/Sec
- +Gx (n-9) 8G for 40 sec with onset rate of 0.5G/Sec and decay rate of 0.2G/Sec.
- Vestibular System (n-16) (4)
- Otolith Reaction time
- Khilov's swing Test
- Continuous cumulative coriolis acceleration (CCCA) Test
- Discontinuous cumulative coriolis acceleration (DCCCA) Test
- Psychological Evaluation Tests (n-12) (8)
- 16 PF Test
- MMPI
- TAT Indian version
- Rosenswieg's personality questionnaire for Stress tolerance
- Correction Test - vigilance task in high noise environment (Perceptual test)
- Dental Evaluation (6)
- Stomatoscopy
- Electro odonto diagnostics and thermal test
- Complete stomatological panoramic Radiograph (Orthopantograph)
Soviet team of aeromedical specialists associated themselves with their Indian counterparts for 2nd part of phase II evaluation where nine candidates were evaluated in Jul 82 and five were short-listed for phase III selection in the USSR. Finally four candidates were sent to USSR in Aug 82 where all four were found fit and returned to India for final selection of 2 candidates by Air Headquarters'. Incidentally, one country which had sent a cosmonaut in a Soviet spacecraft earlier, had sent 100 candidates and only 3 were found fit. Standard of medical evaluation at the IAM was found to be extremely praiseworthy. During their training over next 18 months, they underwent an annual medical evaluation at Gagarin Cosmonaut Training Centre and a pre-launch evaluation at Baikanoor.
ASTRONAUT SELECTION AT IAM
Astronaut selection is done by NASA, basically in 2 tiers. A joint Indo-US space flight was planned in the space-shuttle Challenger and the selection of the candidates from the Department of Space, Government of India, started in Dec 84. Teams of specialists from IAM visited VSSC, Trivandrum, SAC Ahmedabad, SHAR Madras, SHAR Sriharikota and ISRO liasion cell Bombay for tier-I phase-I medical screening process. Based on the guidelines given in NASA Medical Survey Questionnaire, doctors from ISRO and the visiting IAM teams screened a total of 89 candidates (84 males and 05 Females) at various ISRO centres. 29 candidates (28 Males and 01 Female) were found fit for phase II of tier I of medical evaluation in early 1985. This was followed by selection of 04 candidates by IAM. 02 candidates were presented to Johnson Space Centre, Houston, 12 months prior to the flight i.e. in Jun-Jul 85 for final medical evaluation and 02 candidates kept in India as reserves. Both the candidates were found fit by NASA authorities., which was another feather in IAM's cap. Both candidates started their training for the planned biomedical experiments at IAM. The space flight was planned for Jun-Jul 86. Indian astronaut was selected as a payload specialist (PS) for deployment of INSAT-IC. Additionally, life-sciences experiments were also planned by IAM. However, the mission was prematurely terminated due to the unfortunate accident of the space-shuttle Challenger.
The standards of medical evaluation applied for this selection were the same as brought out in para 5 earlier. However the standards of selection for a Payload-Specialist (PS) as prescribed by NASA are compartively lenient in some areas. The differences in the Medical Standards NASA class I-IV space flight participants are elaborated below: - (9)
Table - 1
DIFFERENCES IN MEDICAL STANDARDS FOR NASA CLASS I, II, III AND IV SPACE FLIGHT PARTICIPANTS
| Item |
Pilots
(Class I) |
Mission Specialist
(Class II) |
Payload specialist
(Class III) |
Space Flight
for participants
(Class IV) |
| Distant Vision |
20/50 or better
uncorrected;
correctable to 20/20 each eye |
20/15 uncorrected;
correctable to
20/20 each eye |
Correctable to
best eye |
same as Class
III |
| Near vision |
uncorrected <20/20
each eye |
uncorrected <20/20
each |
not specified |
not specified |
| Hearing vision |
each ear :
30 db @ 500 Hz
25 db @ 1,000 Hz
25 db @ 2,000 Hz
50 db @ 4,000 Hz |
same as Class I |
better ear :
35 db @ 500 Hz
30 db @ 1,000 Hz
30 db @ 2,000 Hz |
must hear
whispered
voice at 3ft
(hearing aid
allowed) |
| Height |
64-76 inches |
60-76 inches |
not specified |
not specified |
Refraction/
Astigmatism
|
specified |
specified |
not specified |
not specified |
Contraction
Visual field
|
15deg |
15deg |
30deg |
not specified |
| Phorias |
eso>15; exo>8
hyper> 2 |
eso>15; exo>8 |
not specified |
not specified
hyper >2 |
| Depth perception |
no errors in 16
presentations of the
Verhoeff stereopter
Test |
same as Class II |
not specified |
not specified |
| Color vision |
pass Farnsworth
lantern
test |
pass Farnsworth
lantern
test |
not specified |
not specified |
| Blood pressure |
140/90 |
140/90 |
150/90 Rx
allowed |
150/90 Rx
allowed |
| Radiation exposure |
<5rem/year |
<5rem/year |
not specified |
not specified |
Further specific details on the medical standards for PS selection (Class III) as well as PS annual review (Class III a) evaluation are given in NASA publication JSC 11571
CONCLUSION
Indian cosmonaut/astronaut were medically selected at IAM and the level of upgradation of knowledge and facilities in this field was significant. The medical evaluation standards achieved and the expertise and thoroughness shown by the specialists at IAM was of the highest standard. Our experiments executed during the Soyuz-7 flight were a tremendous source of encouragement. The Soviets were so appreciative of the 0sphere of activities generated in newer fields like Yoga, that post Soyuz-7, fresh experiments were jointly planned. The cooperation carried on till as late as early 90's under the aegis of Indian Council of Medical Research. It was regrettable that the process was discontinued in early 90's. Follow up plans for experiments in space (9), as defined by NASA, generally relate to three areas enumerated below and experiments were planned accordingly :-
(a) Very short-term studies usually aim to validate ground based predictive tests like on Space Motion Sickness etc.
(b) Longitudinal studies over several missions to see cumulative effect of radiation or bone mineral loss etc.
(c) Longitudinal studies over the whole astronaut career on occupational disease / injuries etc.
|
