(1) The effects of sudden reimposition of reentry accelerations and
terrestrial gravity
(2) Changes in body fluid distribution and composition
(3) The effects of violent physical effort on respiratory and
cardiovascular systems in prolonged weightlessness
(4) Central nervous system functions, especially coordination, skilled
motor performance, judgment, and sleep-wakefulness cycles
NASA has emphasized that planning for manned space programs involves a
systematic extension from physiological observations in animals to man,
and finally the establishment of man as part of the man-vehicle system
design. Moreover, these studies require the evaluation of central
nervous, cardiovascular, respiratory, gastrointestinal, and other
systems as a matrix in mutual interdependence. There is particular
interest in the effects of weightlessness on flights exceeding 30 days.
Mammalian flights of about 30 days also merit attention, including the
development of the life-support systems which must precede such a
program. Development of facilities for biological experiments may well
be an important requirement for studies in anticipation of manned
flights of longer duration than Apollo. Unless the biological satellite
programs of the type mentioned above are successful in providing the
necessary data, a manned orbiting laboratory may also be important in
studies of shorter range.