1. The numerous objectives of the Mercury animal test program were met. The MR-2 and MA-5 tests preceded the first ballistic and orbital manned flights, respectively, and provided valuable training in countdown procedures and range monitoring and recovery techniques. The bioinstrumentation was effectively tested and the adequacy of the environmental control system was demonstrated.
  2. A 7-minute (MR-2) and a 3-hour (MA-5) exposure to the weightless state were experienced by the subjects in an experimental design which left visual and tactile references unimpaired. There was no significant change in the physiological state or performance of the animals as measured during a series of tasks of graded motivation and difficulty.
  3. Questions were answered concerning the physical and mental demands that the astronauts would encounter during space flight, and it was shown that these demands would not be excessive.
  4. It was also demonstrated that the young chimpanzee can be trained to be a highly reliable subject for space-flight studies.

The suborbital ballistic flight of Ham on January 31, 1961, was the prelude to Alan R. Shepard's suborbital space flight, while the orbital flight of Enos on November 29, 1961, preceded the orbital flight of John H. Glenn.

The fact that we now categorize these events as belonging to the rather distant past, although they occurred only about 4 years ago, serves to emphasize the pace of development in the exploration of space. While the chimpanzee program may pale in the light of subsequent successes, its scientific and technological contribution should not be overlooked.

The significance of this project can be fully appreciated, and its contribution judged, only by considering the lack of knowledge existing at the time of its conception. In addition to its essential training function, this project verified the feasibility of manned space flight through operational tests of the Mercury life-support system. It demonstrated that complex behavioral processes and basic physiological functions remained essentially unperturbed during brief exposures to space flight. The Mercury chimpanzee program marked the first time that physiological and behavioral assessment techniques were combined for evaluating the functional efficiency of the total organism in space.

Perhaps the ultimate contribution of this program was in providing the framework of knowledge upon which future scientific experiments on biological organisms, exposed to flights of extended durations, must be based. Biosatellite experiments designed to seek more subtle and elusive effects of prolonged space flight on biological functioning will require even more refined and difficult techniques, but will depend heavily on the groundwork laid in these early steps of Project Mercury.

A summary of the more important animal suborbital and orbital flights during the period 1957 to 1964 is presented in [table VII].

In another NASA-supported flight, NERV 1, various experiments were carried in a suborbital flight of 20 minutes. Neurospora molds showed a surprisingly high level of mutation, but the control molds also had high rates.

The Discoverer XVII and XVIII flights, to which the Air Force contributed, resulted in many interesting findings relative to the responses of living systems to space flight. On the Discoverer XVII flight, samples of human gamma globulin and rabbit antiserum specific for human gamma globulin showed an increase in reactivity, and samples of synovial and conjunctival cells showed no changes in their cytological characteristics.

Discoverer XVIII was launched during a massive solar flare which lasted for the first 13 hours of the 48-orbit, 3-day flight. Neurospora conidia, nerve tissue, algae, human bone marrow, eyelid tissue, gamma globulin, and cancer cells were put in orbit. The results indicated that biological specimens may be able to withstand radiation from solar flares with a minimum of shielding and that aluminum shielding may be better than lead.

In 1949, the U.S.S.R. began a systematic, uninterrupted research program in biological space experimentation. They have studied the effects of physical stress, immune reactions, psychobiology and behavior, genetics, and responses to environmental factors such as spacecraft dynamics and ambient radiation. The organisms and biological materials included tobacco mosaic and influenza viruses; T2 and T4 bacteriophage; Bacillus aerogenes; lysogenic bacteria; Clostridium butyricum; Escherichia coli; actinomycetes; yeasts; Chlorella pyrenoidosa; seeds of fir, pine, onion, corn, lettuce, wheat, cabbage, carrot, buckwheat, cucumber, beet, Euonymus, fennel, mustard, pea, broad bean, tomato, and nutmeg; Tradescantia paludosa; Ascaris eggs; snail spawn; Drosophila melanogaster; loach roe; frog eggs and sperm; guinea pigs; mice; rats; hamsters; rabbits; dogs; monkeys; human and rabbit skin; HeLa tissue cultures and other tissues (refs. [ref.167] and [ref.168]).