The study of the effects of unique or unknown space environmental factors will probably yield unexpected results which may drastically modify future technical approaches. The results from these biosatellite studies will have broad application to longer term, manned space flight, including manned space stations and lunar and planetary exploration.
The biosatellite program is a second-generation series of carefully planned and selected experiments, including some highly sophisticated experiments which have required several years of baseline study and equipment development. These orbiting recoverable biosatellites will provide opportunities for critical testing of major biological hypotheses in the areas of genetics, evolution, and physiology.
The scientific community showed great interest in the biosatellite program, and scientists from universities, industry, and Government have submitted 185 flight experiments involving primates and other mammals, vertebrate and invertebrate animals, micro-organisms, and plants.
The selected biosatellite experiments include studies at the cellular, tissue, and organism levels, including embryological development and growth experiments at the tissue level and physiological, behavioral, reproductive, and genetic studies at the organism level. The experiments are divided into six categories:
- Primates
- Mammals (nonprimate)
- Animal, cellular, and egg
- Plant morphogenesis, photosynthesis, and growth
- Biorhythm
- Radiation
Twenty experiments have been selected for flight to study the effects of weightlessness and decreased gravity during 3- to 30-day orbital periods. The experiments include a wide variety of plants and animals from single-celled organisms to higher plants and animals. The effects of weightlessness on the primate will be studied, especially the central nervous, the cardiovascular, and the skeletal systems during 30-day orbits.
Experiments have been selected to study the genetic and somatic effects of weightlessness combined with a known source of radiation (Sr85) to determine if there are any antagonistic or synergistic effects ([ref.172]). Experiments are also included for studying the effects of the unique environment of the Earth-orbiting satellite and removal from the Earth's rotation in relation to biological rhythms of plants and animals.
Six biosatellites are included in the presently approved program, with the first flight in 1966. They will be launched from Cape Kennedy by the improved two-stage, thrust-augmented Thor-Delta into a nearly equatorial circular orbit at an altitude of 180-200 miles for periods up to 30 days. Recovery will be by Air Force airplane during capsule/parachute descent. The spacecraft weigh 1000-1200 pounds, have a 280-pound recoverable capsule and, while in orbit, will not experience greater than 1/10 000 g of acceleration. The life-support system will provide an environment at sea-level pressure of 80 percent nitrogen, 20 percent oxygen, and no more than 0.5 percent carbon dioxide with a temperature of 75° F ±5° F.
All experiments are in various stages of development or testing and flight test hardware has been and is being constructed. The experiments and hardware are being subjected to preflight tests simulating launch and recovery stresses. Rhesus, pigtail, and squirrel monkeys have been subjected to the dynamic forces of the simulated flight under conditions of complete, partial, and no restraint. Three types of centrifuges have been used to simulate the flight profile. Primates were fully instrumented with deep brain electrode implants, implanted catheters, and other implanted sensors. During centrifugation, motion pictures were taken. These primates were semirestrained in form-fitted couches which allowed movement of the body while facing the accelerative force in a ventrodorsal position (eyeballs in). In this series of tests, all primates were normal following the tests and exhibited no unusual behavior or effects. X-rays showed that implanted catheters and electrodes remained in place, and there were no movements causing tissue damage. However, when the primates were placed with their backs toward the accelerative force, dorsoventral (eyeballs out), the animals suffered visible damage. At 6 g there was no visible stress, but at 8 g swelling of the lower eyelids was noticeable. At 11 g both eyelids were swollen shut. In the biosatellite program, primates will be placed in the semirestraint couches in a position facing accelerative forces, ventrodorsal (eyeballs in), to prevent these effects.