Life Sciences in the Space Program 



space. Proposed countermeasures for muscle atrophy and skeletal demineralization 

 include the use of exercise treadmills and cycle ergometers, electrical stimulation of 

 muscle groups, and "Penguin suits," which oppose body movement and partially 

 compensate for the lack of gravity on the antigravitational muscles. In addition to 

 the loss of opposing force on antigravitational muscles, it remains to be deter- 

 mined what effect the hemodynamic changes (such as redistribution of blood 

 flow) or endocrine changes (including calcium loss, negative nitrogen balance, or 

 loss of potassium reservoirs) have in development of muscle atrophy associated 

 with space flight. The impact of muscle loss on performance of astronauts in 

 space remains unclear. 



In summary, the questions that need to be addressed include the following: What 

 is the mechanism of osteopenia (loss of bone tissue) that occurs upon exposure to 

 microgravity? Is this osteopenia associated with an increase in crew morbidity, 

 such as from nephrolithiasis (kidney stones)? What are the sequelae of osteopenia 

 from short-duration flights? Will alterations in ionized calcium concentrations 

 incapacitate crew members with cardiac dysrhythmias or pathologic fractures? 

 What countermeasures may be developed to prevent osteopenia and the associated 

 humoral changes? What countermeasures can be developed for the skeletal muscle 

 atrophy associated with microgravity? What is the mechanism by which gravity or 

 inertial forces retard skeletal muscle atrophy? Will osteoporosis of the bone of the 

 ear affect auditory perceptions, much in the way Paget's disease may lead to 

 hearing loss? 



The effect of microgravity on reproductive function in space has been virtually 

 ignored. Are there any effects of microgravity or cosmic radiation exposure during 

 space flight on reproductive function or developmental biology in flight crew 

 members? 



As with cardiovascular research, the fields of neuroscience and endocrinology are 

 likely to be advanced significantly as a result of space-based research. However, as 

 with all scientific research, the appropriate controls must be done. Accordingly, the 

 use of a space-based centrifuge must be considered. 



The role of a human centrifuge in space, employed to abort the deconditioning of 

 bone, muscle, and the cardiovascular system during space flight, has been an 

 intriguing possibility for many years. Much more work needs to be done on 

 centrifuge-simulated g forces and the "dose of centrifugation" required to abort 

 deconditioning before a solid recommendation can be made regarding centrifuge 

 therapy on prolonged space flights. Preliminary centrifuge studies of this type can 

 be carried out in animals on either the Shuttle, or the Space Station, or both. A 

 centrifuge large enough for humans, in space, could only be accommodated on a 

 structure ot approximately the size of the proposed Space Station module. 



Hematology 



A significant decrease in red cell mass has been reported in the Gemini, Apollo, 

 Skylab, and Soyuz flight crews, and this decreased red cell mass cannot be 



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