Findings and Recommendations 



animals, and humans necessary to develop an understanding of the fundamen- 

 tal biological processes affected by gravitational forces. 



• Develop an advanced biomedical research facility in space to investigate and 

 verify technologies and medical support necessary to enable the planning and 

 implementation of human exploration of the solar system. 



• Develop and test in space a fully operational bioregenerative life support sys- 

 tem^) for future use in solar system exploration. 



• Conduct cooperative missions with other national and international organiza- 

 tions to study the behavior of the biosphere and the origin, evolution, and dis- 

 tribution of life on Earth and in space. 



The following subdivisions of section 2 present more detailed findings and recom- 

 mendations relevant to particular subject areas. 



Human Space Flight 



Most of the major initiatives being considered by NASA involve human space mis- 

 sions of increasing duration — from 180-day rotations on the Space Station, to 

 several months at a possible lunar colony, to 1 to 3 years on a round trip to Mars. 

 For such missions to be possible, NASA's manned space flight program must 

 undergo a decisive transition by the end of this century, surmounting significant 

 problems in biomedicine, technology, and flight operations. The findings itemized 

 below identify the primary challenges involved with human space missions of 

 extended duration. The recommendations indicate the types of ground-based and 

 space research that must be undertaken to resolve the outstanding issues. 



Findings 



• Four challenges potentially limit the duration of human space flight: 



— Physiological deconditioning 



— The biological effects of exposure to ionizing radiation 



- Potential psychological difficulties on the part of the space crew 



- Environmental requirements, including the need of life support on long space 

 journeys. 



• Ground-based experiments can provide significant data in the four areas. This 

 research must, however, be validated and advanced by experimentation in space. 



• Resolution of the concerns in each of the four key areas will require extensive 

 research. 



- Zero gravity cannot be reproduced in ground-based research. Nevertheless, 

 studies with human and animal models on the ground can provide insights 

 into many of the physical effects of weightlessness, such as bone and muscle 

 loss, cardiovascular deconditioning, and changes in fluid balances. Exceptions 

 to this approach include neurovestibular effects and the loss of red blood cells, 

 which require space research. In addition, the human research needed to vali- 



28 



