Life Sciences in the Space Program 



Radiation Protection. Extended missions involving humans in space are 

 permissible only if the crew is protected from unacceptable exposure to ionizing 

 radiation, as is indicated in the "Radiation" section of this report. Central concerns 

 within systems engineering are understanding protective requirements and 

 developing effective environmental design solutions for preventing exposure to 

 ionizing and non-ionizing radiation within the spacecraft and during EVA 

 operations (2). A protective system needs to be devised that will shelter the crew 

 from radiation, particularly during periods of high flux, and still allow members to 

 accomplish required tasks. The entire spacecraft cannot be designed for worst case 

 flux levels because of unacceptable weight and volume penalties. Part of the 

 spacecraft, however, might be designed to provide the shielding necessary for 

 missions lasting to and beyond 1 year, should the Nation decide to embark on 

 such ventures. 



Life Support Systems. Mission duration is the most significant factor determining 

 the type of life support systems required on spacecraft. To date, NASA's manned 

 missions have been short enough for life support functions to run on consumable 

 supplies. Of these supplies on manned missions, water and air account for the 

 greatest volume and mass. Although first generation technology exists to partially 

 recycle water and regenerate air, these supplies and the food needed to sustain 

 crews are carried on the spacecraft or, for permanent missions in low-Earth orbit, 

 they can be resupplied from Earth. Regenerative life support systems could be 

 used on the Space Station to reduce logistic requirements and operating costs. 

 Development costs would be significant, however. Nevertheless, some form of 

 bioregenerative or "closed-loop" system must be used for long-duration missions, 

 such as a lunar or Martian colony, as discussed in the "Controlled Ecological Life 

 Support Systems" (CELSS) section of this report. 



One of the key engineering issues is integrating the life support system within the 

 spacecraft and developing the capability to isolate the system from any contamina- 

 tion problems. The integration and isolation requirements must be developed early 

 in the design process. 



We have learned that the Earth's ecosystem has considerable resiliency and 

 tolerance for abuse. Because of its relatively small size and limited variety oi life 

 forms, the closed environment in a space vehicle is vastly different. System 

 resiliency is restricted, and the margins for design error and performance variation 

 may be extremely small. Consequently research and acquisition of experience in 

 closed cycle, environmental life support systems is one of the most important 

 requirements confronting space life sciences. Until we can build and depend on a 

 life support system that will tolerate dynamic interaction with a human crew, we 

 cannot embark upon extended missions to the Moon or to other planets. The type 

 of partially closed life support system envisioned for the Space Station cannot 

 meet the requirements of a lunar base or a Mars mission. Therefore, it is 

 important to implement a research and technology effort to develop options for 

 i, regenerative life support systemv 



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