Arthur W. Galston, Ph.D. 

 Chairperson 



Peter Vitousek, Ph.D. 



C. Ross Hinkle, Ph.D. 



sate 



Controlled Ecological Life Support Systems 



The Controlled Ecological Life Support Systems (CELSS) Program is a NASA 

 effort to create an integrated, self-sustaining system capable of providing food, 

 potable water, and a breathable atmosphere for space crews on long-term 

 missions. Near-term goals are to understand how human life can be maintained in 

 a stable, autonomous system on Earth and in space, and to develop the 

 technological capacity needed to build autonomous life support systems. The 

 system envisioned will depend on a combination of biological and physicochemical 

 processes in which plant primary production is the raw material for human 

 consumption, and vice versa. 



A person of average size — about 70 kilograms — requires from 0.5 to 0.6 kilo- 

 gram of food, 3.0 liters of water, and from 0.75 to 1.0 kilogram of oxygen each day. 

 Liboratorv research has shown that these needs could be met b\ a bioregenerative 

 life support system using higher plants and or algae. In addition, laboratory 

 estimates indicate that such a system could be effective within the volume 

 constraints of a space vehicle. These laboratory studies need to be verified by a 

 ground-based experimental effort, which would develop design criteria for 

 manned testing leading to a space-based system. This research will take 

 considerable time. To develop the capabilities that may be required for advanced 

 missions undertaken during the next few decades, the CELSS Program requires 

 significant expansion immediately. 



The sections below discuss the major issues relevant to the CELSS Program. The 

 discussion is based on information elicited in part from presentations given by 

 personnel at NASA Headquarters and the field centers, pertinent scientific 

 literature, and reports by past advisory committees (1,2,3). In addition, the CELSS 

 Study Group collected data by examining published program plans and the 

 published results of CELSS research, by interviewing principal investigators and 

 other researchers, and by visiting Ames Research Center (ARC '). fohnson Space 

 Center QSC), and Kennedy Space Center (K>( | 



Issues and Opportunities 



1 I I ss concept may be viewed as three integrated subsystems: 1) a food 



112 



