120 SPACE BIOLOGY 



For the biologist tlie most fascinat- as revolutionary for human life as the 



ing and challenging of all problems is attainment of a method for using fu- 



the possibility of making a scaled cabin sion energy. 



into a "balanced aquarium" or an auto- On the other hand much attention 



trophic unit dependent only upon the is also being paid to the possibility of 



input of radiant energy from the sun. using cultures of chlorella to augment 



A man is approximately equivalent in the food supply of the world. If opti- 



rate of energy turnover to a 100 watt mum conditions for growth could be 



light and this is in turn about equal supplied, calculations indicate that it 



to the radiation falling on each square is not impossible to make effective use 



foot of surface exposed to the sun. If, of chlorella for this purpose. This, how- 



therefore, this energy could be used ever, involves recovery of all waste 



with sufficient efficiency the problem products in the excreta including nitro- 



is not theoretically insoluble. gen, minerals and water and their addi- 



For this purpose one must either tion to the chlorella culture in useful 



complete the solution of the chemical form. Such a system if successful would 



mechanism of photosynthesis or invoke at least substantially supplement the 



as usual, the aid of plants. Neither of oxygen supply and nutrient supply of 



these methods seems impossible. Great the satellite occupants and it is a prob- 



progress has been made by chemists lem well worthy of the serious con- 



and plant phvsiologists in their study sideration of biologists, 

 of photosynthesis and some day it is By effective participation in these 



probable that a useful test tube process and other problems there are many 



for the removal of oxygen from carbon ways in which biologists will be able 



dioxide or its equivalent of water might to qualify as "first class citizens" in the 



become realized. It would certainly be age which is before us. 



QUESTIONS 



1. If a yeast culture was supplied wdth a 2. What are some of the problems of man 

 three months supply of food, sent aloft in space? 

 for three months in a satellite and re- 

 turned to the earth in a living condi- 3. What is meant by an autotrophic unit 

 tion, what would this prove? designed for a space capsule? 



