WEIGHTLESSNESS 



231 



TABLE 8- 1 3. Components or Factors of the Specific Rate Constants for Chemical Reactions, 

 Diffusion, Viscous Flow, and Electrical Conductivity. 



kj 



h 



I) = t\ 2 



kj 



= T 



V 



■SI-t/RT 



-AFt/RT 



E h 



r = transmission coefficient (tau) 

 k = Boltzmann's constant 

 h = Planck's constant 



free energy of activation 

 "jump distance" (the distance be- 

 tween points of rest of the moving 

 species) 

 volume of one mole of fluid 

 ,V ;i = no. of molecules per mole (6 x 10 23 

 E = applied voltage 



A/-'* 

 A 



I 



Note Heat conduction has not yet been studied from this point of view. If volume, voltage and jump 

 distance terms are factored out of the above expressions, they all become the same: the pre-exponential term 

 with dimensions sec -1 ; and hence the specific rate would be dependent only upon the activation free energy 

 for the process. 



WEIGHTLESSNESS 



In this era, on the threshold of space travel, it would be neglectful not to 

 introduce into a chapter on speeds of processes occurring in the living sys- 

 tem, the effects of gravitational force. Man must withstand a gravitational 

 range from high-g conditions on through to the condition of weightlessness, 

 or zero-g. So little has been published to date about those who have orbited 

 the earth for any appreciable time that little can be written here. However, 

 the general principle can be stated that the change in gravitational force on 

 the human body from earth-bound to weightlessness is small relative to 

 other forces. As a general rule, if the parts are fixed in position, they func- 

 tion normally. Solids and contained liquids, then, show no discernible 

 changes in speeds of chemical or physical — and therefore, presumably, bio- 

 logical — processes. 



With the gravitational restriction removed, blood circulation requires less 

 expenditure of energy. Conversely the same expenditure of energy by the 

 constant-pumping heart is able to accelerate the blood flow through the 

 tissues, and provide exhilaration, just as would a slightly higher O, content 

 in the respired air. The first astronaut, Juri Gagarin, reported that he 

 "observed the earth and sang" dur.ing a li-hr orbital flight. John Glenn had 

 similar experiences during a busy 4^-hr flight. Telemetered physiological 

 data demonstrated normal biological functioning while he was weightless. 

 However, after the 25-hr orbital trip of Gherman Titov, he reported that he 

 felt depressed and nauseated during the flight. His successors, Nikolayev 

 and Papov, flew weightless for several days without mishap or reported 

 discomfort. 



