152 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



darkening in planetaiy atmospheres, both at infrared and at micro- 

 wave wavelengths, with particular reference to the atmosphere of 

 Venus. Preliminary results predict only a moderate microwave limb- 

 darkening from expected absorbers in the lower Cytherean atmos- 

 phere. The model of the Jovian red spot, which assumes it to be a 

 floating object, was examined and shown to be unlikely. 



Dr. Sagan was a coexperimenter on the infrared radiometer of the 

 U.S. spacecraft Mariner 11, The experimental results indicated dis- 

 tinct limb-darkening in the 10-micron region and no clear breaks in 

 the Cytherean cloud layer. Dr. Sagan is also an experimenter for an 

 infrared spectrometer designed for a forthcoming Mars fly-by mission. 



Study of the rings of Saturn continues. Dr. Allan F. Cook and 

 Dr. Fred Franklin are undertaking a more accurate scattering theory 

 for the sunlight illuminating the rings and a more accurate solution 

 of the Boltzmann equation for the ring particles.' 



A theoretical mvestigation of the formation of absorption bands in 

 a multiple scattering atmosphere was conducted by Dr. William M. 

 Irvine. His investigation of strongly asymmetric multiple scatter- 

 ing is continuing, with emphasis on the variation in limb-darkening 

 as a function of asynmietry factor and optical depth. 



The existing theories of motion of the major planets are not satis- 

 factory from the modern point of view, especially not for the require- 

 ments of space travel. Their improvement, however, is hardly 

 conceivable without progress in computer teclmology. Mr. Izsak is 

 therefore considering the possibility of using digital computers for 

 the construction of analytical perturbation theories. As a first step, 

 a very efficient program has been developed for the computation of 

 Laplace coefficients and their derivatives. With cooperation from an 

 MIT team, a program has been written for the construction of symbolic 

 expressions, called the Newcomb operators. At present, a generaliza- 

 tion of these results is being investigated, together with their applica- 

 tion to the problem of close commensurabilities in celestial mechanics. 



The orbits of the minor planets present problems which Dr. Don A. 

 Lautman is considering. An analysis of the distribution of the peri- 

 helia of the minor planets has been completed.^ Dr. Lautman and Dr. 

 Colombo have examined the small-amplitude librations of a particle 

 near the triangular point in the semirestricted three-body problem. 

 They are extending this research to an analysis of orbits of minor 

 planets whose periods are commensurate with that of Jupiter. 



The origin of the solar system and the production of isotopes in 

 protoplanets are the areas Dr. Ilenri Mitler is studying. A com- 

 parison of theoretical results with observations may allow a choice 



See footnotes on p. 164. 



