SECRETARY'S REPORT 13 



observations of 73 satellites. The photoreduction division had deter- 

 mined more than 54,000 precise satellite positions reduced to atomic 

 time. Meanwhile, the Observatory had evolved a nmnber of com- 

 puter programs to process observational data, prepare predictions 

 of satellite passages, and provide the means of analyzing atmospheric 

 densities and temperatures, solar radiation, the shape of the earth and 

 similar phenomena. 



The research and analysis division of the Smithsonian unit has pro- 

 duced some of the major scientific results of the U.S. space program, 

 including determinations of the coefficients of spherical harmonics for 

 the earth's gravitational potential, improved geodetic data, a theory 

 of the critical inclination of satellite motion, and, from extremely 

 accurate studies of atmospheric drag, determination of density and 

 temperature in the high atmosphere as a function of time of day, and 

 geographical position and solar activity. 



The space science of the Observatory has extended beyond satellite 

 tracking. Project Celescope, as a part of NASA's orbiting astronomi- 

 cal observatory, is now being developed to make an ultraviolet survey 

 of the entire celestial sphere. An experiment on board one of NASA's 

 orbiting solar observatories to study solar phenomena is being readied. 



A network of automatic camera stations will make simultaneous 

 observations of meteors over an area of a million square kilometers. 

 This advanced program will provide the basis for a scientific project 

 of collecting meteorites and give vital new data for detailed study of 

 hypervelocity entry, meteoritic physics, and the upper atmosphere. 



At the Observatory the first measurements were made of the radio- 

 active isotopes, argon of atomic mass 37 and 39, produced by cosmic 

 rays on meteorities in space. These measurements contributed to the 

 determination of erosion rates of meteoritic materials of various kinds 

 in space. Radiochemical analyses of recovered satellite materials first 

 proved that solar flares introduce tritium into such material in space 

 as well as producing transmutations of elements. The Observatory 

 participated in a program showing that optical flare stars are also 

 variable in the radio region of the spectrum. 



Other research at the Smithsonian Observatory in the decade 

 included analyses of sophisticated problems in celestial mechanics ; pre- 

 cision linking of the several geodetic networks of the earth; experi- 

 ments involving the origins of life and the possibilities of the extra- 

 terrestrial organisms; studies of comets, meteors, and interplanetary 

 dust; new methods, theories, and conclusions relating to stellar at- 

 mospheres and stellar pulsation; and other astrophysical problems. 



The Division of Radiation and Organisms is a special unit of the 

 Smithsonian Astrophysical Observatory. Research in this unit during 

 the past 10 years has been directed principally toward solving prob- 



