88 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



Dr. Luigi G. Jaccliia's studies of atmospheric drag on artificial 

 satellites have already contributed profoundly to our knowledge of 

 atmospheric densities above the height of 200 km. His conclusions as 

 to variations of the atmosphere with time, solar activity, and geo- 

 graphic position, as well as his determinations of the atmospheric 

 density profile, have received general international acceptance. He 

 will continue to explore the problems of solar-terrestrial effects. 



Dr. G. Colombo has made a study of the motion of Explorer IV 

 (Satellite 1958 Epsilon) around its center of mass, as inferred from 

 observations of several kinds, and the possible causes of the strong 

 variations of the elements of the tangential precessional motion. Al- 

 though a precise knowledge of the residual magnetization of the body 

 of the satellite and the ferromagnetic components of the payload is 

 needed for an exact computation, he draws attention to the unexpected 

 pronounced effect of the interaction between the earth's magnetic field 

 and the shell (of stainless steel) of the satellite. 



Dr. Leo Goldberg, with Dr. William Liller, is directing the design 

 and construction of two ultraviolet scanning spectrometers for flight 

 in the S-17 Satellite within the framework of the program of Orbit- 

 ing Solar Observatories of the National Aeronautics and Space 

 Administration. The combined spectral range of the spectrometers 

 will be 75 A. to 1500 A. and the resolving power will vary between 0.3 

 A. at the longer wavelengths and 1.0 A. at the shortest wavelengths. 

 Design of the spectrometers is now in the final stages. Calibration 

 and testing of the instrument packages will be carried out in a new 

 laboratory recently installed in the Space Science Building. 



The work of the laboratory will also be expanded in the fall to 

 include a broad program of basic research on the vacuum ultraviolet 

 radiation of atoms and molecules of astrophysical importance with 

 one- and two-meter vacuum spectrographs and a shock tube and flash 

 tube as sources. The scanning spectrometers are scheduled for rocket 

 flights at the end of 1961 and for flight aboard the S-17 Satellite dur- 

 ing the last quarter of 1962. 



Dr. Goldberg has been engaged in a study and survey of astro- 

 nomical experiments that may be performed with satellite vehicles. 

 The conclusions of the survey have been published in two chapters 

 of "Science in Space" in collaboration with Dr. E. E. Dyer, Jr. 



The Director and Dr. Robert J. Davis, astrophysicist in charge, 

 together with other Observatory scientists, have progressed with the 

 planning and development of the "Celescope" project, a group of 

 astronomical telescopes to be carried in sounding rockets and later or- 

 bited in artificial earth satellites. Specifications for the satellite 

 payload (telescope system) have been prepared, and final negotiation 

 for the manufacture of the instruments is being awaited. With the 

 aid of television images in three colors and slitless spectrograms of the 



