SECRETARY'S REPORT 155 



Dr. Carleton and his associates are conducting laboratory experi- 

 ments on ion-molecule and molecule-molecule collisions in the range 

 of 200-2,000 ev energy.* One application of this work is a calcula- 

 tion of the amount of excitation and ionization produced by micro- 

 meteorites too small to be observed individually on their entry into 

 the atmosphere. In that connection they have considered what limits 

 can be set on the rate of influx of such micrometeorites, concluding 

 that such effects are negligible. 



Statistical analyses of precisely reduced photographic meteor data 

 from Super-Schmidt cameras are being made by Dr. Jacchia, Dr. 

 Verniani, and Mr. Briggs. Their aim is to publish the wealth of in- 

 formation, obtained through several years of meteor photography 

 and painstaking reductions, concerning the interaction between the 

 meteor body and the atmosphere. In particular, they can determine 

 the mass, luminous efficiency, and tensile strength of a meteor body 

 more accurately than has been possible before. 



In study of the spectra of meteors,^ Dr. Cook is working with Dr. 

 T. Halliday of the Dominion Observatory, Ottawa, and Dr. P. M. 

 Millman of the National Research Council of Canada. Currently a 

 quantitative spectral analysis of Perseid spectra is under way. 



Work on daily motion of the radiant of the Quadrantid meteor 

 stream was begun. Dr. Frances Wright will continue this project 

 until all photographic film on hand has been measured, and the motion 

 of the radiant is determined. This study will yield further knowledge 

 of the nature of the Quadrantid meteor streams. 



Dr. McCrosky has continued a cooperative research effort with 

 Harvard College Observatory, U.S. Air Force,^ MIT Lincoln Lab- 

 oratory,^ and NASA, in which various successful attempts have been 

 made to inject into the upper atmosphere, at meteoric velocities, bodies 

 of sufficient and known size to reproduce the meteor phenomena. 



This research has led to improved values of the luminous efficiency 

 of ablating hypervelocity bodies entering the atmosphere and of the 

 masses and densities of meteoroids. 



The Radio Meteor Project ^ is a joint enterprise of the Smithsonian 

 Astrophysical Observatory and Harvard University. The project has 

 operated a multistation radar system at Plavana, 111., at a peak trans- 

 mitter power of 4 megawatts. Meteors have been detected down to a 

 limiting magnitude of +12 on the visual scale. Dr. Hawkins is the 

 scientist in charge of this project. 



To determine the atmospheric trajectory of the meteoroid and its 

 orbit in interplanetary space. Dr. Hawkins and Dr. Southworth have 

 analyzed the radar echoes. Drs. Hawkins and Bertil-Anders Lindblad 

 liave found that there is a definite difference in the populations of large 



See footnotes on p. 164. 



