SECRETARY'S REPORT 159 



showed that the comet had seven tails. Each consisted of dust ejected 

 in accordance with Wliipple's theory describing tliis process. The 

 larger ejected particles collectively contain more mass than the small. 



Using photographs made by the Baker-Nunn cameras, Daniel 

 Malaise ^^ is obtaining measurements of cometarj- tail activity. This 

 inquiry bears on the interaction of the solar wind with the tails of 

 comets. 



During the summer of 1962 Dr. Pol Swings reviewed the possibili- 

 ties for cometary research provided by the use of rocket vehicles and 

 spacecraft. Observations of infrared and ultraviolet frequencies from 

 orbiting observatories, measurements from a probe flight near a comet, 

 and release of appropriate chemicals from rockets all offer significant 

 opportunity for advancing cometary science. 



Dr. Charles A. ^Vliitney and Dr. Lundquist have initiated laboratory 

 studies of the properties of ices in vacuum to provide several basic 

 parameters for further theoretical descriptions of comets. Prelimi- 

 nary theoretical studies of the nature of comets have indicated the 

 need for several modifications of existing theories. 



Solar observations. — A historic advance in solar observation is the 

 United States' Orbiting Solar Observatory program. To further its 

 long-standing record of pioneering solar observations, Sx^O is playing 

 an active role in this program. 



Dr. Giovanni Fazio was a coexperimenter on the first Orbiting Solar 

 Observatory, launched in March 1962. The experiment provided the 

 first view of a solar flare in the high-energy gamma ray (>100 Mev) 

 portion of the electromagnetic spectrum. Within the sensitivity of 

 the detector, there was no evidence for gamma radiation. Data re- 

 duction ^° is continuing, and theoretical calculations on the sun's 

 production of gamma rays have been made. 



Dr. Leo Goldberg is directing a Harvard University project " to 

 prepare instrumentation for the second Orbiting Solar Observatory, 

 scheduled to be launched during the fall of 1963. The instrument is 

 designed both to make scans of the solar spectrum and to obtain mono- 

 chromatic solar images in the wavelength range 500-1500 A. Both 

 the prototype and the flight models of the satellite instrimient have 

 been delivered for integration into the spacecraft. A considerable 

 number of the routine environmental tests have been passed. 



Design work has already begun on an improved model of the scan- 

 ning spectrometer-spectroheliograph, which has been allocated space 

 on board the fourth Orbiting Solar Observatory. Design work is 

 also proceeding on a spectrometer that will operate in the short wave- 

 lengths from 100-600 k}^ 



See footnotes on p. 164. 



