Smithsonian Report, 1960 — Green and Pettengill 



Plate 3 



1. This small crystal forms the heai't of the maser built by Robert II. Kinvsion for ampli- 

 fying radar echoes from Venus. Tlie paramagnetic crystal accepts power delivered at 

 5,400 megacycles through the entry at the right, and uses it to augment the weak 440- 

 megacycle signal that flows in the loop of wire around the crystal. 



2. The CG-24 computer seen here works directly from the output of the Millstone Hill 

 radar in tracking artificial satellites, and to sum up Venus echoes. It was used to make 

 the lunar map in figure 4. 



