SATELLITE-TRACKING PROGRAJM — HAYES 277 



published by Viking Press the same year. Gathered and edited by 

 Cornelius Ryan of the Collier's staff and written for a popular au- 

 dience, the papers included "The Heavens Open," by Whipple ; "Prel- 

 ude to Space Travel," by von Braun; "This Side of Infinity," by 

 Kaplan ; and "A Station in Space," by Willy Ley. The last described 

 in some considerable detail a manned, wheel-shaped satellite 250 feet 

 in diameter, circling the earth every 2 hours at a mean altitude of 

 1,075 miles. The station would serve as "a superb observation post" 

 from which technicians could inspect every ocean, continent, country, 

 and city on earth, and study the universe without the optical and radio 

 interference of the atmosphere. Interestingly enough, no mention was 

 made of the possibility of tracking the station from ground observa- 

 tories. Indeed, the idea was quite the opposite : observers in the space 

 station would "track" the earth and would determine, for example, the 

 shape of the earth by precise photographs of the edge of moonlight as 

 it passed across the face of our planet. 

 Dr. Whipple did, however, include in his chapter the following : 



Predicting the position and motion of the space station itself will be one of 

 the most difficult problems ever encountered in celestial mechanics, or the 

 science of predicting the positions of astronomical objects. The earth's doorknob 

 shape, with a bulge of several miles at the equator, combines with the changing 

 direction of the moon's attraction to alter slightly but continuously the nearly 

 circular orbit of the space station. Until recently, the calculation of such an 

 orbit would have taken a good computer a considerable number of hours. But the 

 orbit of the space station will change by an infinitesimal amount in the short 

 period of each 2-hour swing. Therefore, unless the computer can calculate this 

 new orbit in less than the 2 hours necessary for the space station to make one 

 journey around the earth, it is obvious that his calculations can never keep 

 abreast of the space station, let alone predict its position in the future. 



The answer to the computing problem lies, of course, in the huge "electronic 

 brain" calculation machines which we have today. Their use on the ground will 

 be absolutely essential in plotting the motion of the space station. Following 

 this man-made island in the sky continuously and precisely, these electronic 

 machines will be able to make exact calculations with much greater rapidity 

 than the speed of the space station in its 2-hour journeys around the earth. 



While this space-station project, although feasible, could not have 

 been completed in less than 15 years, its specifications were based on 

 research that was to help make possible the lamichmg of our first 

 satellite. Explorer I, in 1958. 



PROJECT ORBITER 



In June 1957 what was to become known as Project Orbiter was 

 defined by a group of scientists assembled in Washington. Attending 

 this meeting were Comdr. George W. Hoover, Office of Naval Re- 

 search; Wernher von Braim; Frederick C. Durant, president of the 

 International Astronautical Federation ; Fred Singer of the Univer- 

 sity of Maryland ; Fred L. Whipple of Harvard ; David Young of the 



