satellite, TRANSIT 3-B, had perigee so low that it had a life of 
only 36 days and it reentered the atmosphere and was consumed on 
March 30. There have also been a few equipment failures in the 
satellites themselves. A temperature sensitive switch, included 
in TRANSIT 1-B to protect the storage battery from overcharge, 
opened improperly and permanently on or about July 11, 1960, and 
the satellite ceased radiating due to loss of power. Thus TRANSIT 
1-B had a useful radiating life of 89 days. The same switch mal- 
functioned in TRANSIT 2-A. [In this case a commarid by-pass of the 
switch had been incorporated and was actuated to prolong the life 
of the satellite. However, bypassing this switch removed the over- 
charge protection which was the reason for incorporating the switch 
and the storage battery was destroyed by overcharge during the 
period October 28 to November 14, 1960, while the satellite was in 
the sunlight at all times and correspondingly receiving maximum 
power from its solar cells. Since the loss of the storage battery 
the TRANSIT 2-A radiates only when it is in sunlight, receiving 
power directly from the solar cells. With this intermittent opera- 
tion the stability of the oscillators is, of course, not up to the 
level that obtained during the period of proper, full-time operation. 
TRANSIT 3-B operated fully throughout its short life. 
In spite of these various limitations, it has been 
possible, with the three satellites placed in orbit to date, to 
demonstrate rather remarkable progress toward overcoming the major 
technical obstacles that lay in the path of establishing an opera- 
tional system. In particular, there are no longer any questions 
about the feasibility of the operational concept and it is now 
possible to specify a detailed design with confidence that it will 
meet the requirements. 
In what follows, the various areas that were expected 
to provide technical difficulties will be discussed and the state 
of progress toward their solution will be described. 
95 
