This system for the distribution of data by means of a satellite 
link was incorporated, for the first time, in the short-lived 
TRANSIT 3-B and operated perfectly throughout its life. 
4. Time Synchronization 
Since the time at which orbit parameters are trans- 
mitted is controlled by a satellite clock based on the same stable 
oscillator that controls the two basic frequencies, it is clear that 
the time of reception of orbit parameters can be used as a time 
signal by the ground equipment. This makes the TRANSIT system com- 
pletely self contained and independent of any other time source such 
as WWV. Actually, because of the short, well defined transmission 
path for the TRANSIT line-of-sight frequencies and the excellent 
knowledge of satellite position, the time signals available from 
TRANSIT will be more accurate than those available from WWV in most 
areas of the world. In fact, a precision of 100 microseconds should 
be readily available. A system has been developed for including along 
with the orbit parameter transmission a special word ("Barker" word) 
which serves the purposes of a start of message and time synchro- 
nization signal. This system also was successfully tested in 
TRANSIT 3-B. 
Ove Thermal and Power Balances 
One technical problem that proved quite serious in the 
design of early satellites was to achieve the proper control of 
satellite temperature and input power under the varying conditions 
that occur in orbit. If one considers polar satellites, it is 
clear that when the orbital plane is roughly at right angles to 
the earth-sun line then the satellite will be exposed to sunlight 
throughout its orbit. At the other extreme, if the sun lies in 
the orbital plane the satellite will be in the earth's shadow for 
a considerable portion (about 40% for the satellites at altitudes 
intended for TRANSIT) of each orbit. Since for a polar satellite 
the orbital plane remains fixed in inertial space while the earth- 
sun line rotates in inertial space once a year, it is clear that 
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