Component Design, Construction and Evaluation for Satellites

The importance of component reliability in the production of a successful electronic equipment of the complexity and with the reliability requirements of the Telstar satellite is well appreciated. Small systems and those of less complexity can be designed and built with special care, at reasonable cost, to have long life; large systems are subject to the laws of large numbers, which increase the probability of the malfunction1665 1070 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 190.3 ing of at least one component part. Normal maintenance of large earthbound systems may be economical, however, and system performance may be acceptable if malfunctions are not too frequent. In an orbiting satellite, on the other hand, the first failure must be at sufficiently great time to provide an economical system, and the component failures must therefore be sufficiently distant in time, or at a sufficiently low rate, to allow a practical design. This does not ignore the requirement that the circuit and equipment designs use the component characteristics to best advantage, and also protect themselves as much as possible against the probable modes of component failure. Considerable experience has been built up in the Bell System on the use of parts of high reliability, a most easily recognized example being the long submarine telephone cable systems which at this date have had no failures in over 109 passive component hours and 5 X 107 electron tube hours of service. The submarine cable repeaters, however, use specially designed and manufactured electron tubes and passive components.