330-PSA-286-60 (USN 710826):  Heart of a Satellite.  This small vacuum-protected heart of the Transit 3-A navigational satellite is an ultrastable crystal oscillator which pulses at a rate of several million beats a second.  It’s being held here by J. Barry Oakes, the physicist of the Applied Physics Laboratory of the Johns Hopkins University, who developed it.  The crystal’s sure, unchanging oscillations provide the signals on which Doppler measurements are made to enable Navy scientists to determine with precision the position of the satellite.  Here, the oscillator or crystal is encased in a special three-cylinder high-vacuum flask.  The flask bars nearly all temperature influence on the oscillator thus insuring a stable signal – vital if the Transit system is to operate. Photograph released November 11, 1960.  (9/15/15).
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/127906254@N06">National Museum of the U.S. Navy</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/127906254@N06/21464583995/">330-PSA-286-60 (USN 710826)</a>