Final work on the Vanguard instrument

Even though there was tremendous excitement about the Soviet Sputnik announce­ment at the conference, I still had a work session scheduled at NRL. Their engineers and I pushed ahead resolutely to complete that work, beginning immediately following the conference closure at noon on Saturday, 5 October.

The first order of business was to test and calibrate the radio frequency portions of the complete system, both the satellite portions independently, and then with the ground receiving and transmitting equipment. Martin (Marty) J. Votaw and Roger Easton, the Vanguard senior engineers for those components, made the measurements and adjusted the design as needed. For that purpose, we mounted the instrument package in the NRL prototype satellite shell. Final tailoring of the wiring harness to the antennas adjusted the phasing of the signals to produce the correct antenna radiation pattern. Those tests also revealed the need for an additional radio frequency shield between the receiver and transmitter circuit decks. After several days of fitting and tuning, our measurements showed that the telemetry transmitter, command receiver, antennas, and interconnecting harness were all operating properly as a system.

Next, we began tests to check the performance of the satellite while it was operating in concert with the prototype ground station. Runs with varying amounts of signal attenuation gave us confidence that the space and ground components should operate together over an orbit-to-ground range of up to several thousand miles.

As a final test, we had planned to fly the instrument package via helicopter over the first operational Minitrack receiving station located on the shore of the Chesapeake Bay at Blossom Point, Maryland. Delays in getting the Blossom Point station fully operational, compounded by their scramble to modify the station to receive the signal from the newly launched Soviet satellite, forced a postponement. In spite of the incomplete testing, we did develop reasonable confidence that the space-to-ground link would perform as intended.

The radio frequency tests were to be followed by a (it was hoped final) set of design-level vibration and acceleration tests. However, those tests, planned for 9 and 10 October, could not be undertaken on schedule due to breakdowns in the test equipment, and they were rescheduled for a later time.

Before they could be run, our instrument was shifted to the army’s Jupiter C program.

OPENING SPACE RESEARCH

I finally returned to Iowa City on Wednesday, 16 October, 12 days after the Sputnik launch. During the rest of October, I scrambled to try to catch up with my university course work and to attend to a few lingering details of the electronic circuit design and package fabrication. My laboratory notebook entry for 29 October stated quite simply, “Completed test unit.”28 Although a slight overstatement, that point did mark the end of all work on the Vanguard version of the instrument, and my full attention shifted to adapting the instrument to the Army’s Jupiter C vehicle.

A final progress report to our granting agency in October listed a few minor items to be completed and mentioned that the first of the magnesium satellite shells was due to be delivered by the fabricator to NRL in November.29 That final report also listed the instrument package weight as just under 13.0 pounds, which, when added to the weight of the satellite structure and other components, made the total satellite weight two to three ounces less than the 21.5 pounds that had been allocated.