Remembering Gemini 3

by John Lambie

Gemini Titan 3 (GT3) was the first manned mission supported by the new Carnarvon Tracking Station in Western Australia.

My duties at CRO was to maintain the model 28 Teletype system, both the machines connected to the NASACOM communications lines, and the machines at remote sites as monitors. A critical machine was the ASR at Monte Sala’s Digital Command System. This machine was equipped with special code reading contacts to convert the incoming line signal (in serial five unit code), to a parallel word for direct inputting to the DCS.

Prior to the mission date in March 1965 I had routinely checked my annual maintenance record dates, and also helped the Operator Staff carry out preparatory operational checks to ensure adequate paper rolls and paper tape were fitted, and good ink ribbons to ensure good printing. Machines fitted with five ply NCR paper( no carbon required) required the striking pressure on the printing hammer to be adjusted for readable type on the bottom copies.

During missions administration traffic was kept to an absolute minimum, as operational messages, some with selective calling, had priority.
On the full duplex lines the outgoing lines were for real-time radar data traffic to the Goddard Space Flight Centre, in Maryland, Near Washington.

I was completely surprised and elated when Arch Durie (the Comms Supervisor) requested I be present on-site during the countdown and mission period for GT3. A request to the PMG administration in Geraldton was a formality and I attended to the site several hours before the scheduled liftoff of Grissom and Young on the scheduled three orbit mission.

During the count-down period I was given a scripted document title “Detailed System Test 108” This was a network wide test required to check and exercise the TTY Systems. Each test had to be completed thoroughly and signed off by me, as the operator. A “Green” or “Not Green” condition had to be ticked off and notified.

A “Not Green” condition had to be worked on until the status of “Green” was obtained.

Test equipment was used to check for signal bias. At the machine, the motor speed of the series-wound motor was checked. This was done with a special tuning fork with shutter tines. The fork was struck and viewed with the eye at strobe makings on the motor governor housing. If the pattern was seen to revolve, either clock or anti clock, the motor speed would be adjusted until a steady pattern was observed.

Then the range finder lever on the machine selector unit was moved to “advance” until distortion occurred (evident as wrong characters on a test message), the range finder scale number was noted. The range finder lever was then retarded until again distortion occurred. The range number was again noted. The two numbers were added and divided by two to set the signal selector to the optimum.

The Detailed System Test (DST108) was done once, another scripted test, the “Brief System Test 108”. (BST108) was done hourly. A much simpler test.

During the mission everyone was on their toes for the 10-15 minutes while CRO was acquiring signal and tracking. During the 90 minutes between passes things were quieter and I personally would sit and read a magazine or two, Sometimes “Scientific American”. At other times boredom easily set in as we were not aware what was happening?

I would occasionally walk down to the guys who had the receivers monitoring WWV time standard and they would have a radio tuned to “Voice of America” and we would hear a “blow by blow” description from Walter Cronkite.

Months later when GT4 was scheduled, a much longer mission, which together with simulations went on for 21 days.