Within the white aluminum-oxide outer shell of the satellite is crammed
a complicated array of electronic equipment. Surprisingly, most of this
gear has to do not with Telstar’s prime function—communications—but with
its command and telemetry systems. The reason is that the satellite is
an experimental device, not just a spectacular way to relay television
programs. Altogether, the satellite’s various electronic circuits
contain more than a thousand transistors and almost 1500 semiconductor
diodes, plus a single electron tube—a traveling-wave tube used in the
communications amplifier.
The satellite itself has a magnesium frame that is covered with aluminum
panels. All its electronic components are inside a aluminum canister, 20
inches in diameter, attached to the interior frame by special nylon
lacings that reduced vibration inside the canister during launch. When
all the components and subassemblies had been carefully put in place and
thoroughly tested, the canister was filled with a liquid foam called
polyurethane. This material hardens into a very light and rigid solid,
completely enveloping the equipment and protecting it from damage and
vibration. After the canister was solidly foamed, metal domes were
welded onto the ends, and it was enclosed in a many-layered blanket of
aluminum-coated Mylar (the same material used in the Echo balloon). To
keep its temperature properly controlled, shutters on the canister’s two
ends are operated by bellows.
The satellite power system includes more than just solar cells. When
operating at full capacity, the satellite’s equipment needs more energy
than the 3600 solar cells can provide at one time. So Telstar also uses
a storage battery made up of 19 rechargeable nickel-cadmium cells
designed for this special purpose. These ensure that the satellite has a
continuous and sufficient supply of power, even when all equipment is in
operation or when the satellite is passing through the earth’s shadow.
[Illustration: _After all electrical tests had been made on the
satellite’s components, the electronics canister was filled with
liquid polyurethane foam, using this specially developed foam
machine_]
[Illustration: _The giant horn antenna at Andover, Maine_]