FUEL TANK NITROGEN TANK JET VANE ACTUATOR (ONE OF FOUR) THRUST CHAMBER
Hydrazine, a monopropellant, requires a starting ignition for proper combustion. In the Mariner system, nitrogen tetroxide starting or “kindling” fluid was injected into the propellant tank by a pressurized cartridge. Aluminum oxide pellets in the tank acted as catalysts to control the speed of combustion of the hydrazine. The burning of the hydrazine was stopped when the flow of nitrogen gas was halted, also by explosively activated valves.
TEMPERATURE CONTROL
Mariner’s 129 days in space presented some unique problems in temperature control. Engineers were faced with the necessity of achieving some form of thermal balance so that Mariner would become neither too hot nor too cold in the hostile environment of space.
The spacecraft’s temperature control system was made as thermally self-sufficient as possible. Paint patterns, aluminum sheet, thin gold plating, and polished aluminum surfaces reflected and absorbed the proper amount of heat necessary to keep the spacecraft and its subsystems at the proper operating temperatures.
Thermal shields were used to protect the basic hexagon components. The upper shield, constructed of aluminized plastic on a fiberglass panel, protected the top of the basic structure and was designed for maximum immunity to ultraviolet radiation. The lower shield was installed below the hexagon; it was made of aluminum plastic faced with aluminum foil where it was exposed to the blast of the midcourse rocket engine exhaust.
Methods used to control the temperature of the Mariner spacecraft in flight.
CHROMATE CONVERSION COATING UPPER THERMAL SHIELD POLISHED ALUMINUM LOUVERS GOLD PLATE BLACK PAINT LOWER THERMAL SHIELD WHITE PAINT
The six electronics cases on the hexagon structure were variously treated, depending upon the power of the components contained in each. Those of high power were coated with a good radiating surface of white paint; assemblies of low power were provided with polished aluminum shields to minimize the heat loss.