Passive Thermal Control |
A passive thermal control system helps maintain the temperature of the orbiter spacecraft, systems and components within their temperature limits. This system uses available orbiter heat sources and heat sinks supplemented by insulation blankets, thermal coatings and thermal isolation methods. Heaters are provided on components and systems in areas where passive thermal control techniques are not adequate. (The heaters are described under the various systems.)
The insulation blankets are of two basic types: fibrous bulk and multilayer. The bulk blankets are fibrous materials with a density of 2 pounds per cubic foot and a sewn cover of reinforced acrylic film Kapton. The cover material has 13,500 holes per square foot for venting. Acrylic film tape is used for cutouts, patching and reinforcements. Tufts throughout the blankets minimize billowing during venting.
The multilayer blankets are constructed of alternate layers of perforated acrylic film Kapton reflectors and Dacron net separators. There are 16 reflector layers in all, the two cover halves counting as two layers. Covers, tufting and acrylic film tape are similar to that used for the bulk blankets.
The contractors are Hi-Temp Insulation Inc., Camarillo, Calif. (fibrous insulation); Scheldahl, Northfield, Minn. (cover materials and inner layers); Apex Mills, Los Angeles, Calif. (separators).