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).
