TABLE OF CONTENTS Heating sources are present throughout the life of a satellite, but because operational time in orbit is by far the longest, most of thermal engineering is expended on ensuring long-term temperature stability in space. Of course, this is not to say that the evaluation of other phases in a satellite's history are less important.
The nature of heating and the methods for dealing with it are defined in terms of the source and the surrounding environment. These can be divided broadly into ground, vacuum testing, launch, and space. On the ground, heating is due mostly to equipment dissipation and the conditions of surrounding air. Direct or indirect solar effects must also be considered when the satellite is not sheltered. Vacuum testing eliminates the interaction with air but must contend with the presence of gravity and the limitations of vacuum chambers to simulate the true thermal environment in space. During launch, the effects include exposure to sunlight and air molecular friction. Finally, heating in space is considered due mainly to satellite equipment dissipation and radiation from the sun and planets. Parasitic sources affecting cryogenics, or nuclear power, superhigh rf generation, and other specialized systems are treated by following essentially the same principles but with correspondingly applicable conditions.
While on the ground in air, the desired temperatures are created by air conditioning, a process that continues through launch operations until shortly before liftoff. Heat removal takes place by exchange with either still or flowing cool air (sometimes...
