As its name implies, the Temperature Control Subsystem is responsible for maintaining the temperature of the spacecraft within an acceptable range. Cassini's circuitous route to Saturn will expose it to extreme variations in its thermal environment. When flying by Venus, the solar heating will be nearly three times greater than it is at the Earth's distance from the sun. At the other extreme, when Cassini is at Saturn, solar irradiance will be nearly 100 times less than at 1 AU and extreme cold becomes a concern.
Temperature on the Cassini-Huygens spacecraft is maintained through a combination of special hardware and special handling procedures. For example, during the cruise to Saturn, the high-gain antenna is oriented toward the sun when the spacecraft to Sun range is less than 2.7 AU to shield most of the other spacecraft components. Special temperature control hardware includes thermal blankets, shades, thermal shields, louvers and heaters. Thermal blankets provide insulation. Thermal shields shade components from the Sun. Louvres dissipate heat from electronics bays. Each instrument has an electrical heater, but they are used sparingly, to bring equipment up to operating temperature. However, because of clever design techniques, few other electrical heaters are needed, as waste heat from the Radioisotope Thermoelectric Generators (RTGs) is used to heat electronic equipment.
Last Update: 10 Jun 2004