The ever-increasing processing power of spacecraft and satellites puts a tremendous demand on the thermal control subsystem (TCS) to acquire, transport, and reject large amounts of heat. Consequently, the radiator surface needed to reject the anticipated highest amount of heat become large. The TCS gets very cold in the nominal or part-load operations in the cold spacecraft attitudes. Temperature control of the on-board payloads is essential for the optimal performance and long lifetime of the equipment. Electrical power is often expended to maintain the payloads above the temperature limit, conceivably overwhelming the power subsystem. The radiator temperatures may drop below the freezing point of the working fluid in the worst-case survival mode. The existing âdirect condensationâ radiator technology does not allow the fluid to freeze, precluding the best available refrigerant â Ammonia â to be used for room-temperature applications. The proposed Passive Variable Heat Rejection Freeze-Tolerant Direct Condensation Deployable Radiator offers an innovative method of (i) autoregulating the heat rejection just enough to condense the vapor load back to saturated liquid, (ii) allowing the heat transport loop to operate while the radiator fluid is frozen, and (iii) gracefully thawing out the radiator and return the loop to normal operation Potential NASA Applications (Limit 1500 characters, approximately 150 words): NASA have developed thermal technologies to meet the ever-increasing thermal requirements of space thermal control systems (TCS). The current state-of-the-art heat acquisition/transport/rejection system has reached the upper limit of its capacity. New more capable technologies have been developed in the acquisition and transport of heat but the rejection aspect still remains unchanged. In particular, the fluid in the radiator is not allowed to freeze. The proposed radiator concept will resolve the issue to increase the system capacity. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): The commercial satellite market has been increasing at a very fast rate from the demands of telecommunications and entertainment industries. The heat dissipation rises. The thermal technologies must be utilized in the most efficient way to maximize the heat transport capacity. The proposed radiator concept allows the thermal subsystems to provide optimal conditions for the onboard payloads Dura
