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Loop Heat Pipe (LHP) technology has advanced to the point that LHPs are baselined for thermal control systems in many spacecraft applications. These applications typically utilize a loop heat pipe with a single evaporator. However, many emerging applications involve heat sources with large thermal footprints, or multiple heat sources that would be better served by LHPs with multiple evaporators. Dual evaporator LHPs with separate reservoirs for each evaporator have been successfully developed, but the volume and weight of such systems become impractical as the number of the evaporators increase to more than three or four. Other investigators have proposed systems containing several evaporators that are coupled to a common reservoir with a conduit to contain a capillary link (secondary wick). This approach places several restrictions on the relative location of the evaporators due to the limitation of the capillary link.

Loop Heat Pipe (LHP) technology has advanced to the point that LHPs are baselined for thermal control systems in spacecraft applications. Many of the applications also require redundant systems to address reliability concerns. In the redundant design, two LHPs are plumbed in parallel to the same heat source and sink. The LHPs are totally separate, and each is designed to fully accommodate the total heat load at the source if the other LHP should fail. Due to the self-regulating nature of an LHP, questions have been raised regarding the expected behavior of two LHPs operating in parallel between the same source and sink, particularly their ability to self-start and equally share the heat load. To demonstrate the application of LHPs in a redundant system, two totally independent LHPs, each with the same condenser plate and heat source, were fabricated and tested.

Loop Heat Pipe (LHP) technology has advanced to the point that LHPs are baselined for thermal control systems in many spacecraft applications. These applications typically utilize a loop heat pipe with a single evaporator. However, many emerging applications involve heat sources with large thermal footprints, or multiple heat sources that would be better served by LHPs with multiple evaporators. Other investigators have proposed systems containing several evaporators that are coupled to a common reservoir; however, this approach places severe restrictions on the relative locations of the evaporators. This paper describes a multiple evaporator loop heat pipe, with a separate reservoir for each evaporator, which can accommodate payloads with large or spatially separated heat sources.

Capillary Pumped Loops (CPLs) have been under development for almost two decades and are emerging as a design solution for many spacecraft thermal control systems. Three Capillary Pumped Heat Transport Systems (CPHTS) using CPL technology have been selected for accommodating the two Earth Observing System (EOS-AM) instruments that require advanced waste heat dissipation. The Capillary Pumped Loop Flight Experiment (CAPL-2) [Ref 7], which was carried on board STS-69, successfully demonstrated an EOS-like capillary system utilizing a prototyped starter pump cold plate (SCP). The CAPL-2 SCP is almost identical to the EOS-AM configuration and was designed, built, and demonstrated to overcome the start-up difficulty under fully flooded conditions. The SCP was rigorous ground tested as part of a simulated EOS-AM / CAPL-2 capillary loop, and the SCP successfully met or surpassed all of its performance requirements.

The COMmercial Experiment Transporter (COMET) is a satellite will launch aboard the Conestoga rocket. COMET provides the United States Commercial research and development community with a dependable and economical means to access space. The COMET program is defined and funded by the NASA Centers for the Commercial Development of Space (CCDS). The Center of Space Transportation and Applied Research (CSTAR) was given the authority to establish and implement the COMET program. The COMET Service Module is designed, integrated and tested by Defense Systems Incorporated for Westinghouse Commercial Space. The Capillary Pumped Loop (CPL) was integrated into the Service Module by OAO Corporation for Defense Systems Incorporated. The Service Module's primary function is to carry payloads to space, providing them with utilities such as a tightly controlled thermal environment, electrical power, attitude control, data management, and communications while in orbit.

This paper presents the COMmercial Experiment Transporter (COMET) Service Module thermal control system design using a Capillary Pumped Loop (CPL). The COMET satellite is scheduled for launch in early 1993 aboard the Conestoga rocket. COMET provides the United States commercial research and development community with a dependable and economical means to access space. The COMET program is defined and funded by the NASA Centers for the Commercial Development of Space (CCDS). The Center for Space Transportation and Applied Research (CSTAR) was given the authority to establish and implement the COMET Program. COMET is designed to carry experiments to the micro-gravity of space and return one of two modules back to Earth. COMET provides basic utilities such as electric power, a tightly controlled thermal environment, attitude control, data management and communications while in orbit. COMET is a two part Free Flyer, which will carry experiments into a low Earth orbit.