Space Test Program-Houston 4-Active Thermal Tile (STP-H4-ATT) - 12.03.13
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Space Test Program-Houston 4-Active Thermal Tile (STP-H4-ATT) investigates variable conductance thermal tiles that serve as a quick-insert thermal management device for satellite components. The tiles contain thermoelectric devices capable of operating in heating, cooling and neutral or “off” modes. The tiles improve satellites’ thermal control systems, which protect instruments used to collect data and communicate with Earth.
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OpNom: STP-H4Principal Investigator(s)
Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
National Laboratory - Department of Defense (NL-DoD)Research Benefits
Information PendingISS Expedition Duration:
March 2013 - March 2015Expeditions Assigned
35/36,37/38,39/40,41/42Previous ISS Missions
- Space Test Program-Houston 4-Active Thermal Tile (STP-H4-ATT) improves satellite thermal control systems which are important for providing communication and navigation information to terrestrial systems. Improved thermal control reduces satellite mass and cost.
- STP-H4-ATT measures the on-orbit performance of a variable conductance interface concept that is based on thermo-electric devices. Various heat loads are applied with heaters while STP-H4-ATT is in various operational configurations and the resulting temperature distribution will be measured. From these temperature measurements, the cooling performance provided by STP-H4-ATT is calculated.
- This research will be used to develop a fully operational system for future satellite missions as well as provide verification and validation of the thermal model used for developing STP-H4-ATT hardware.
The Active Thermal Tile (ATT) is a variable conductance interface that uses a thermoelectric device (TED) to modulate heat transfer between two interfaces – typically between a component and the spacecraft bus. The TED operates in three modes: cooling, heating, and off (which is the low conductance insulating mode). The Space Test Program-Houston 4-Active Thermal Tile (STP-H4-ATT) experiment measures the initial on-orbit performance of an ATT string consisting of four tiles to determine performance relative to ground testing and to anchor the thermal model. In addition, a subset of the initial testing is performed periodically during the 12 months of on-orbit operations to measure any degradation over time caused by the space environment. STP-H4-ATT remains on-board the ISS in low earth orbit for approximately 12 months to access the performance of the materials, the system, and the control algorithms. The primary quantities of interest to be determined are the effective conductance in the high conductance cooling state, effective conductance in the low conductance state, and the coefficient of performance (COP) in the cooling and heating states. The quantities are determined using temperature measurements at the boundary conditions, the power draw from the TEDs, and input heater power. The TED current, heater power, and boundary temperatures are varied to map the thermal performance of the STP-H4-ATT experiment.
STP-H4-ATT improves thermal control systems for satellites, which can experience dramatic temperature fluctuations between sun-facing and space-facing sides. Regulating heat protects satellite instruments that gather data and communicate with Earth and other spacecraft, providing communication and navigation capabilities.
STP-H4-ATT improves thermal control systems, which are used in a wide range of consumer and industry applications. For example, variable conductance thermal tiles can be used to regulate the temperature of luxury automobile seats.
STP-H4-ATT operates continuously while attached to the ISS. During the 12 months on-orbit, more than 300 cases are investigated to measure the overall on-orbit performance envelop of the hardware and to measure any degradation over the 12 month lifetime caused by the combined effects environment. Each case requires between 4 and 24 hours depending on the time to reach thermal steady state conditions.Operational Protocols
STP-H4-ATT operates continuously while attached to the ISS. During the 12 months on-orbit, more than 300 cases are investigated to measure the overall on-orbit performance envelop of the hardware and to measure any degradation over the 12 month lifetime caused by the combined effects environment. Each case requires between 4 and 24 hours depending on the time to reach thermal steady state conditions.
Computer generated image of STP-H4.
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