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The Enhanced Thematic Mapper Plus (ETM+) Main Electronics Module (MEM) power supply heat sink temperature is critical to the Landsat-7 mission. It is strongly dependent on the thermal louver design. A lower power supply heat sink temperature increases the reliability of the MEM, and reduces the risk of over heating and thermal shutdown. After the power supply failures in ETM+ instrument thermal vacuum tests #1 and #2, the author performed detailed thermal analyses of the MEM, and proposed to reduce the louver set points by 7°C. At the 1998 Intersociety Energy Conversion Engineering Conference (IECEC), the author presented a paper that included results of thermal analysis of the MEM. It showed that a 7°C reduction of the louver set points could reduce the maximum power supply heat sink temperature in thermal vacuum test and in flight to below 20°C in the cooler outgas mode and in the nominal imaging mode, and has no significant impact on the standby heater duty cycle [1].

The Soft X-Ray Telescope (SXT) is an instrument on the International X-Ray Observatory (IXO). Its flight mirror assembly (FMA) has a single mirror configuration that includes a 3.3 m diameter and 0.93 m tall mirror assembly. It consists of 24 outer modules, 24 middle modules and 12 inner modules. Each module includes more than 200 mirror segments. There are a total of nearly 14, 000 mirror segments. The operating temperature requirement of the SXT FMA is 20°C. The spatial temperature gradient requirement between the FMA modules is ±1°C or smaller. The spatial temperature gradient requirement within a module is ±0.5°C. This paper presents thermal design considerations to meet these stringent thermal requirements.

On Day 97, 2005, a temperature excursion of the Burst Alert Telescope (BAT) loop heat pipe (LHP) #1 compensation chamber (CC) caused this LHP shut down. It had no impact on the Gamma Ray Burst (GRB) detection because LHP #0 was nominal. After LHP #1 was started up and its primary heat controller was disabled on Day 98, both LHPs have been nominal. On Day 337, 2004, the X-Ray Telescope (XRT) thermo-electric cooler (TEC) power supply (PS) suffered a single point failure. The charge-coupled device (CCD) has been cooled by the radiator passively to -50°C or colder most of the time. The CCD temperature meets the main objective of pinpointing GRB afterglow positions. With these anomalies overcome, the Instrument Module (IM) thermal control system (TCS) is nominal during the first 2.5 years in flight.

The Burst Alert Telescope (BAT) instrument of the Swift mission consists of a telescope assembly, a Power Converter Box (PCB), and a pair of Image Processor Electronics (IPE) boxes (a primary and a redundant). The telescope assembly Detector Array thermal control system includes eight constant conductance heat pipes (CCHPs), two loop heat pipes (LHPs), a radiator that has AZ-Tek's AZW-LA-II low solar absorptance white paint, and precision heater controllers that have adjustable set points in flight. The PCB and IPEs have Z93P white paint radiators. Swift was successfully launched into orbit on November 20, 2004. This paper presents a thermal assessment of the BAT instrument thermal control system during the first six months in flight.

The Swift mission Burst Alert Telescope (BAT) Detector Array thermal control system includes two propylene loop heat pipes (LHPs), eight ammonia constant conductance heat pipes (CCHPs), a radiator that has AZ-Tek's AZW-LA-II low alpha white paint, and precision heater controllers that have adjustable set points in flight. The Power Converter Box (PCB) and Image Processor Electronics (IPE) boxes (a primary and a redundant) of the BAT have Z93P white paint radiators. Swift was successfully launched into orbit on November 20, 2004. The spacecraft (S/C) was placed into a safehold mode on August 10, 2007 after an anomaly on inertial reference unit (IRU) #3. It was returned to inertial pointing on August 16 and instrument power up followed. This paper presents a thermal assessment of the BAT instrument thermal control system (TCS) shut down and recovery as a result of the S/C safehold mode. The recovery required starting up the LHPs manually.