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Two of Orbital's larger louver units (42 blades each) mounted on the Multimission Modular Spacecraft (MMS) for use on the Upper Atmosphere Research Satellite S27.97 causing the blades to rotate to a closed position so that heat from the baseplate/radiator can be reflected by the highly polished blade surfaces. The opening and closing of the louver blades continues throughout the orbital flight to maintain thermal control within a narrow temperature band. Furthermore, since a pair of louver blades is driven by independent sensors, local thermal control across the emitting base is afforded. Louver assemblies have been designed to operate between fully-closed and opened positions in either a 10°C or 18°C temperature differential. They are capable of operation within an environmental range of -85° C (-120° F) to +120° C (+250° F), with a minimum operation capability (open-to-close/close-to-open) of well over 30,000 cycles with no degradation in performance. Orbital's thermal control louvers are lightweight, self- contained, consume absolutely no power, and can be adjusted to maintain temperature control over wide thermal spectrums. They have an extensive space flight heritage in many tailored geometric configurations. Louvers having specific configurations and operational parameters can be developed to meet mission unique requirements. Thermal louvers have gained a wide acceptance in the Aerospace industry as highly-efficient devices for controlling the temperature of a satellite. Orbital's first louvers were flown in 1965. Since then, more than 500 Orbital louver units have flown on numerous satellites, including NIMBUS-4, 5, 6 & 7; Landsat-2, 3, 4 & 5; OAO A2 & A4; ATS-6, Viking-1 & 2; Voyager-1 & 2; NAVSTAR/GPS series; Solar Maximum Mission; AMPTE, SPARTAN, Space Telescope, Magellan, GRO, UARS, EUVE, TOPEX, GOES, MGS, MSP, MTSAT and TRMM. Louvers are thermally activated shutters that regulate the structural and electronic equipment thermal- environment during spaceflight. The louver assemblies sense the temperature of a baseplate, or space radiator, and react to control that temperature. These assemblies consist of highly-polished aluminum blades set in a frame and driven by bi-metallic sensors. (See Figure 1.) As the temperature increases, the bi-metallic sensor, or actuator, contracts and applies torque to rotate the blades toward an open position, thereby allowing heat to dissipate. As the temperature decreases, the actuator expands, Features • Lightweight • Self-contained • Available in many proven geometric configurations • Maintains temperature control over wide spectrums • Uses no power • Configurable for mission-unique requirements • Fully-qualified for various satellite requirements • Sun shielded configuration available • Laser impingement protection available • Cover for Micrometeorite or EVA protection flight proven and available. Thermal Control Louvers Sizes Orbital has provided thermal control louvers for many spacecraft in numerous sizes. The following table represents fabricated louver sizes readily available for delivery; however, tailored geometric configuration can be supplied to specification. Description Orbital Technical Services Division 5010 Herzel Place Beltsville, MD 20705 Phone: (301) 902-1152 Fax: (301) 931-0396 www.orbital.com Program Number Length Width Weight ➂ Area Weight/Area M/N Name of Blades cm (in) cm (in) kg (lbs) m 2 (ft 2 ) kg/m 2 (lbs/ft 2 ) 41901 AMPTE ➀ 3 20.00 (07.88) 36.20 (14.25) 0.37 (0.81) .072 (0.78) 5.14 (1.04) 61201 GOES ➀ 20 63.35 (24.94) 60.96 (24.00) 1.62 (3.57) .386 (4.16) 4.20 (0.86) Space Telescope ➀ 24 75.72 (29.81) 60.96 (24.00) 1.95 (4.30) .462 (4.97) 4.22 (0.86) JRI/XTE ➀ 22 69.55 (27.38) 50.80 (19.99) 1.63 (3.60) .353 (3.80) 4.61 (0.95) GPS 16 42.01 (16.54) 59.70 (23.50) 0.82 (1.81) .250 (2.70) 3.28 (0.67) 31801 VRM Magellan ➁ 16 42.01 (16.54) 39.37 (15.50) 0.63 (1.40) .165 (1.78) 3.82 (0.78) 45001 GPS/Spartan 18 47.10 (18.54) 54.86 (21.60) 0.91 (2.00) .250 (2.77) 3.64 (0.72) 45002 SPARTAN 26 67.41 (26.54) 54.86 (21.60) 1.16 (2.56) .368 (3.96) 3.15 (0.65) GRO/Topex ➁ 26 72.44 (28.52) 55.63 (21.90) 1.77 (3.90) .403 (4.34) 4.39 (0.90) MMS/UARS, Topex ➁ 42 110.33 (43.44) 55.63 (21.90) 2.63 (5.78) .614 (6.61) 4.28 (0.87) 5K202 MGS ➁ 10 26.77 (10.54) 40.50 (15.95) 0.58 (1.27) .108 (1.17) 5.37 (1.08) 5K201 MGS ➁ 16 42.01 (16.54) 40.50 (15.95) 0.84 (1.83) .170 (1.83) 4.91 (1.00) 5L1021 MSP 14 36.93 (14.54) 40.50 (15.95) 0.68 (1.49) .148 (1.61) 4.59 (0.93) ➀ Louver blade operation open to closed = 10°C (18°F); all other open to close = 18°C (30°F) ➁ Design includes sunshield ➂ Weight w/o sun shield or mounting hardware
