5.2 to 11.6

Right History

Nimbus, Landsat,OAO, ATS-6, Viking, GPS, SolarMax, AM PTE, SPARTAN, Hubble, Magellan, GRO, UARS, EUVE, TOPEX, GOES, MGS, MSP

XTE, Stardust

Rosetta, Quickblrd, J PL0: Mariner, Viking, Voyager, Galileo, MLS, Magellan, TOPEX, NSCAT, Cassini. Seawinds

aThls table contains representative values from past louver designs. Contact manufacturer for additional design possibilities or values for specific designs. "Weight without sunshleld.

c The Starsys design Is a slightly modified version of a JPL louver design that has flown on the Indicated spacecraft.

The effective emittance for some representative louvered-radiator designs are shown in Table 11-47B. Note that the emittance range for the MMS Landsat-4 design that uses a sunshield is considerably less than the other designs that do not have sunshields. The apparent emissivity advantage of the unshielded designs, however, is at least partly counteracted by the fact that the unshielded louvers will trap sunlight between the open blades, which adds an additional heat load that must be rejected. The choice of a shielded or unshielded design for any particular radiator will depend on the results of the analyses that show the relative performance of each option given the solar illumination profile for that particular radiator.

TABLE 11-47B. Louvers Effective Emissivity Variations with Temperature (test data).

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