Downloaded from https://www.everyspec.com MIL-STD-81OC 2.2.2.1 Cpen structure line source. Quartz lamps, carbon cloth, tungsten wire, strip and tubular heaters, end other similar means may be utillzed to simulate the heating effects of solar energy, planet radiation, and albedo on test specimens within cryogenicallycooled space simulation chamhers. Radiation units and supporting structures shall be designed for minimum blockage area, ease of mounting, low out-gassing, and controllability of radiation intensity. 2.3 Heat sink (radiant). Both the temperature and emissivity,or blackness, of the cryogenic shrouds are importantparameters in simulating the blackness, of space.
The low temperature reduces the radiation emitted by the walls in accordance with the Stefan-BoltzmannLaw, and the high emissivity causes the walIs to absorb any radiation impinging upon them rather than reflecting the energy back to the test vehicle. A 100° Kelvin wall with a 0.95 emissivity will simulate the space environmentto within 1 percent for a 300° Kelvin vehicle. Radiation can leave the surface of the chamber by either reflection or emission and control of both is necessary to maintain good simulation of the space envi~onment. Total reflected end emitted radiation, exclusive of the solar simulation arriving at the test vehicle shallbe less than 50 watts per square meter.
2.3.1 Warm surfaces, such as windows, feed-throughports, chamber wal1s, etc, should be kept to a minimum and should be covered with cooled pIates when they are not in use. ) 2.4 Contamination controls. Contamination levels shall be controlled and measured to insure that emissivity and absorptive values are not altered by more than 5 percent of the initial values of the flight or test hardware from time of acceptance of test article to completion of the test. 3. PREPARATION FOR TEST 3.1 Informationrequired. In preparing the specimen for a teat, typical information required is: I a. Need fOr simulating planet/moon radiation and albedo. b.
Rotational modes and attitude orientation, as applicable. c. Programming solar radiation in accordancewith the mission (considering the day and night orbiting periods plus cislunar and translunar missions) . d. Equipment operation duty cycles. 517,2-5 METHOD 517.2