Downloaded from https://www.everyspec.com MIL-STD-81OC Temporal variation of intensity in the test volume shall not deviate from the average as listed in table 517.2-111 for that class,uniformity. Intensity and uniformity measurements shall be made with a sensor of area2equal to O.1 of I percent of the rated area but in no case smalIer than 1 cm or larger than 10 cm2. It is likely that the spectrum of the simulated radiation will differ in certain wavelength regions from the spectrum of the”assumed true solar radiation, listed in table 517.2-IV.
Total effective absorptance of the surface of the test item should not differ significantly from the total solar absorptance value if test item temperature errors are.to be avoided. Table 517.2-IV. Solar ElectromagneticEnergy Distribution Percent of total Wavelength band Allowable variation Band No. solar irradiance (angstroms) of band energy, percent 1, 2.7 2,500-3,300 f50 2 19.7 3,300-5,000 *25 3 24.3 S,000-7,000 *1O 4. 16.5 7,000-9,000 *1O .5 11.0 9,000-11,000 *15 6 12.2 11,000-1s,000 *2O 7 9.7 15,000-25,000 t30 ( ,. 2.2.2 Heat flux simulator.
The thermal effects of the space environment uPOn a spacecraft maY ‘besimulated using radiant energy sources entirely in the infrared (heat) portion of the spectrum under either of the following conditions: a. If a piece of equipment is shielded from direct view of Sun and planets in f1ight mode b. If a spacecraft or a piece of equipment which is directly viewed by the Sun and planets is configured such that a thernialsource will supply the same heating effect as a source simulating the spectrum and collimation of the sun would. This would be applicable for an equipment:
(I) with a uniform external finish u/E (Alpha/Epsilon), (2) with no sensitive parts mounted in deep crevices, where the collimationof the radiation would be important, or (3) where the rotational motion in space would be such as to result in effectivelyuniform I solar planet illumination sufficient to cancel nonuniform ci/ssurface finishes. the effects of crevi~es and I 517;2-4 METHOD 517.2