4 .0 Calculation of Radiance from the Sun Reflected by the Elements of SPS. Clearly, from equation (7), if any elements of the SPS reflected the entire solar disc (^0.5 degree in diameter) to populated areas of the earth, from near the zenith, it would present a serious hazard, if people were somehow induced to look at it out of curiosity. We would expect, of course, that they would find it too painful to look at for more than a brief glance, but the 0.84 permissible seconds is very brief; also, there have been cases of eclipse blindness, so we cannot count on glare as a deterrent. Fortunately, according to the analysis of the SPS made by the Boeing Corp. (14) no element of the SPS reflects the entire solar disc, even including the error modes that they consider, where the front surface of the satellite reflects the sun to the earth because the satellite is out of control. We have chosen from the Boeing report the elements and conditions which produce the highest irradiances on earth, using our own calculations of the blue light hazard function integral with sunlight to estimate the maximum safe viewing time. The worst case according to Boeing is misalignment of the OTV in LEO to produce specular reflections from the glass fronts of the solar panels. In analyzing this case, we must decide whether the extended source formula (2) or the point source formula (8) should be used. The OTV in LEO is 1.51 km across. At 910 km distance from the earth it subtends: = 0.17 or 17 percent of the solar disc in diameter, roughly 1 .9 X 10-D steradian in solid angle. Thus, this case falls within the point -4 source definition of smaller than 1 X 10 sr., so we use the point source calculation of equation (8). It should be noted that if this were an instantaneous exposure with a point source, the irradiance would be independent of the size of the source. It would be presumed to have the same effect as
RkJQdWJsaXNoZXIy MTU5NjU0Mg==