irradiance are to paint specular surfaces with diffuse paints, and to avoid unfavorable geometries with corrective thrusting. The East-West width, sru, of the illuminated noontime spot on the earth tW Q (latitude 21°S) can be found from the sun's diameter (1.4 x 10 m), its distance from earth (1.5 x 10^ m) and the distance R = 910 km: The North-South length, sN<;, is found using the angle, 62°, between the 11 o reflected ray and the normal to the earth’s surface: Neglecting the rotation speed of the earth, the speed of the spot is the same as the OTV/SB speed in LEO which is 8.2 km/sec. Thus, the spot requires about one second to pass the noontime longitude. CASE S2: SATELLITE SOLAR PANEL IN GEO, EQUINOX CASE This case is depicted in Figure 27. (The view is normal to the ecliptic plane.) Grazing sunlight is refracted about 1° as it passes the earth's limb. For the satellite in the indicated position in GEO and at an equinox, the light will be reflected back to the earth's night side by the solar panel facing the sun. The following representative parameters are used in Eq. (1): 2 Here, an irradiance of 0.03 W/m is found for optically flat mirror conditions.
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