3.1.2.1 Description of Spacecraft Elements The major structures of the SPS system are the staging base (SB), the electrical orbital transfer vehicle (OTV) and the solar power satellite (SPS). In this section a general vector approach will be presented which allows one to determine what reflections from structural elements will strike the earth. The major reflection surfaces will be identified for each of the three vehicles. The following explicit parameters will be needed in the specular reflection calculations: 1. Orientation of structural elements, 2. The total area of all elements of a given type, 3. The specular reflectance, p 4. The spreading angle, t, due to uneven surfaces. Each major system, the SB, the OTV, and the SPS will be treated separately below. The above parameters along with the direction cosines of the reflected light will be tabulated for the major elements of each major system. The reflection unit vector r shown in Figure 3 can be expressed in terms of the incident and normal unit vectors i, n. Appendix A gives the computer program for vector rotation which was used to find the direction cosines of the surface normals for each of the major systems which are presented in Tables 1-3. STAGING BASE The SB alone is shown in Figure 4, and construction of an OTV on the SB is shown in Figure 5. The coordinate systems for the vector calculations are defined in Figure 6. The plane defined by vectors a and c is the ecliptic plane while the i - k plane is the orbital plane with an inclination (Kennedy launch) of about 30°. The SB and the OTV lie in this plane so that x = i, y = j, and z = k. Table 1 gives parameters for the various SB elements defined in the figures. All elements are assumed to be covered with Z-93 white paint with a specular reflectance of 0.75. Note the battens (which are triangular structural members which, along with cables, hold three stringers in a rigid beam) provide considerably less area than the beams and attached equipment.
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