1. The solar array of a three-axis stabilized geostationary satellite has the following properties:
area: \( 6 \mathrm{~m}^{2} \)
absorptivity, front and back face of solar array: 0.8
emissivity, front face of solar array: 0.8
emissivity, back face of solar array: 0.7
ratio, active cell area to front face area: 0.95
solar cell efficiency: \( 14 \% \)
solar constant, vernal equinox: \( 1362 \mathrm{~W} / \mathrm{m}^{2} \)
solar constant, summer solstice: \( 1321 \mathrm{~W} / \mathrm{m}^{2} \)
Stephan—Boltzmann constant: \( 5.67 \times 10^{-8} \mathrm{~W} / \mathrm{m}^{2} \mathrm{~K}^{4} \)
Ignore the Earth's albedo and IR radiation. Ignore heat exchange by radiation between the array and the central body of the spacecraft.
(a) Determine the electrical power fed from the array to the main body of the spacecraft (Ans.1086.9 W).
(b) Determine the average temperature of the solar array at vernal equinox (account for the electrical power transfer) (Ans. \( 48.5 \mathrm{C} \) ).
(c) Determine the electrical power and temperature at summer solstice, where the sun's angle to the equatorial plane is 23.5 degrees (Ans. \( 966.72 \mathrm{~W}, 39.2 \mathrm{C} \) ).
