Performance of high-efficiency advanced triple-junction solar panels for the LILT Mission Dawn

NASA´s Discovery Mission Dawn is designed to operate within the solar system´s Asteroid belt, where the large distance from the sun creates a low-intensity, low-temperature (LILT) condition. To meet the mission power requirements under LILT conditions, very high-efficiency multijunction solar cells were selected to power the spacecraft to be built by Orbital Sciences Corporation (OSC) under contract to JPL. Emcore´s InGaP/InGaAs/Ge advanced triple-junction (ATJ) solar cells, exhibiting an average air mass zero (AM0) efficiency of greater than 27.6% (one-sun, 28°C), were used to populate the solar panels. The two solar array wings, to be built by Dutch Space, with 5 large-area panels each (total area of 36.4 m²) are projected to produce between 10.3 kWe and 1.3 kWe of end-of-life (EOL) power in the 1.0 to 3.0 AU range, respectively. The details of the solar panel design, testing and power analysis are presented.