Near Earth Asteroid Rendezvous Spacecraft Power System Flight Performance

The Near Earth Asteroid Rendezvous spacecraft is the first to launch of the NASA Discovery programs. Its power subsystem is a direct energy transfer architecture with a Super™ nickel cadmium battery and four fixed solar panels populated with gallium arsenide on germanium solar cells. The distance from the Sun varies significantly during the mission including a record-setting 2.2-AU aphelion distance resulting in large variations in solar array I-V characteristics. To minimize the solar array size, the solar array and power system electronics are designed to operate at voltages on both sides of the array's maximum power point voltage. The power subsystem has performed as designed and has demonstrated robust performance in-flight though launch, mission aphelion, boost charging, and an attitude anomaly.