The Dawn spacecraft is launched by NASA in September 2007 in order to travel to the two oldest and largest asteroids in our solar system, '4 Vesta' and '1 Ceres'. Powered by ion electrical propulsion it will arrive at Vesta in 2011. After conducting experiments and measurements for seven months it will travel again for three years in order to arrive at Ceres. There it will perform similar tasks. The state-of-the-art propulsion system requires powerful solar arrays to provide the necessary electrical energy.
Dawn solar array
Prime contractor Orbital Science Corporation (OSC; Dulles, USA) awarded the contract for the design, production, assembly and testing of the solar array to Dutch Space. The solar array is a full member of the ARA family. It consists of two wings of five solar panels each measuring 1.6x2.2 m2. They are covered by almost 13 000 state-of-the-art gallium arsenide solar cells and they are capable of providing more than 10 900 Watt at BOL (Begin Of Life) conditions immediately after deployment near earth. Once the satellite has come to the end of its mission however, the distance to the sun has increased dramatically. The combined effect of both degradation through radiation and the reduced solar intensity and temperature results then in a maximum power of only 1 400 Watts.