The "Dawn" spacecraft was propelled by three xenon ion thrusters derived from NSTAR technology used by the "Deep Space 1" spacecraft, using one at a time. They have a specific impulse of 3,100 s and produce a thrust of 90 mN. The whole spacecraft, including the ion propulsion thrusters, was powered by a 10 kW (at 1 AU) triple-junction gallium arsenide photovoltaic solar array manufactured by Dutch Space. "Dawn" was allocated of xenon for its Vesta approach, and carried another to reach Ceres, out of a total capacity of of on-board propellant. With the propellant it carried, "Dawn" was able to perform a velocity change of approximately 11 km/s over the course of its mission, far more than any previous spacecraft achieved with onboard propellant after separation from its launch rocket. However, the thrust was very gentle; it took four days at full throttle to accelerate "Dawn" from zero to 60 mph (96 km/h).