Dawn’s journey ever-deeper into the asteroid belt continues to go well, as the spacecraft carries out its familiar routine of thrusting gently with its ion propulsion system. But the interplanetary traveler has changed some of its habits, performing certain activities a little differently now from what its many followers have been accustomed to.

Dawn is now so far from the sun, that even with its tremendous solar arrays, the most powerful ever used on an interplanetary mission, it does not receive enough sunlight to generate sufficient electrical power to operate all systems and still achieve maximum thrust.

The largest consumer of power onboard the ship, the ion propulsion system is power hungry. Indeed, the key to its remarkable effectiveness is that, in concert with the solar arrays, it converts the renewable energy from the omnipresent sunlight into thrust with a high velocity beam of xenon ions, in contrast to conventional propulsion systems, which only work with the more limited energy stored within the chemical propellants. … (SpaceDaily)