During its time in orbit around Vesta, the probe experienced several failures of its reaction wheels. Investigators planned to modify their activities upon arrival at Ceres for close range geographical survey mapping. The "Dawn" team stated that they would orient the probe using a "hybrid" mode utilizing both reaction wheels and ion thrusters. Engineers determined that this hybrid mode would conserve fuel. On November 13, 2013, during the transit, in a test preparation, "Dawn" engineers completed a 27-hour-long series of exercises of said hybrid mode.