 The first row consisted of several controllers, the Booster Systems Engineer (BOOSTER), Flight Surgeon (SURGEON), capsule communicator (CAPCOM), Retrofire Officer (RETRO), Flight Dynamics Officer (FIDO), and Guidance Officer (GUIDO).The BOOSTER controller, depending upon the type of rocket being used, was either an engineer from the Marshall Space Flight Center (for Mercury-Redstone flights) or an Air Force engineer (for Mercury-Atlas and later Gemini-Titan flights) assigned for that mission.The BOOSTER controller's job would last no more than six hours total and he would vacate his console after the booster was jettisoned.