Gemini Spacecraft

Organization Description

Gemini Pedistle 

Navigation vents

Direct Command Mode 

Direct Mode

In this mode, thruster firing commands are applied directly to the RCS or OAME attitude solenoid valve drivers by actuation of the attitude hand controller direct switches. Selection of the direct mode applies a bias voltage to a transistor designated ground switch A. Conduction of the transistor completes a circuit to ground which is common to one side of the hand controller direct switches. The transistor remains on as long as the direct mode is selected. Six normally-open switch contacts provide the command signals in the pitch, yaw and roll axes and will close when the hand controller is moved beyond a preset threshold (2.5 degrees) of handle travel. Deflection in the desired direction applies a ground from switch A directly to the valve driver relative to that direction which, in turn, fires the proper thruster(s). Thrusters continue firing as long as the hand controller is displaced beyond the 2.5 degree threshold. This mode of operation is optional at all times.