Moog Throttle Valves Lessens “Seven Minutes of Terror” for Curiosity

8 August 2012

Moog and its propulsion engineers celebrated with NASA and the rest of the space community after the successful landing of the Mars Science Laboratory’s (MSL) Curiosity rover on August 5, 2012.  Moog technology had an important part in ensuring that the “seven minutes of terror “ ended in a smooth landing for Curiosity.  Moog supplied a total of twenty-six propulsion valves for the mission, ten on the cruise stage and sixteen on the descent phase.

Like previous Mars rover missions, Moog provided solenoid thruster valves to help steer the mission in its cruise phase to Mars.  Moog also provided fill and drain valves for the hydrazine propulsion systems.  These valves were used to help load the hydrazine propellant safely onto the spacecraft prior to launch.  

For the final descent phase of the mission, Moog produced unique Cavitating venturi valves for the 800 lbf engines that were used to control the descent module.  These valves were developed to provide throttleable thrust for the engines so that Curiosity could be safely lowered onto the surface of Mars.

Moog developed the cavitating venturi valves in conjunction with JPL and Aerojet to support the descent phase of the MSL.  The advantage of the Moog throttle valve assembly (TVA) over other traditional propellant valves is its ability to continuously and accurately throttle propellant  flow from 1% to 100% through a varied duty cycle while maintaining stable flow despite rapid fluctuations in engine backpressure.  Within the TVA, the valve position is precision controlled by a Moog Inc. designed electromechanical actuator (EMA) that is tethered to the control pintle of the valve. The TVA used in the MSL descent engine regulates flow from 0.033 to 3.3 lb/sec (hydrazine) and can achieve full stroke within 70 milliseconds after application of command.  

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