Rocket Shutdown Sequence (MSCS) - Detailed Description and Analysis - Lexicon of Rockets and Propulsion

Rocket Shutdown Sequence (MSCS) - Detailed Description and Analysis - Lexicon of Rockets and Propulsion

The Main Engine Cut Off (MECO) is a critical event during a rocket launch, marking the end of the powered phase and the beginning of the coast phase. This process is designed primarily to conserve fuel and optimize trajectory, not to separate stages or shut down secondary engines.

During a rocket launch, the onboard computer system continually monitors various parameters such as altitude, velocity, and fuel consumption. When the rocket reaches a certain altitude or velocity, as monitored by the onboard computer system, it initiates MECO. The engine control system then executes the command to shut down the main engines, stopping the flow of propellant to the engines.

For instance, during a SpaceX Falcon 9 launch, MECO happens approximately 2 minutes and 13 seconds after liftoff, following peak mechanical stress (Max Q) earlier in the flight. This is immediately followed by stage separation, which occurs a few seconds after MECO to allow safe transition to the second stage.

Before MECO, the engine controller continually manages engine throttling and propellant flow, ensuring optimal thrust and structural loads. When prespecified conditions are met—such as depletion of first-stage fuel or reaching planned velocity—the command to cut engines is sent.

After MECO, the rocket coasts through the remainder of its trajectory, using its momentum and gravity. A premature or delayed MECO can result in the rocket failing to reach its intended orbit or destination.

In summary, initiating MECO consists primarily of the flight computer and engine controllers recognising mission parameters and sending the command to shut down the main engines to end first-stage burn, preparing for stage separation. This general MECO procedure is common across many rockets, though specifics such as timing and exact control logic vary by vehicle design and mission profile.

1. The onboard computer system of a rocket, during a launch, manages various parameters including science and technology aspects like altitude, velocity, and fuel consumption, which it uses to determine when to initiate the Main Engine Cut Off (MECO).
2. After the MECO, the rocket continues its trajectory through space and astronomy, relying on its momentum and gravity, ideally reaching its destination without a premature or delayed MECO, which could disrupt its planned orbit.

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