How Could a Mistake Have Killed the Apollo 11 Crew?

Fifty years later, the outstanding achievements of the Apollo 11 mission still stand as the pinnacle of manned spaceflight. For the first time in history, humans have successfully landed on the surface of another celestial body, the Moon.

The Apollo 11 crew walked 380,000 kilometers to the lunar surface, set up scientific instruments, collected samples, and finally returned to Earth after a successful mission.

But three days after leaving the Moon, on July 24, 1969, during Apollo 11’s return to Earth, A serious anomaly has occurred that put the lives of astronauts Neil Armstrong, Buzz Aldrin and Michael Collins in danger..

Behind this seemingly simple and routine task were hundreds of possible points of failure that the team had to protect itself from. A very important step was the successful re-entry of the Command and Service Module.

The Service Module is designed to crash into the Earth’s atmosphere and burn up to allow the astronauts to return safely. But, The unexpected possibility arose that the wreckage would collide with the Command Module, blocking reentry and endangering the crew..

To avoid such a disaster, the Service Module must perform post-departure thrust maneuvers to move it away from the Command Module’s re-entry path. This puts it in a different orbit, ensuring no collisions and safe re-entry. But, Due to incorrect configuration of the Service Module’s residual fuel dumpthrusters were fired in a way that endangered the mission.

The problem lay in the two types of thrusters in the Service Module: Minus X RCS jets and Roll RCS jets. The Roll jets fired in bursts to stabilize the module, while the Minus X jets fired continuously. This sustained ignition caused the Service Module to deviate from its intended trajectory and increased the risk of collision with the Command Module.

Luckily the astronauts were lucky and None of the debris from the Service Module reached the Command Module.. After the mission, a whitepaper highlighted the problem and corrective actions were implemented before the next flight, Apollo 12.

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