Lunar Orbit Insertion

Lunar orbit insertion (LOI) is an orbital maneuver by means of which a spacecraft is placed on a selenocentric orbit. This was one of two concepts that were being considered by the NASA engineers, during the planning of the Apollo Moon mission. Werner von Braun and his German colleagues were set against this idea, preferring a direct landing of a large rocket, on the Moon. Von Braun argued that the maneuver, including the difficult challenge of the Lunar Excursion Module having to rendezvous with the Command Module, would be too difficult and dangerous for mere astronauts to be able to accomplish. Von Braun's concept, although simpler, was deemed too expensive and cumbersome, due to the need for the rocket to be large enough to carry enough fuel, so that it could lift off the lunar surface, in order to return to Earth. The LOI concept was more complex but, it was also much more efficient and elegant, from an engineering point of view. The LOI concept was the one that was finally adopted, after much heated debate.