Lunar orbit rendezvous

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Diagram of a LOR

The lunar orbit rendezvous ( LOR ) is a key concept for efficiently landing spaceships on the moon and returning them to earth . It was used for the missions of the Apollo program in the 1960s and 1970s and is also included in the concept of the successor program Artemis . In a LOR mission, a main spaceship as an orbiter and a smaller lunar module travel into lunar orbit . The lunar module then sinks automatically to the surface of the moon, while the main ship remains in orbit. Upon completion of the surface mission, the lander will return to lunar orbit to meet and re-dock with the main spacecraft. After the transfer of crew and payload, he was abandoned in the Apollo program; only the main spaceship returned to earth.

In 1919, the Ukrainian-Soviet engineer Yuri Kondratyuk was the first to propose a rendezvous in lunar orbit to send a person on a return trip to the moon.

The most famous examples were the Apollo command and service module and the Apollo lunar landing module, both of which were sent on a translunar flight in a single rocket. There are also concepts in which the lander and main satellite travel separately, such as the Shuttle-Derived Heavy Lift Launch Vehicle and a variant of the Artemis program.

advantages and disadvantages

advantages

Gravitational diagram

The main benefit of a LOR is that it saves weight on the lunar lander because the fuel required to return to Earth from lunar orbit does not need to be carried to the surface of the moon and back into orbit. This has a multiplicative effect as every pound of the “dead weight” of propellant used later has to be propelled by more propellant. The resulting increase in weight would also require more thrust for the moon landing, which means bigger and heavier engines.

Another advantage is that the lunar module and the main spacecraft can each be specialized and optimized for their purpose. Finally, the second set of life support systems that the lunar lander needs can also serve as a backup for the systems in the main spacecraft.

disadvantage

Risks

Initially, the rendezvous in lunar orbit was considered risky, as no rendezvous had yet taken place even in earth orbit. If the lunar module could not reach the main spacecraft, two astronauts , related to the Apollo lunar module , would have been stranded with no way to return to Earth or survive re-entry into the atmosphere. The fear turned out to be unfounded, since the rendezvous were successfully demonstrated on six missions of the Gemini program in 1965 and 1966 with the help of radar and on-board computers. It was also performed successfully every time it was tried on Apollo missions.

Web links

Individual evidence

  1. ^ "Lunar Orbit Rendezvous" - 1968 - NASA Mission Planning and Analysis Division on YouTube