Lunex Project

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The Lunex Project was a US Air Force plan for a manned lunar landing prior to the Apollo Program. One of the biggest differences between Lunex and Apollo was the decision to land the entire spacecraft on the Moon rather than have a separate lander take some of the astronauts to the surface and rendevous with the remaining astronauts in lunar orbit for the return to Earth.

[edit] Background

Lunex planned to make its first lunar landing and return in 1967, in order to beat the Soviets and demonstrate conclusively that America could win future international competition in technology with the USSR. The Air Force felt that no achievement short of a lunar landing would have the required historical significance.

The use of the direct ascent profile was considered to be the most promising because it eliminated some of the complexities of the Lunar orbit rendezvous that would be used by Apollo: in particular there would be no need to develop rendezvous techniques in space. The down side was that the Lunex spacecraft would be much heavier than Apollo to carry the extra fuel required to land the entire spacecraft on the Moon and return it to lunar orbit, and consequently a larger rocket would be required to send it to the Moon.

The main problems to be solved were:

• Re-entry at 37,000 feet per second, with the flight path within a two-degree angle in order to avoid overheating or skipping out of the Earth's atmosphere. The latter wouldn't kill the crew directly, but would leave the Earth-return spacecraft in an elliptical orbit where they might be exposed to excessive radiation in the Van Allen belts before the next re-entry opportunity.

• Development of the lunar landing stage, which would have to make a precision landing tail-first on rocket thrust: something never previously tested.

• Development of the lunar launching stage, which had no backup capability, so must be extremely reliable and capable of automated checkout on the lunar surface, and capable of putting the crew into the correct orbit to return to Earth.

[edit] Sources

• Space Systems Division, Air Force Systems Command, Lunar Expedition Plan, May 1961
• Lunex at Astronautix.com
• Projekt "Lunex" (in German)