THE LUNAR MODULE FLIES: APOLLO 5

Launched on 22 January 1968, Apollo 5 is the flight that history treats almost as a footnote. It was neither manned nor did it have the remarkable Saturn V as its launch vehicle. It used the AS-204 launch vehicle that had been intended to lift Apollo 1, but it is important to the story because, as a В-mission, it tested the first Apollo lunar module, LM-1. The test allowed engineers to verify the lunar module’s structure and its response to the launch environment, and it gave them their first

opportunity to test the spacecraft’s two engines in the space environment.

In the case of the ascent engine, it was NASA’s first opportunity to try out a fire-in-the-hole burn when they ignited the ascent engine just as the descent stage was being jettisoned. In their effort to give crews the best possible chance of escape from any reasonable failure of equipment, the LM’s designers planned that if the descent engine should fail while a crew were descending to the Moon, the ascent engine should fire and lift the crew back to the safety of an orbit. For this to happen, its engine would have to ignite while the descent stage was still in place. Despite some problems, the legless module successfully demon­strated everything that was asked of it,
and a second В-mission was cancelled. The second test lander. LM-2, is now on display at the National Air and Space Museum in Washington DC. 1’he next spacecraft to fly, LM-3, would be entrusted with the lives of two men.