Apollo 10: the full‑scale rehearsal

Apollo 10 was a full‑scale rehearsal of the moon landing expedition, flown by Tom Stafford, Gene Cernan and John Young. They made two orbits of the moon and flew the LEM less than 50,000 feet above the surface.

In January 1969, the Soviets still needed to test their re‑entry module before they were ready for a circumlunar fly‑by. On 14 January Soyuz 4 and Soyuz 5 made a rendezvous which included an EVA transfer.

On 4 July the Soviets were preparing a fully manned flight test of their lunar landing system involving both their new G‑1 booster and a Proton booster. The G‑1 would carry a 50‑ton unmanned composite lunar spacecraft into orbit, while the Proton would launch a Soyuz carrying three cosmonauts. Their mission would be to rendezvous and dock with the lunar payload. While the G‑1 booster was being fuelled an American satellite was observing it when an electrical short ignited fuel in the third stage and almost 3,000 tons of propellant exploded. Naturally the mission was cancelled.

Aldrin would take an Apollo I mission patch and Soviet medals honouring the deceased cosmonauts, Gagarin and Komarov, to leave behind on the moon:

The commander of the LEM was next to the hatch so it was practical that he should be the first to walk on the moon.