Apollo 11 launched on July 16, and the rest is history, with Armstrong and Buzz Aldrin touching down four days later before a two-hour moonwalk watched by hundreds of millions of people. However, NASA’s website reveals a lesser-known story – that of Luna 15, the second Soviet attempt to recover and bring lunar soil back to Earth, which was originally scheduled to touch down while the pair were on the lunar surface. Launched in Kazakhstan just before 3am GMT on July 13 – three days before Armstrong, Aldrin and Michael Collins took off in a Saturn 5 rocket from Kennedy Space Center in Florida – Luna 15 was an unmanned mission, with the probe weighing 12,500lb.
However, before being launched, because of mass constraints, its designers were forced to remove two three-pound radio transmitters, leaving just one for the entire journey
On the way to the Moon, abnormally high temperatures in Luna 15’s propellant tanks, which fed its S5.61 engine, meaning they had to manouvre the craft to keep it in the Sun’s shadow to minimuse the risk of a catastrophic explosion.
Controllers made a course correction the day after launch, and Luna 15 entered lunar orbit at 10am GMT on July 17, 1969, while Apollo 11 was still on its way.
Two orbital corrections were eventually carried out on July 19 and 20 to put Luna 15 into its planned orbit in preparation for an attempted landing.
NASA’s website says: “The original plan was for Luna 15 to embark on the Moon less than 2 hours after Apollo 11, but it was not to be.
“Unsure of the terrain below, controllers delayed the landing by another 18 hours.”
By the time the landing attempt was made, Armstrong and Aldrin were back in the lunar module preparing to take off for their return journey.
Eventially, at 3.46 and 43 seconds GMT on July 21, 1969, barely two hours before the Apollo 11 took off, Luna 15, now on its 52nd orbit around the Moon, began its descent.
The plan was to fire the main rocket for 267.3 seconds and bring the vehicle down to about 1.6 miles (2.5 kilometres) altitude.
However, during the descent, transmissions from the vehicle abruptly stopped after 237 seconds, at which pointed indicated the spacecraft was about two miles above the lunar surface.
NASA adds: “Later analysis indicated that Luna 15 had probably crashed onto the side of a mountain (at something like 298 miles per hour or 480 kilometers per hour) as a result of incorrect attitude of the vehicle at the time of ignition of the descent engine – in other words, the spacecraft was probably descending not directly towards the surface, but at a slight angle.
“Luna 15 crashed about nine miles (15 kilometers) laterally away and 28 miles (45 kilometers) ahead of its assumed location.
“Impact was roughly at 17 degrees north latitude and 60 degrees east longitude in Mare Crisium.”
Audio recordings of British technicians at the Jodrell Bank observing Luna 15’s descent were made available to the public on July 3, 2009.
Significantly, despite the fiercely competitive space race, the USSR did actually share the Luna 15 flight plan with NASA to minimise the chances of a collision with Apollo 11 – although the precise nature of the mission was not revealed.
