It’s been 50 years since Neil Armstrong took the first-ever human steps on the moon.

After a 380 000 kilometre journey, the crew set foot on the Moon, walked on it, installed scientific instruments, took samples, and then departed for Earth.

Three days after leaving the moon on July 24, 1969, they landed back on Earth, in the ocean.

Sounds simple when you put it like that, but the number of things that could go wrong was off the charts. One mistake that went undetected, in particular, could have guaranteed a very different ending to the moon landing story that we know today.

Over to Forbes:

But of the innumerable things that could go wrong, one of them was entirely unexpected: the possibility that the Service Module, scheduled to break apart and safely burn up in Earth’s atmosphere, could accidentally have a piece of its debris collide with the Command Module, ruining re-entry and killing the returning astronauts on board.

The plan to avoid it was simple: the Service Module, post-separation, would perform a series of thrust maneuvers to take it safely away from the re-entry path of the Command Module.

By shifting the Service Module to a significantly different trajectory, it wouldn’t even re-enter at the same time as the Command Module, but would skip off the atmosphere this time.

The re-entry of the Service Module should have only come much later, after performing another orbit (or set of orbits) around Earth.

But that’s not what happened. Pilot Frank A. Brown, who was flying about 725 km away from the re-entry point, reported the following:

I see the two of them, one above the other. One is the Command Module; the other is the Service Module…I see the trail behind them — what a spectacle! You can see the bits flying off. Notice that the top one is almost unchanged while the bottom one is shattering into pieces. That is the disintegrating Service Module.

Fortunately for everyone, none of the debris hit the Command Module, which arrived safely back on Earth.

But it was a little too close for comfort.

You can watch footage of the takeoff and moon landing here.

[source:forbes]