Earthlings first touched another world 50 years ago today. Apollo 11 astronauts Neil Armstrong and Buzz Aldrin guided their lunar module, Eagle, to a landing on the Sea of Tranquility, a volcanic plain on the Moon. It was the culmination of an eight-year effort launched by President John F. Kennedy.

The final moments of their descent to the Moon were anything but easy, though.

For a while, the astronauts had a hard time communicating with Mission Control. Their computer was overloaded, so it gave them error messages. And their radar was guiding them into a field of boulders. Armstrong had to fly past that area, burning extra fuel.

But the astronauts and flight controllers overcame the problems. And on July 20th, 1969, Eagle landed on the Moon:

EAGLE: Contact light. Okay, engine stop. ACA out of descent. Mode control both auto, descent engine command override off, engine arm off, 413 is in. CAPCOM: We copy you down, Eagle. ARMSTRONG: Houston, Tranquility Base here. The Eagle has landed. CAPCOM: Roger, Tranquility, we copy you on the ground. You’ve got a bunch of guys about to turn blue here. We’re breathing again. Thanks a lot.

We’ll talk about the next step tomorrow.

Script by Damond Benningfield