Staying calm under pressure is just one of the many challenges when you're undertaking an especially audacious venture. Take the example of Neil Armstrong, who landed on the moon while maintaining a heart rate of 156 beats per minute. (A normal heart rate has less than 100.)

It's been 50 years since U.S. astronauts first walked on the moon, but new details about NASA's most celebrated mission are still being brought to light. The new documentary  Apollo 11 features never-before-seen NASA footage that, amazingly, had been sitting untouched at the National Archives and Records Administration for nearly half a century. The movie premiered at the Sundance Film Festival in January and hit theaters on March 1.

Directed by Todd Douglas Miller, whose previous documentary Dinosaur 13 focused on the discovery of the largest Tyrannosaurus rex fossil ever found, Apollo 11 offers viewers a fascinating window onto one of the greatest technological achievements of the 20th century. Comprised entirely of archival footage from 1969 shot on vivid 70mm film, the documentary serves as an inspiring example of the U.S. accomplishing a Herculean task in uncharted territory. As Armstrong points out in the film, in embarking on a mission that no humans had ever attempted before, the margin of error for the Apollo 11 crew was virtually zero.

"Each segment of the mission--every individual piece--has to be completed perfectly in order for the next step to be possible," Armstrong says.

Beginning on July 16, 1969, just hours before Armstrong, Buzz Aldrin, and Michael Collins board the Saturn V rocket, the film captures every phase of the mission in stunning detail, with footage of everything from the inside of the spacecraft to the surface of the moon. Additional clips and audio recordings of NASA employees at Mission Control in Houston reveal how engineers on the ground worked to troubleshoot several problems during the mission. On the morning of the launch, for example, technicians had to fix a leak in a liquid hydrogen valve on the launchpad 200 feet above the ground.

Among the most surprising revelations from the film is the astronauts' ability to remain calm under intense pressure, thanks primarily to speedy assistance from Mission Control. While landing the Eagle lunar module on the moon, Armstrong had to maintain his composure as alarms repeatedly signaled that the Eagle's guidance computer was overloaded with data.

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Despite the seriousness of their mission, none of the astronauts lost their sense of humor in space. When capsule communicator Charles Duke noted that the sensors on Collins's body had stopped transmitting his respiration rate data, Collins responded by saying, "I promise to let you know if I stop breathing." Even as Aldrin took his historic steps down the lunar module ladder to follow Armstrong onto the moon's surface on July 24, 1969, he joked that he was about to "close the hatch, making sure not to lock it on my way out." Laughing, Armstrong replied, "A pretty good thought."

While the task of flying to the moon and back fell on the shoulders of Apollo 11's three-person crew, during their final television broadcast from space, the astronauts noted that the success of the mission depended on the efforts of thousands of people. "We'd like to give a special thanks to all those Americans who built those spacecraft, who did the construction, design, the tests, and put their hearts and all their abilities into those craft," Armstrong said.

Though Apollo 11 serves as a reminder of what can be accomplished when people work toward a common goal, it also underscores the importance of dreaming big, as President John F. Kennedy did when he set the goal of reaching the moon by the end of the 1960s. It's worth noting that the film's release coincides not only with the 50-year anniversary of the moon landing, but also with another historic milestone: the first-ever private moon mission, launched just last week by Elon Musk's SpaceX.

Ending with a clip of Kennedy's 1962 speech on the space effort, in which he called the decision to go to the moon "an act of faith and vision," Apollo 11 ultimately appeals to the human instinct to be bold. As Kennedy said in his speech, if man can "do all this, and do it right and do it first before this decade is out, then we must be bold."