'Apollo's Daring Mission': NASA's Epic Apollo 8 Moonshot Stars in PBS Documentary

This Christmas season marks the 50th anniversary of one of humankind's most memorable spaceflights: the Apollo 8 moon mission. 

The Apollo 8 astronauts circled the moon in December 1968, marking the first time human ever saw the lunar surface from up close with their own eyes. And like every good astronaut today, the Apollo 8 crew brought the public along using cutting-edge technology of the day – color television. To chronicle that epic flight, a new documentary "Apollo's Daring Mission" will air tonight (Dec. 26) on PBS at 9 p.m. EST (or 8 p.m. CST, depending on the time zone you see it in).

While many today remember Apollo 8 as a shining triumph, the new documentary reminds viewers that the Apollo moon program was fighting for its life at the time. [Apollo 8: NASA's First Crewed Trip Around the Moon in Pictures]

"I've always been a fan of the space program," said filmmaker Rushmore DeNooyer in a Space.com interview. "I was lucky to have lived through a lot of these Apollo missions, and I was old enough to follow it and be excited about it."

As DeNooyer's film shows, less than two years before Frank Borman, Jim Lovell and Bill Anders made their daring voyage to the moon, three fellow astronauts and friends died in a terrible pad fire during preparation for the Apollo 1 mission.

NASA swiftly implemented managerial and technical changes, and DeNooyer said the tragedy taught the agency a lot about spaceflight. While there were many causes for the Apollo 1 fire, the most famous ones are the pure oxygen atmosphere in the spacecraft – which accelerated the fire – and the hatch that proved too difficult for astronauts to open in an emergency. NASA addressed both design problems in future spacecraft.

"What they learned from that probably helped them get to the moon successfully," DeNooyer said. With new knowledge in hand, NASA flew Apollo 7 safely in October 1968, but doubt still persisted; could the agency meet its goal of landing humans safely on the moon by the end of 1969?

Adding drama was a space race. Today Russia's space agency is a partner of NASA and they work together daily on the International Space Station, but the 1960s was a different era altogether. Swept up by the Cold War, both the Soviet Union and the United States tried to one-up each other in space milestones to show technological prowess.

The Soviets racked up milestones such as the first person in space, the first two-person crew and the first three-person crew, while the Americans did the first docking and broke altitude records above Earth. The moon was NASA's ultimate goal, however, intelligence flowed from the closed Soviet society that the other country also wanted to plan a moonshot to upstage the United States.

Apollo 8 was a gamble. At first, NASA planned to keep Apollo 8 in low-Earth orbit to test out spacecraft and systems. But with the Soviets dogging NASA's heels, the agency surveyed its people to see if they were ready to push out to the moon. Flight controller Jerry Bostick was one of that small group who knew before news became public.

"I was a part of a handful of guys who started working on it in secret; we couldn't tell anybody what we were doing," Bostick said in a separate interview with Space.com. While the decision to go was obviously elating for the public, Bostick said all was "serious business" in Mission Control, where employees knew they were undertaking a dangerous mission. "The flight to the moon was coming earlier than what we had expected," he said, and they wanted to be ready.

Spoiler alert: Apollo 8 was a spectacular success, and one of the key milestones along the long road to landing Apollo 11 on the moon on July 20, 1969. The mission also generated a photo that Bostick jokes must be on 75% of people's desktops, including his – Earth's glowing globe silently sitting above the moon's surface, an Anders photo that space people call "the Earthrise picture."

"I'm told that Bill Anders has the picture in his home, and it's rotated 90 degrees because that's the way they really saw it – with the earth off to the left, and the lunar surface vertically to the right," Bostick said.

While Apollo 8's story is well-documented, DeNooyer says there are parts of history that are more ignored – such as the role of the guidance computer, or the help of mission controllers who kept Apollo 8 safe during a week of spaceflight far from home. This former teenaged fan of Apollo said it was the chance of a lifetime to speak with former mission controllers Bostick and John Aaron to learn more about Apollo 8's story.

"It's a privilege, I think, to sit down and talk to them, and they put a tremendous amount into getting us to the moon," DeNooyer said. "I mean, this wasn't Monday through Friday, 9 til 5."

"Apollo's Daring Mission " premieres tonight, Dec. 26, on PBS at 9 p.m. EST/PST (8 p.m. CST). Check local listings.

Follow us on Twitter @Spacedotcom and on Facebook. Original article on Space.com.