The year is 1968, at the height of the Cold War. NASA is about to embark on its riskiest mission ever: a race to beat the Soviets in space by sending three men in a tiny capsule around the moon before the year’s end. The idea was bold and just about impossible to accomplish in such a short time frame, but America’s space program was at stake, so the flight was a go.

To mark the 50th anniversary of this historic event, Nova shares the stories of how this dangerous mission using untested technology evolved from the Apollo 8 astronauts who were part of it. Hear Commander Frank Borman, Command Module Pilot James Lovell and Lunar Module Pilot William Anders describe their amazing voyage with a scientific spin.

Travel back to 1962, when President Kennedy pledged to send Americans to the moon before the end of the decade. Struggling to keep up with the Soviet Union, NASA launched its ambitious Apollo program. But when a routine run-through of Apollo 1 in January 1967 ended in the death of three crew members, NASA immediately grounded all manned flights for 18 months while engineers scrambled to redesign the capsule.

The next five unmanned tests of Apollo were hampered by more technical problems, dealing another severe blow to the Americans’ goal of reaching the moon. Finally, in October 1968, an Apollo 7 test flight was successful, launching three astronauts into space and giving NASA the confidence to send Apollo 8 into orbit just two months later.

But just a month before Apollo 8’s scheduled launch, the CIA sent word that a Soviet rocket able to carry two men was moving into launch position. The race to the moon was on. On Dec. 21, 1968, NASA embarked on an incredible voyage, sending Borman, Lovell and Anders 230,000 miles into unchartered territory on the world’s first manned trip around the moon. Traveling at a speed of 25,000 mph, Apollo 8 soared into history.

Hear the gutsy inside story from those who were there about the remarkable feats of engineering that paved the way to another world and set the course for future space travel.

Nova: Appolo's Daring Mission airs Wednesday, December 26, 2018, at 9 pm on WGBH 2. Watch a preview below.