How engineers (and astronauts) made Apollo 8’s ‘Earthrise’ possible 50 years ago

Earthrise

Earthrise

Apollo 8’s astronauts were the first to witness Earthrise from lunar orbit, on Christmas Eve in 1968. (NASA Photo / Bill Anders)

It’s been 50 years to the day since Apollo 8 astronaut Bill Anders’ “Earthrise” photo changed our world forever, but that mission to the moon and back wouldn’t have happened the way it did if it weren’t for a giant leap in technology.

That comes through loud and clear in “Apollo’s Daring Mission,” a NOVA documentary making its debut on public television on Wednesday.

“NASA usually went step-by-step. In this case, they jumped three or four steps,” the 85-year-old Anders, who now lives in Anacortes, Wash., says during the show.

The Apollo 8 story usually spotlights the impact of Anders’ photos, which were the first to show our planet hanging over the moon’s surface, and the magic of the crew’s Christmas Eve reading from Genesis. Those moments get their due in “Apollo’s Daring Mission.” But the show focuses primarily on the engineering magic that opened the way for history to be made in 1968.

Apollo 8 wasn’t supposed to go to the moon. It was originally meant to be an initial crewed test of NASA’s Saturn V moon rocket and Apollo command module in Earth orbit, following Apollo 7’s test flight with the less powerful Saturn 1B launch vehicle.

But CIA imagery suggested that the Soviets were preparing to send cosmonauts on a flight around the moon in late 1968 or early 1969. That led NASA planners to abandon their step-by-step plan and consider sending Apollo 8’s astronauts — Anders, Jim Lovell and mission commander Frank Borman — on their own round-the-moon trip. (The fact that the Apollo lunar module wasn’t yet ready for testing was another factor behind NASA’s plan.)

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Could the Saturn V and the Apollo spaceship be ready in time? The NOVA program traces how engineers had to tweak the design of the Saturn V’s F-1 rocket engines to make sure they didn’t blow themselves apart due to combustion instability. “The solution had to come by trial and error,” rocket engineer Sonny Morea recalls.

Adding baffles to the F-1’s injector plate turned out to be the key to dampening the instability. NOVA’s animation makes clear why the solution worked. (You’ll get your chance to see the baffles themselves at Seattle’s Museum of Flight, courtesy of Amazon billionaire Jeff Bezos’ F-1 engine recovery effort.)

Engineers had to devise an inertial navigation system that worked for the Earth-to-moon trip, with corrections made by eyeballing the stars through a space sextant.

And they had to create the first real-time embedded computing system, controlled by punching codes into a display keyboard. “Apollo’s Daring Mission” shines a well-deserved spotlight on MIT software engineer Margaret Hamilton, whose leadership of the programming effort earned her a Presidential Medal of Freedom (and her own Lego minifigure).

Apollo 11 astronaut Mike Collins gets a turn in the spotlight as well, by virtue of his role as Mission Control’s capsule communicator. He was the guy who told the Apollo 8 crew on Dec. 21, 1968, that they were cleared to leave Earth’s orbit and head for the moon, a milestone known as trans-lunar injection or TLI.

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“I just wish I really had that moment to live over again,” Collins says, “because I would have said to them, ‘Apollo 8, you can now slip the surly bonds of Earth and dance the sky, Apollo 8. Dance the sky! You go!’ ”

Go they did, and “Apollo’s Daring Mission” retells the tale of the engine firings that had to work perfectly, behind the moon and out of contact with Mission Control, in order to put the command module into lunar orbit and eventually send it back toward Earth again.

During the 20 hours or so that separated lunar arrival and departure, Apollo 8’s crew took pictures surveying the moon’s surface for future landing sites. In the middle of their survey, Anders looked up from his camera and became the first human to marvel at the sight of Earth rising over the moon’s horizon.

“Oh my God, look at that picture over there,” Anders said, turning the camera. “There’s the Earth comin’ up. Wow, is that pretty!”

“Hey, don’t take that, it’s not scheduled,” Borman joked.

But Anders did take the picture, first in black-and-white, and then in color. For a detailed recreation of the Earthrise experience, augmented by modern-day imagery from NASA’s Lunar Reconnaissance Orbiter, check out this video from NASA’s Goddard Space Flight Center:

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The iconic Earthrise shot put our pale blue dot in cosmic perspective as no previous picture could, and gave rise to a phenomenon known as the “Overview Effect”: a deep feeling of connectedness, accompanied by the sense that protecting Earth should take priority over society’s petty divisions.

“We came all this way to explore the moon, and the most important thing is that we discovered the Earth,” Anders said after the mission.

But Earthrise wasn’t Apollo 8’s only legacy. “This is the moment that the Space Race ends,” engineer-historian David Mindell, author of the book “Digital Apollo: Human and Machine in Spaceflight,” says during the NOVA show.

It turned out that the CIA was right about the Soviets’ intentions, but due to technical problems, their crewed round-the-moon mission couldn’t make its planned launch date in early December 1968. After Apollo 8, and after the Apollo 11 moon landing that came seven months later, the Soviet moon program fizzled out.

Mindell also argues that Apollo 8 set the stage for America’s primacy on another technological frontier. “Now, we have digital computers in everything,” he explains. “This was the first digital computer in almost anything.”

Fifty years later, the digital revolution is fueling another golden age for space commerce and exploration. There’s no way commercial space ventures such as SpaceX and Blue Origin could do what they’re doing without advanced software tools, plus the frontier-pushing mindset that has guided the careers of Elon Musk, Jeff Bezos and so many others.

More than Earthrise, Apollo 8’s legacy of technological innovation is what will take us back to the moon, this time to stay — and push us onward to new horizons.

“Apollo’s Daring Mission” makes its debut on PBS stations on Wednesday. Check local listings for times. For another take on the Apollo 8 mission, check out “Earthrise,” a 30-minute film by Emmanuel Vaughan-Lee.

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