This is the 20th in an exclusive series of 50 articles, one published each day until July 20, exploring the 50th anniversary of the first-ever Moon landing. You can check out 50 Days to the Moon here every day.
There are many hidden corners of the race to the Moon in the 1960s, vast undertakings that were necessary to get astronauts to the Moon and back but that weren’t glamorous or high-profile enough to get much attention.
One of the most impressive and vital was NASA’s creation of a global tracking and data network to track the astronauts to the Moon and back, to get data and instructions to them and their spacecraft, and, of course, to talk to them and receive data and TV broadcasts from space.
It was a daunting project. To maintain contact with a spaceship 100% of the time, there had to be tracking stations—big antennas—located in just the right places, so communication could be maintained as the Earth turned and as the spaceships themselves rocketed to the Moon, orbited it, and then returned home.
To be useful, those far-flung stations had to be connected to each other—and to NASA officials back in the U.S.—with a fail-safe data network. Special attention had to be paid to the hours after launch and during splashdown, when critical events might happen out of reach of even the land-based tracking stations.
The antennas had to be able to pinpoint the relatively tiny spacecraft—docked together, the command module, service module, and lunar module were just 53 feet long, as long as a truck semitrailer—at a distance of 240,000 miles. They had to maintain their lock on the spacecraft while they were headed to the Moon, in orbit around it, and on the surface.
The whole thing had to be staffed 24 hours a day, in every time zone around the world.
Even with the tools of 2019, setting up such a network would be wildly ambitious. With the computer and communications technology available in 1965, creating it was an effort that was a microcosm of the larger challenge of getting to the Moon.
As constructed and operated during Apollo, the network—NASA called it the STDN, the Spaceflight Tracking and Data Network—had 14 big antennas in sites ranging from Bermuda to Madrid to Guam. The three largest antennas, still in use, have surface areas two-thirds the size of a football field, tilted up in the air, aimed at the signals coming from Apollo.
STDN also had four specially constructed ships at sea—oil-tanker hulls hollowed out and retrofitted with huge tracking antennas, mounted bow to stern—and two satellites to help relay signals. During splashdown, as the capsules floated to the Pacific Ocean on parachutes (well beneath the range of land-based tracking antennas), NASA put eight airplanes aloft to maintain communication.
The tracking stations were linked by two-million miles of communication links: telephone wire, undersea cable, microwave towers. That’s enough communication line to circle the Earth 80 times, and it was the first global, high-speed data network. The system was designed and run by NASA’s Goddard Spaceflight Center in Maryland, just outside Washington, D.C. That’s where all the signals were collected from around the world and then piped from Goddard to Mission Control in Houston. They went back out through Goddard as well.
The network cost $370 million to assemble in the mid-1960s. For comparison, each lunar module cost about $100 million. It required 2,700 people to operate and relied on 39 Univac computers spread around the world to manage the signals pouring in. During the Apollo years, it cost $70 million a year to run. The phone bill alone, the cost of those two million miles of leased communications lines, was $50 million annually (almost $400 million in today’s dollars).
The communication speeds were good for 1969, although what’s amazing is what NASA was able to do with what seems today to be a trickle of data. Coming down from the spacecraft, the data rate was 51,200 bits a second. Going back up from Houston to the astronauts, the rate was 2,000 bits per second. The critical dedicated data link between Goddard and Mission Control ran at 40,800 bits a second at a time when we were still almost three decades away from home-based modems that could match and exceed that bit rate.
The pictures from Apollo 11, that first Moon landing, streamed in first to the Honeysuckle Creek antenna in Australia. That’s where the images of Neil Armstrong stepping off onto the lunar surface came back to Earth. Twenty minutes later, when Buzz Aldrin came down the ladder, the Earth and Moon had shifted positions enough that the pictures of Aldrin came back through the next station in the network, Parkes Observatory, also in Australia.
Australia’s role in the data network—bringing home the signals, voices, and TV images from the first Moon landing—was such a point of pride and drama that it inspired the (mostly true) 2000 movie The Dish, starring Sam Neill, which was well received in both the U.S. and Australia. It also inspired a 527-page history from NASA with the spirited title Read You Loud and Clear.
The global tracking network didn’t just work: it was one of the quiet marvels of the early space age.
STDN’s navigational fixes were so accurate and could be calculated so quickly that at most points during the Apollo missions, the best navigation data for the astronauts didn’t come from their own ships and onboard navigation instruments but back up from the ground.
In lunar orbit, 240,000 miles from Earth, the NASA tracking network could pinpoint the location of the command module and the lunar module to within 30 feet (0.006 miles) and could clock their speed to within 1 mph.
NASA had created an intergalactic radar gun.
Charles Fishman, who has written for Fast Company since its inception, has spent the past four years researching and writing One Giant Leap, a book about how it took 400,000 people, 20,000 companies, and one federal government to get 27 people to the Moon. (You can order it here.)
For each of the next 50 days, we’ll be posting a new story from Fishman—one you’ve likely never heard before—about the first effort to get to the Moon that illuminates both the historical effort and the current ones. New posts will appear here daily as well as be distributed via Fast Company’s social media. (Follow along at #50DaysToTheMoon).