A Wind Storm in Australia Nearly Interrupted the Moon Landing Broadcast

Science
سه شنبه 18 تیر 1398 ساعت 23:51
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Smith sonian mag
Fifty years ago this month, 650 million people—one-fifth of the world’s population at the time—gathered in front of their televisions to watch Neil Armstrong and Buzz Aldrin walk on the moon. Though celebrated as an American achievement, those TV images would never have reached the world’s living rooms without the help of a crack team of Australian scientists and engineers, working in the bush a few hundred miles west of Sydney.
The Apollo lunar module had a transmitter for sending back not only TV images but also crucial telemetry, radio communications and the astronaut’s biomedical data—but receiving those signals was no simple matter. The transmitter had a power output of just 20 watts, about the same as a refrigerator light bulb, and picking up that signal from the moon a quarter of a million miles away required huge, dish-shaped antennas. Moreover, as the Earth turns, the moon is only above the horizon for half the day at any one receiving station. So NASA relied on ground stations on three different continents, located at Goldstone, in California’s Mojave desert, in central Spain, and in southeastern Australia. To this day, these radio stations make up the Deep Space Network, allowing NASA to monitor all parts of the sky for communications at all times.
The critical moment when Armstrong and Aldrin were due to leave the lunar module and step out onto the moon’s surface was initially scheduled for noon, eastern Australia time, which would have put the giant 210-foot (64-meter) dish at Parkes, New South Wales, in prime position to receive the signal. A smaller 85-foot (26-meter) dish at Honeysuckle Creek, south of Canberra, was also in position, and another Australian facility, the Tidbinbilla Deep Space Instrumentation Facility (now the Canberra Deep Space Communication Complex), was also supporting the mission by maintaining communication with astronaut Michael Collins, who remained on board the command module in lunar orbit. Goldstone participated too; from California, the moon was low in the southwestern sky, allowing reception of the Apollo signal until the moon dipped below the horizon. Each facility would relay their signal to Houston for distribution around the world.
The Parkes 64-meter radio telescope at the observatory in Parkes, New South Whales, Australia. The dish was used to receive video and communications from the Apollo 11 moon landing on July 20, 1969. (Dan Falk)
But all did not go according to plan. The astronauts, eager to leave the spacecraft, decided to skip their scheduled rest break and began preparing for their moonwalk some six hours ahead of schedule, forcing the Australian antennas to aim just above the horizon, rather than overhead. Because of its design, however, Parkes can’t tilt its huge dish any lower than 30 degrees above the horizon. And to complicate matters, it was just then that the windstorm of a lifetime kicked in, with gusts of 60 miles an hour buffeting the giant Parkes dish.
“Essentially, it’s a glorified beach umbrella—and just like a big beach umbrella, whenever the wind blows, it puts a lot of force on the dish,” says John Sarkissian, an Operations Scientist at Parkes and an Apollo history enthusiast. “When that gust hit, the whole room just went ‘boom’—it just shuddered and swayed.” (Though Sarkissian works at Parkes now, back then he was a six-year-old “sitting cross-legged on a cold wooden floor” in his first-grade classroom in Sydney, watching the historic event unfold on TV.)
Goldstone was picking up the signal, but they had trouble as well: Technical problems resulted in a harsh, high-contrast image; and, worse than that, the image was initially upside down. The TV camera on the lunar lander was intentionally mounted upside down to make it easier for the astronauts to grab in their bulky suits; a technician at Goldstone apparently forgot to flip the switch that would invert the image.
Back in Australia, with the winds howling at dangerous speeds, normal protocols would have called for a halt to telescope operations—but this was humankind’s first visit to another world, and the rules were bent. Parkes director John Bolton gave the go-ahead to keep the dish operating.
Fortunately for the Parkes crew, the astronauts took longer than expected to put on their spacesuits and depressurize the lunar module in preparation for the moonwalk, allowing the moon to rise a bit higher in the sky and align with the big dish’s line of sight. And even more fortunately, the delay allowed the storm to blow over. The wind eventually subsided, allowing the telescope to lock onto the Apollo signal. (The episode is dramatized in the 2000 movie The Dish , starring Sam Neill, which takes quite a few liberties but gets the blustery wind right.)
The Parkes 64-meter radio telescope during the Apollo 11 mission, receiving signals from nearly a quarter of a million miles away. ( CSIRO via Wikicommons under CC BY 3.0 )
Happily, the images from “down under” were right-side up. Remarkably, the inverter switch from Honeysuckle Creek has survived; it was kept as a souvenir by one of the technicians, and eventually donated to the small museum at the Canberra Deep Space Communications Complex.
“I reckon that’s one of the most important switches in history,” says Glen Nagel, an outreach officer at the CDSCC, pointing to a toggle-switch attached to a small circuit board. It’s displayed in a glass cabinet alongside a Hasselblad medium-format camera and other artifacts associated with the Apollo missions. “Without that switch, all of us would have had to have stood on our heads to watch man walk on the moon—or turn our television sets upside down.”
Controllers in Houston could choose which feed to send out to the TV networks, and in the end telescopes in both California and Australia played a role. Viewers around the world saw Goldstone images for the first minute or so of the astronauts’ moonwalk (most of it right-side up, once the switch was flipped); then Honeysuckle Creek images for Armstrong’s first steps on the moon’s surface. Then, just before the nine-minute-mark, as Armstrong starts to explore the lunar surface (and about ten minutes before Aldrin comes down the ladder), Houston switched over to the superior images from the enormous Parkes dish—and remained on Parkes for the rest of the two-and-a-half-hour lunar walkabout.
Most viewers would have known nothing of the windstorm at Parkes—or even of the giant dish that played such a vital role in the historic broadcast.
“I always say, the astronauts may have been on the Sea of Tranquility on the moon, but it was definitely the ‘Ocean of Storms’ here that day,” Sarkissian says.
Neil Armstrong sets up a camera to record the first time humans walked on the moon. (NASA)
The Honeysuckle Creek antenna was shuttered in 1981 and relocated to the Canberra complex, where it stands as a gigantic metal museum piece. Nagle recalls a visit that Apollo 17 astronaut Gene Cernan paid to the site in the spring of 2016 while promoting the documentary, Last Man on the Moon . “He grabbed my arm and said, ‘Glenn, whatever you do, don’t let them take this down. This is our last link to the moon. Preserve this antenna.’” Cernan died early the following year.
Parkes, meanwhile, remains a world-class radio observatory, known for the first detection of Fast Radio Bursts (mysterious bursts of energy from deep space) and for participating in the search for extraterrestrial civilizations as part of the Breakthrough Listen project. The giant dish also continues to track NASA spacecraft , including Voyager 2, now some 11 billion miles (18 billion kilometers) from Earth.
Most of the scientists who work at Parkes today, though too young to remember Apollo, are still keenly aware of the history that surrounds them. As are the townspeople: With a population of just over 10,000, the town and the enormous telescope are just about synonymous.
“The dish is the community, as much as the community is part of the dish,” says Jane Kaczmarek, a staff astronomer at Parkes. “And I think this Apollo anniversary really strikes a chord with the town, because everyone here feels a sense of connection to what was accomplished.”
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