“One giant leap”

The infamous wind storm on the Parkes horizon during Apollo 11. This is the only known photograph of the storm.

The infamous wind storm on the Parkes horizon during Apollo 11. This is the only known photograph of the storm. Credit: David Cooke

Parkes’ role upgraded

The original mission plan had Parkes as a backup to the 64-metre dish at Goldstone and the 26-metre dish at Tidbinbilla. The astronauts were to walk on the Moon soon after they landed the lunar module, completing their activity before the Moon rose at Parkes. Parkes would step in if the moonwalk was delayed and the Moon had set at Goldstone. The Honeysuckle Creek antenna was to track the Command Module, Columbia, which would be orbiting the Moon, while Tidbinbilla was to follow the lunar module, which would descend to the Moon’s surface.

Two months out from the flight, there was a change of plan. The astronauts were now scheduled to rest for a few hours after they had landed. This meant that the moonwalk would start about 10 hours later, when the Moon would have set at Goldstone but be high overhead at Parkes. Parkes was upgraded from backup to prime receiving station for the TV broadcast.

The day after Apollo 11 launched, a fire at Tidbinbilla damaged that station’s transmitter. Repairs were quick but NASA was nervous. Tidbinbilla’s role was switched with that of Honeysuckle Creek. Now Tidbinbilla would follow the command module in orbit and Honeysuckle would focus on the lunar module.

“One giant leap”

On the day of the moonwalk, events departed from the script.

Astronauts Neil Armstrong and ‘Buzz’ Aldrin landed the lunar module on the Moon at 6.17 am AEST, Monday 21 July.

Dismissing the idea of rest, Armstrong opted to get started on the moonwalk. But the astronauts took hours to struggle into their spacesuits and depressurise the module.

By the time they opened the door, the Moon was just rising at Parkes. The telescope was tipped right over, looking to the horizon, when it was hit by two sharp gusts of wind. Acting like a giant sail, the dish was feeling force ten times greater than was considered safe. Its tower shuddered and swayed as the wind alarm rang out in the control room. Just as the Moon rose into Parkes’ view, the wind slackened.

Parkes staff watch the moon landing.

Parkes staff watch the moon landing. Credit: CSIRO

Aldrin flipped the switch on the TV camera and the broadcast began.

Goldstone, Honeysuckle and Parkes were all receiving signals, Parkes at first with its less-sensitive ‘off-axis’ detector and then – eight minutes later as the Moon rose further – with its main ‘on-axis’ detector.

The signals were sent to Sydney via specially installed microwave links. Here a NASA officer chose between the Parkes and Honeysuckle Creek signals, relaying whichever looked better to Houston. In Houston a controller selected the signal for the international broadcast, choosing between those from Goldstone in California and the ones sent from Australia.

For almost the first nine minutes of the broadcast, NASA switched between signals from Goldstone and those from Honeysuckle Creek – the latter capturing the first footstep on the Moon.

Eight minutes and 51 seconds in, the signals from Parkes’ main detector came through. These were so good NASA stayed with them for the rest of the two-and-a-half-hour broadcast. But the weather stayed bad at Parkes and the telescope operated outside its safety limits for the whole moonwalk.

Following this success, NASA contracted Parkes to help track Apollo 12 and 15. Parkes was also brought into NASA’s Manned Space Flight Network when an accident occurred during Apollo 13.

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Parkes receiving”: a CSIRO documentary about the Parkes’ radio telescope’s role in Apollo 11. Produced in 1969, it contains a montage of many scenes and interviews recorded one week earlier during the press visit on 14 July 1969, and during the moonwalk on 21 July 1969.