The Parkes feedhorn and the Apollo 11 Moon Landing
By Sarah Reeves
Slowscan TV camera footage showing astronaut Neil Armstrong as he climbs down the ladder of the Apollo lunar module to become the first human to step foot on the Moon. Image: NASA.
Today, Friday 21st July 2017*, marks 48 years since Neil Armstrong became the first human to set foot on the moon, uttering the now-famous words "That's one small step for man, one giant leap for mankind". Though there has been much debate in decades since about whether Armstrong might have fluffed his line or been misquoted, there is no doubting the historical significance of this moment.
What is less known, however, is the role that the small town of Parkes, NSW, played in this momentous event, and the piece of Apollo history that is now preserved in the MAAS collection. Parkes is home to the Parkes Radio Telescope 'The Dish', a huge 64m dish-shaped structure designed to detect faint radio waves from space. As an astronomical observatory, The Dish studies all kinds of exotic objects from pulsars, rapidly spinning star cores that emit jets of radio emission from their poles, to the hydrogen gas that permeates our entire Galaxy and provides the raw fuel from which new stars are continually forming.
The Parkes Radio Telescope, commonly referred to as 'The Dish', which was responsible for receiving the famous TV footage of the moonwalk. Image: CSIRO.
In 1968 John Bolton, the then Director of Parkes Observatory signed a one-line contract with NASA, stating that "The [CSIRO] Radiophysics Division would agree to support the Apollo 11 mission", by becoming one of the official tracking stations. There were numerous other stations involved around the world, which together provided 24-hour communication with the Apollo 11 spacecraft, and the lunar module that descended to the surface.
The location of the Apollo 11 landing site. Image: Soerfm, CC BY-SA 3.0, Wikimedia Commons.
When Armstrong and fellow astronaut Buzz Aldrin took their first steps on the moon the world was watching, and The Dish was one of three stations simultaneously receiving the TV signals – along with the Honeysuckle Creek station just outside of Canberra and NASA's Goldstone station in California. Originally designated as a backup station, Armstrong's decision to ignore a planned rest-break meant that – by the time the astronauts had donned their cumbersome space suits – the moon was just rising at Parkes, putting The Dish in the prime position to receive the awe-inspiring footage.
In the first minutes of the moonwalk, NASA switched between Honeysuckle Creek and Goldstone, trying to get the best picture. But when the moon rose high enough to be visible from Parkes, the larger dish gave such superior quality that NASA switched the picture to Parkes, staying with them for the remainder of the 2.5 hour broadcast. Throughout the broadcast the telescope battled dangerously high winds, but somehow managed to stay locked on the Moon, delivering the images we all know and remember. The incoming radio waves, which carried the TV signals, bounced off the surface of the dish and were reflected up to the feedhorn and receiver at the focus. From there they were sent to Sydney for broadcast to Australia and the rest of the world.
The 'Apollo feedhorn' which sat at the focus of the telescope, and funnelled the radio waves carrying the TV signals into the telescope receiver before being broadcast to the world. Image: CSIRO.
The full, dramatic story of Parkes' involvement in the Apollo 11 mission later became the subject of the classic Australian movie, The Dish. The 'Apollo feedhorn' was donated by CSIRO to the Museum in 1997, when the Parkes telescope was upgraded, and can now be seen on display at Sydney Observatory.
*The landing took place on 20th July in the USA, but at 12.56 pm AEST on 21st July in Australia.
Written by Sarah Reeves
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