Did you know? - "The Dish"

The Parkes Telescope - “The Dish” - from its historic role in the Apollo 11 Moon landing to looking for ET it has played an important part in Australian astronomy.

The dish is not fixed to the top of its tower, but just sits on it. The moving part of the telescope weighs 1000 tonnes but is not fixed to the tower, instead it sits on top with its own weight holding it down.

Because the large surface area catches the wind like a sail, if the wind exceeds 35 km per hour it must be ‘stowed’ by pointing it directly up. During the Apollo 11 Moon landing it was struck by a series of severe 110 km per hour wind gusts which made the control room shudder. Fortunately, the winds abated and Buzz Aldrin activated the TV camera just as the Moon rose into the telescope’s field of view. The telescope began tracking. Image Courtesy CSIRO.

The selection for a site to build a radio telescope took several years and had to fulfil several technical requirements, such as a stable geology and low radio interference. By 1956, there was a list of over 30 possible locations. The decision was made in favour of Parkes in March 1958.

The telescope has been used to listen for ET. When Project Phoenix - a search for extra-terrestrial intelligence -was launched, researchers from the SETI Institute in California used The Dish for a six-month observation of 200 nearby stars.

A must see for any astronomy/space buff is the 2000 movie The Dish which portrays the role the Parkes Telescope played in the Apollo 11 Moon landing. One interesting morsel of trivia to come out of the movie was the problem the directors had in conveying the sheer size of the dish. They came up with the idea of playing a game of cricket on it, however a real cricket ball would damage and easily dent the surface of the dish. The actors were given a soft tennis ball to use instead.