The Parkes Observatory is a radio telescope observatory, 20 kilometres north of the town of Parkes, New South Wales, Australia. It was one of several radio antennas used to receive live, televised images of the Apollo 11 moon landing on 20 July 1969.
Australia got off to a good start in radio astronomy just after the Second World War. Staff of the CSIRO Radiophysics Laboratory (later the Division of Radiophysics) made the first Australian efforts.
The first proposal was to build a large air-warning antenna that would double as a radio telescope. The Radiophysics Laboratory had close links with the Royal Australian Air Force (RAAF): during the war it had worked for the army, navy and air force and just after the war it was advising the RAAF on radar and navigation equipment, including air-warning equipment. But the RAAF was even more strapped for cash than CSIRO, and had no money to put towards such a project.
In 1952 it became clear that CSIRO too had no chance of getting a large capital sum to fund such an instrument. Some way had to be found to squeeze it out of the existing Radiophysics budget. So a proposal was drawn up for a cylindrical antenna, lying on its back, 1000 feet long and 200 wide, made up of five adjoining elements. Each element would be 200 feet square, lying on an east-west line and scanned by cable and
winches in the north-south direction. The total cost was to be about £A125 000, spread over five years. But once again the answer was ‘no’.
US support, Now a new factor appeared. Unlike Australia, the USA had been slow to take up radio astronomy after the Second World War. The leader of the Division of Radiophysics, Dr E. G.
Bowen, had many contacts in science and industry in the USA, and he urged them to help the USA to take up radio astronomy, mainly by building a large radio-receiving antenna.
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Government Support, The last hurdle was that the overseas bodies required that their own grants be met, dollar for dollar, by the Australian Government. The Government rose to the occasion and contributed to not only the capital costs but the running costs as
well. A year later the Rockefeller Foundation gave a further $US130,000. The telescope now had an assured future.
At that time there was no-one in Australia capable of building the Parkes telescope or even doing the engineering design. So CSIRO went to Britain for advice (it was thought to be cheaper than the USA). The first person consulted was Barnes Wallis (of ‘dambusters’ fame), who was then the Chief Engineer of Vickers. He advised on the problems of deflection of the telescope’s structure, first by thinking of incompressible columns (he held the patent to this device) and then by recommending automatic compensation for changes to the dish's parabolic shape (which was in fact used in the telescope). In a significant departure from the design of previous telescopes, Wallis recommended that the telescope’s mounting system (the way in which it is turned and pointed to different parts of the sky) be 'alt-azimuth', rather than, for instance, the equatorial mount used on the earlier radio telescope at Jodrell Bank in the UK. And just for good measure, Barnes Wallis came up with the idea of the telescope’s guidance system, the 'master equatorial'. Wallis’ contributions far exceeded his very small retaining fee – which, in any case, it seems that he was never paid.
The detailed engineering design for the Parkes telescope was done by Freeman Fox, the company that had designed the
Sydney Harbour bridge. The design contract was placed in 1956 and completed in 1959. After this came the search for a construction contractor: CSIRO settled on the MAN Company (Maschinenfabrik Augsburg-Nurnberg A.G.) in Germany. The contract was placed in 1959 and the telescope completed in 1961.
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Telescope statistics
•Diameter of dish: 64 m
•Collecting area of dish: 3216 m2
•Height to top of focus cabin: 58 m
•Focal length: 27.4 m
•Weight of dish: 300 tonnes
•Weight above control tower: 1000 tonnes
•Maximum tilt: 60° from the vertical
•Time to maximum tilt: 5 minutes
•Time for 360° rotation: 15 minutes
•Surface accuracy: 1–2 mm difference from best-fit parabola
•Pointing accuracy: 11 arcseconds rms in wind (about the width of a finger seen 150 m away)
•Maximum operating wind speed: 35 km per hour
•Motors: 4 x 15 hp 480 volt DC
•Gear ratios – 40,000 : 1