Dr Jon Ables, an astronomer with the CSIRO Division of Radiophysics, takes us on a tour of the 64 metre radio telescope near Parkes, New South Wales. He points out its main features and explains how observations of distant galaxies are carried out day and night.
[A timer appears on screen, counting down from 15-seconds]
[New text appears: A tour of the Parkes Radio Telescope]
[New text appears: with Dr Jon Ables]
[Image changes to the camera panning down the Parkes radio telescope and shows a white car pulling up with Dr Jon Ables stepping out of the vehicle]
Dr Jon Ables: Well here we are at the Parkes Radio Telescope, today one of the foremost instruments in the world for radio astronomy. It’s a big dish 64 metres in diameter and it can turn and tilt to scan the entire sky.
[Image changes to show the radio telescope in motion with the text: TIME-LAPSE PHOTOGRAPHY]
With it tipped over to the ground like it is now we can step right aboard. Come with me and I’ll show you how it works.
[Image changes to show Dr Ables stepping up into the telescope dish he reaches a landing and picks up a hand held radio to speak to Bob]
OK, Bob take the telescope to the zenith.
[Image changes to show Bob in the control room then to Dr Ables walking across the surface of the dish now pointing directly up]
The radio waves from space striking the surface of the big dish here are reflected and focused to a spot directly over my head. There’s the aerial cabin where the sensitive receiving gear is placed.
[Dr Ables walks up some more stairs and enters a elevator that takes him high up to focal platform of the telescope]
Well here we are on the focal platform itself. Below us there’s nothing but the big dish itself. The radio waves are focused right to this platform. I’m looking onto the dish and I know full well that the radio waves from distant galaxies and quasars and pulsars are being focused right into my face but I don’t feel a thing. The reason is that these waves are extraordinarily weak and that’s what we need this receiver for. It’s a very sensitive amplifier which amplifies the signal about a million times. The signal passes through a hole, not the one I’m looking through, but a hole here in the centre and up through these pipes and into the receiver. From there it’s sent down cables to the radio room which is in the tower supporting the dish itself below us.
[Image changes to an animated radio telescope showing the paths of the signals, reflecting from the dish, into the aerial cabin and then down into the control tower] [Image has changed back to Dr Ables on the ground standing in front of a door]
We’re back on the ground again just outside the supporting tower of the telescope. It has three levels but we’ll pick up our radio signal on the first floor.
[Dr Ables enters through the door and heads up some stairs]
We’re now on the first floor of the supporting tower of the telescope and this room which is often called the radio room is filled with equipment to further amplify the weak signal that was sent down by the cable from the aerial cabin.
[The camera pans over the equipment in the room]
The signal which was already amplified by a million times in the aerial cabin is increased in strength again a million times. And finally a million million times stronger than when it came from space into the telescope it is ready to be sent to the control room above us for final recording and analysis.
[Dr Ables walks up more stairs to the control room]
Now in the control room the signal generally is passed first to this machine. The purpose of this machine is to break the radio signal into its component parts very much like a prism breaks white light into its colours and this machine works with our digital computer. The digital computer finally presents the result as a graph.
[The camera zooms in on the graph being printed from the computer]
And here’s the digital computer and in front of it the radio astronomer. These days to be a radio astronomer often means that you have to be a computer operator as well. How’s it going Alan?
Alan: Well we’ve got a possible detection on 273 but I think we’ll have to leave it for today. I think we’ll go over to 2142. Frank, could we go to 2142 minus 75 please?
Dr Jon Ables: And that was the astronomer telling our telescope driver to move the telescope to the next source in the sky that he wishes to observe.
[Camera zooms in on the radio telescope moving and then moves back to the control room]
Frank: You’re on source Alan.
Dr Jon Ables: The observations of the heavens with the radio telescope continue night and day and the information collected appearing mostly as graphs, charts, tables flows out continuously but eventually it is in the mind of the radio astronomer himself that the picture of the universe must form. The radio telescope serves only to extend the senses of man deeper into the heavens to find out how it works and what our place is in it.
[Images has changed to show control room colleagues in discussion]
Male: Well what do you reckon Paul?
Paul: I think we should do 0922 minus 51 with a ten second integration marker.
Male: Yes, but you’ll have to reload the tape again first.
Paul: Yeah, OK.
[Image changes back to the radio telescope lit up at night. Credits roll: Editing Ron Brown. Sound recording Malcolm Paterson. Photography Roger Seccombe. Directed by Tony Chenn. Produced by the CSIRO Film and Video Centre CSIRO 1979]