Return to Green Bank
Grote Reber
moved to Tasmania
for further radio telescope experiments
transcript from http://www.abc.net.au/radionational/programs/inconversation/the-father-of-radio-astronomy/3255178
The late Grote Reber is recognised as both the father of radio astronomy and the first person to build a big dish telescope to explore the cosmos. The American moved from his home in the USA to Tasmania in the 1950s and assisted this country to establish a lead in the field. Now a museum has been opened by the University of Tasmania to commemorate his work and David Fisher takes us on a tour with astronomer Professor John Dickey
Robyn Williams: Good evening, Robyn Williams with another conversation, this time coming from Hobart and featuring John Dickey with my colleague David Fisher. But before we join them a question. You know the film The Dish starring the grand old lady the Parkes Telescope which helped bring the world the first steps on the moon back in 1989? Well, who invented those dishes for capturing radio waves from outer space? His name is not well known, partly because he was a bit of a recluse and partly because he chose to keep away from the better-endowed centres in America and Europe. I'm talking about Grote Reber who came in Australia in the 1950s and died in 2002. And now there's a brand new museum to display his genius.
John Dickey and David Fisher take us on a tour.
John Dickey: Well the first thing I want to point out is the construction of the museum itself. Grote Reber's original telescope which he built when he was living in America is now under National Register of Historic Structures in the US and it's on display in Greenbank, West Virginia at the National Radio Astronomy Observatory. His second great telescope was the one he built at Bothwell in Tasmania which was a huge array of poles and wires, a square kilometre altogether in area. Unfortunately that should really be a historic structure as well but it's fallen down and it's no longer in existence.
But the one bit of it that we do still have is the control building, that is to say his radio shack or his shed from which he controlled and in which he sat when he was observing. So we have that, we got the structure moved here to Mount Pleasant to the observatory and then our objective in building this museum was to work out a way that the general public could visit, learn about Grote Reber, see the inside and outside of his radio shack because it's a historic structure and also nave a nice time. That is, not just peek at from outside but really walk around and learn about him.
Because it's such a certain structure we couldn't change it in any way, we couldn't even drill holes in the wall or anything. So we've built the museum to adjoin the radio shed and if you look around here you'll see that the roof overlaps but doesn't actually touch and the walls abutt but they don't actually touch in any way.
David Fisher: Yes, it's completely separate.
John Dickey: It's completely separate but it's easy to walk into it from the museum and to see all the stuff that he had in it. The reason that he moved here to Tasmania in 1954 is that our magnetic latitude is almost unique in that there is only two places in the world with the same magnetic latitude as here Tasmania and Northern Canada. Northern Canada is not a very benign place to live so he chose Tasmania. And the reason that magnetic latitude is important is that he was observing at frequencies where the radio waves don't penetrate through the ionosphere except at those particular places where the magnetic field is going straight up from the surface. So there are places like that on the earth and Tasmania happens to be one of them.
David Fisher: So the incoming signals get a clear run?
John Dickey: So the incoming signals get a more clear run, it's not perfect but it makes some difference, yes.
David Fisher: So here he is, a mannequin of Grote Reber and with his original equipment, a light going on there and I see he's got headphones on.
John Dickey: Yes. In the radio shed he never had any electric power so we got for example his old gas powered lamp, we got some of his radio equipment. Here you can see exactly how he would have looked when he was observing, we have photographs of him when he was observing so we were able to reconstruct that pretty well.
David Fisher: Do radio astronomers use headphones today?
John Dickey: We don't usually use headphones. I've known some radio astronomers who love to put on headphones and listen to the signals. Most of the time the signals that we detect sound like a hiss and so there's not much to get. I think the reason that Grote did use headphones is that growing up with radio astronomy, he was the first radio astronomer, he was working at low frequencies where you really can identify sources of interference by what they sound like. The real signals are still just a hiss but the interference which might be lightening strikes, or might be an aircraft, or a car engine, those things make very distinctive sounds and if those are dominating what's coming into the receiver then you want to reject that data. And I think that's why he probably always wore headphones.
David Fisher: Now Grote Reber has been considered a genius, why is that?
John Dickey: Well he was clearly a genius, if only because of his very broad basic contributions. But his most important contribution was the invention of the radio telescope which is a large parabolic mirror, focusing the radio waves up to a receiver.
David Fisher: Why are you giving this so much prominence, I mean Newton had parabolic discs, what did Grote Reber do to forward the use of a parabolic dish?
John Dickey: That's a very insightful comment. Isaac Newton did invent telescopes which had a parabolic mirror rather than just lenses that you look through and so to that extent what Grote was doing was applying that design, the reflecting telescope design of Newton's to the radio waves. But I think what was the most extraordinary contribution there was that Grote simply realised you could collect radio waves from space in the same way that an optical telescope collects light from space. And that was something that no one had hardly conceived of before, no one had thought of how best to do that. People have thought a lot about how best to do that in the 75 years since but no one has really come up with anything better than the steerable paraboloid design which Grote Reber himself built.
David Fisher: Now I suppose this is the centrepiece of the museum and that is a model of his telescope?
John Dickey: We are very proud of that yes, I think it is a 1 to 5 scale model of Grote's original telescope which is, as we said before, is a large parabola dish parabolic reflector mounted at the focal point is a feed; that is to say it is a antenna which collects the radio waves. Grote invented something called the cavity backed dipole which is now the standard design for all radio telescopes. That was I think never thought of before he first built the first one in 1937.
David Fisher: Tell me a little more about Grote Reber the personality, what do we know about him?
John Dickey: Well I met him only once, he has some friends who are still here in Tasmania who knew him quite well. He was kind of a loner, he worked at times in big organisations like the National Bureau of Standards but I think he was more creative and more successful when he was working mostly on his own. He did have students at the University of Tasmania, he worked with professors at the University of Tasmania at various stages but his greatest contributions I would say he made working alone.
So in a way I think it's fair to say Grote Reber is the quintessential example of the truth that we often forget which is that one person can make a huge difference in history. One person working alone you don't necessarily have to work through a huge institution. Most people do of course work through various institutions of one kind or another but Grote Reber was an exception to that rule.
David Fisher: Now here is an amazing car with wheels that look like bike tyres and it's a little metallic cabin for one person and a roof that flips up.
John Dickey: Yes. Grote Reber was interested in everything and certainly a great many things besides radio astronomy. One of the subjects that fascinated him was transport. Way back in the 60s he realised that a petroleum power transportation system like our modern automobiles would not be able to go on forever. Eventually we would have to run out of petrol, we are not quite at that point yet but we are beginning to feel the limits. He was 50 years ahead of his time in that sense. He realised that electrical power would be something that would be renewable and we could design a whole transport system based on that. So he built bicycles and finally this car, which is powered by electricity, it has batteries in it. The best battery technology of his day unfortunately meant that it was pretty heavy and today I think you could build a car like this which would be even much more effective. But he used to drive this around Sandy Bay, Tasmania, when he was living there.
David Fisher: Really, what's it made from?
John Dickey: It's made of aluminium; it was made by an aerospace corporation in American and was tested in a wind tunnel by them for free. Grote was good at getting people to do interesting things more or less at cost, without having to pay a lot, and the company, I think it was Grumman that build this and tested it in the early 60s, did it in part just out of interest for their own work.
David Fisher: And there's a bicycle here as well but that's not electric is it?
John Dickey: That's powered by gasoline, petrol and he was very interested in making petrol engines more efficient, particularly for bicycles, so he had three bicycles which he fitted with petrol motors at different times and we have one in our museum here and we have his all-electric car which he called Pixie.
David Fisher: Now over here we've got some, these just look like normal fluorescent tubes, why are these in the museum?
John Dickey: They are fairly old-fashioned normal fluorescent tubes from a kitchen lamp which was on the ceiling of his kitchen. Grote Reber meticulously documented all the data from his life, not only his scientific data but every bit of his life. So for example he knew that the fluorescent lamps were guaranteed for a year and he carefully recorded the date that he put them in and the date he took them out over a span of some 20 years. So we have boxes and boxes, he didn't throw them away after that, he kept them for the sake of the data for the lifetimes that he was recording.
David Fisher: And claiming on guarantees no doubt?
John Dickey: Well he was a very careful purchaser let's put it that way. He would always strive to save money on everything, which I think might have gotten compulsive for him at the end but at the same time we can all look up to that. He got his money's worth, let's put it that way.
David Fisher: What else was he documenting, what other elements of his life was he documenting?
John Dickey: Well he documented pretty much everything, I have not seen myself but I have been told that on the wall of his toilet he documented even the frequency and the duration of his own body movements. This is some of his equipment that we found.
David Fisher: Reading glasses...
John Dickey: Notice that he used his pencils right down to the stubs, then he didn't throw them away he saved them for I don't know what -- firewood or something.
David Fisher: He did work in botany as well?
John Dickey: Yes, he worked with bean plants, he was interested in almost everything you could imagine and he made significant contributions to many different fields. I think he had something like 70 publications at the end of his life in something like 50 different journals, so unlike most scientists today he was not a narrow specialist, he was interested in everything. He got interested in some of the Aboriginal archaeological sites here in Tasmania and he was the first person to radio carbon date the ashes left over in some of those sites.
At the time most people thought that the Aboriginal sites were just a few thousand years old but the radio carbon dating of some of the sites down on the Tasmanian peninsular went back 40,000 years ago and that completely revolutionised archaeology of Aboriginal sites here in Tasmania and in many other parts or the world too. A lot of other people started doing it after they saw how he did it.
These are the great radio telescopes of the world which -- you may have visited some and I hope you'll visit more. Ceduna in South Australia belongs to the University of Tasmania and Mount Pleasant here in Tasmania. In order to do very long baseline interferometry we need many telescopes spread widely. In the northern hemisphere there are dozens of radio telescopes, hundreds. In particular for example the international VLBI service which is not just an astronomical service but a service to the entire civilisation by carefully measuring what's called the international celestial reference frame, the far away centres of galaxies which are bright radio sources and provide us with markers with which we define a coordinate system. That is to say X, Y and Z system far beyond the earth, these are things beyond even our galaxy.
In order to define positions on the earth we need to define them relative to that reference system. The global positioning satellite system GPS and also the GNSS, which is a new European system, these all depend on a coordinate system with which they can fix the orbits of the spacecraft which are then transmitting signals down. So whether it be for commercial use or individual civilian use, or navigation at sea, or for hiking in the bush, all of these things ultimately come down to the work that we do here on the international VLBI service.
David Fisher: VLBI refers to?
John Dickey: VLBI means very long baseline interferometry, the I is the important letter there, the interferometry means bringing signals together from several different antennas. So the antenna at Hobart works together with an antenna in Concepción in Chile, with an antenna in Hartebeest Hoek in South Africa and with antennas in Hawaii, Japan, China, North America, Europe, Russia and so on.
However, unfortunately the international VLBI service, which is an international collaboration in order to establish a reference frame from the earth, this is completely dominated by the northern hemisphere. There are some 37 telescopes in the northern hemisphere which contribute. There are only four which contribute reliably in the southern hemisphere. We think that that has to change in particular for Australia's national benefit, national interest. We need to have a better definition of the celestial reference frame in the south where the northern hemisphere telescopes can't see it.
So we are actively working on building new telescopes primarily dedicated to this reference frame. We'd like to put one in Yarragadee in Western Australia and one near Catherine in the Northern Territory in addition to our one here in Hobart and one in Ceduna in South Australia. I think with those four stations we can establish the Australian continent as a plain, and then we can watch how that plain moves -- either due to continental drift or sea level rise due to global warming. It's important for us to get very precise locations established in this way.
David Fisher: There's the proposal, there's the dream you've outlined, what are the dollars?
John Dickey: We can do it fairly inexpensively I think. To put up a telescope in a new site costs a bit under a million dollars Australian so it would be, let's say, $800,000 or $900,000 and that would cover both the antenna, the receivers, the clocks that we need -- we need very accurate clocks -- and also the site preparation and any kind of engineering work that we need.
David Fisher: It doesn't sound a lot for a huge structure, I mean it's something big that people can see way in the distance -- that's a big telescope -- roughly a million does not sound a lot.
John Dickey: Well I hope when you see one in the long distance it makes you feel good because what we're doing is astronomy in the same sense that optical astronomers have done for centuries. And the purpose of our astronomy is to understand our place in the universe, essentially to understand the human condition in the sense of who are we and where are we?
David Fisher: Sure, and you've just mentioned a handful of applications there in the bigger, bigger questions but also climate questions and how the world is changing around us. A million or two for a few more dishes doesn't sound too much.
John Dickey: Well that is something I'd be interested in your opinion of, and the opinion of all your listeners. But I think curiosity driven research, which is always what has motivated scientists going back centuries, often leads to unexpected applications which can be of tremendous value to society, but which aren't what the people set out to do in the beginning.
David Fisher: Yes, they weren't in the original proposal.
John Dickey: Precisely. So although radio astronomy was begun by Grote Reber as purely a curiosity driven thing -- he wanted to see what was out there -- and most of us who do radio astronomy are driven by exactly the same kind of curiosity, we just want to know what makes things work out in space. But those discoveries that we make can have completely unexpected and even unrelated applications here on earth, either to medical research or to positioning and things like that, to agriculture, to navigation. You never can predict what science will lead to but it's important to do it.
I wanted to just point out this dish over here, this is a 14-metre dish which was originally built way back in the early 70s and it was our first parabolic radio telescope here at the University of Tasmania. We've recently gotten a grant from the Australian Research Council to refurbish it, that is to resurface it, and you can see the sun glinting off the brand new surface. We spent the whole of last year, we took it all apart, we tore off the old surface, put on these panels which are made of aluminium which are much more accurate parabola, and we hope to have it back, up on its mount and we will be taking data with it by, I guess, April.
David Fisher: What's the body of water here?
John Dickey: Oh this is the Cole River Valley, yes this is a very beautiful site that we have here, the Cole River flows down through Richmond and then out into the Bay of Storms near the airport, near the Hobart airport.
David Fisher: Well the dish is way on its side now, very different to just 10 or 15 minutes ago.
John Dickey: Pointing west now. When a telescope tracks it follows the radio source as it moves across the sky. If you heard that noise it's now repositioning itself just a little ways off the source. We typically do differential measurements meaning we point out the source and then we move maybe a degree or half a degree off and take the difference of those in order to get the strength of the source.
David Fisher: Now here is something called a whisper dish, so we've got two dishes measuring roughly, what, two metres in diameter?
John Dickey: Yes, that's about right. These are actually old satellite communication dishes. We brought these to service antennas for the GPS receivers that we have here for locating our position and we set them up for kids to play with and we can play with it right now.
David Fisher: Let's be kids.
John Dickey: OK good, I'll go down to the other one if you want to stand here and eventually what you'll do, first put your ear here and you can click your mouse here, or you can put the microphone there and we'll see how it works.
David Fisher: Fine. So John Dickey is walking up the concrete path and the other dish is up there roughly 30 or 40 metres away and we've got the dish set on its side and there is a metal pole with a ring presumably at the focus of the dish. Now John is standing next to the far dish and he's going to speak to me now
John Dickey: Now I'm talking with the same volume that I was using before, but now I'm going to talk very softly, almost as if I was whispering in your ear -- can you hear that?
David Fisher: Well I can hear it yes, it's quite amazing, it's as if you're right here, you're actually still 30 metres away, I suppose you're hearing me as well up there?
John Dickey: I can hear you very well.
David Fisher: So that's John 30 metres away and now he's walking back and it really sounded as if he was right here -- what an excellent demonstration of how dishes work collecting, be they light, be they collecting radio waves, or in this case sound waves and focusing them to a point.
John Dickey: That's right. Both radio waves, light waves, sound waves -- they all propagate as waves, and so the same design technology that we use for one we can use for another, and that's one of the ways that astronomy tends to have spin-off applications in other fields, because we develop things which can be applied to so many different areas. In fact even I think broadcasters were using dishes like this in order to pick up sounds from far away. I remember hearing that in the States they were using them for football games but then they had to discontinue it because some of the language wasn't really the sort of thing you'd want to broadcast.
Robyn Williams: Heaven forfend. That was Professor John Dickey, who is head of maths and physics at the University of Tasmania, playing cosmic cooee with my colleague David Fisher. And by the way you can see part of the structure on the left side of the aircraft as you are about to land in Hobart. Both were at the Grote Reber Museum in Cambridge just outside the capital of Tasmania. David normally produces the Science Show with me every week. Next week at this time I shall be In Conversation with vet Paul McGreevy to discuss his book about Carrots and Sticks -- how best to train animals from border collies to the odd octopus, friendly pats or stern smacks, which works best. Production as ever by Kyla Slaven, I'm Robyn Williams.
Guests
John Dickey Professor Astronomy School of Maths and Physics University of Tasmania