Six decades on, Jodrell Bank’s colossal moveable dish is still one of the world’s most powerful radio telescopes
Nearly 60 years ago this month, The Engineer was invited by the Department of Scientific and Industrial Research to visit the Jodrell Bank Observatory in Cheshire. The purpose of the visit was to get a behind-the-scenes look at the station’s latest addition: a steerable dish radio telescope that at the time was the largest in the world.
Known today as the Lovell Telescope – in honour of its chief proponent, the late Sir Bernard Lovell (who gave one of his final interviews to The Engineer)– the construction garnered attention for several reasons. “This enormous instrument is of special interest, not only for the uniqueness and promise for the astronomer but also because of the engineering problems that had to be surmounted to design and build it,” wrote The Engineer in 1957. “Civil, mechanical and electrical engineering techniques are all involved in the successful operation of the radio telescope, sometimes in an original manner.”
With a moveable dish 76.2m (250ft) in diameter, the Lovell telescope is today still the third-largest telescope of its type, as well as a Grade I-listed building. In 2006 it won a BBC competition as the UK’s greatest ‘Unsung Landmark’. But what are now its storied history and place in the national consciousness were, of course, unknown to our predecessors all those years ago, whose focus was primarily the telescope’s construction and operation.
The article went into detail: “The bowl…is carried on two towers by trunnion bearings; it can be turned on those bearings through 180 deg. The towers are mounted on bogies on a circular rail track so that the whole structure can be rotated. Driving and control mechanisms are installed in such a manner that the telescope can be pointed at any given star and can be driven to follow the path of the chosen star till it disappears below the horizon.”
Despite aluminium alloy initially being offered as a possible construction material, the consultants ultimately chose to build the entire telescope from steel. Steel provided the highest strength/cost ratio and had a low coefficient of expansion, meaning that reasonable accuracy of the dish’s shape could be maintained. It was also judged the best material to help overcome one of the telescope’s key challenges: the wind.
Stability in wind was a key consideration and the telescope had to be steady enough to maintain the bowl’s accuracy in moderate winds of 30–40mph. The first designs of the telescope “allowed deflections of several inches – say 6in or 7in”. However, the iteration that was ultimately built meant that “any deviation of the skin of the paraboloid from its true shape [was] intended to be kept down to about 1in”.
The bowl itself was constructed from more than 7,000 stiffened steel plates of 3ft by 3ft, welded to purlins. The purlins were bolted together and attached to the main structure of the telescope, enabling alignment of the shape of the bowl by adjusting the bolted connections. According to this magazine, detailing of the steelwork was “unusually onerous” due to both the structure’s unusual shape and the high degree of accuracy required.
“An idea of the complexity of this aspect of the work may perhaps be given by referring to the purlins. There are 2,200 angle-iron purlins carrying the surface of the bowl. Each had to be curved to different diameters in two planes, so that a purlin lay truly on the surface with one side of the angle iron parallel to it.”
If necessary, the bowl could be fully inverted, with the intention that the telescope could be placed in this position whenever the 62.5ft aerial mast needed to be changed. As for the bowl’s surface, a synthetic flat white paint was specified in order to “prevent a serious concentration of heat”, as well as “encourage a high degree of diffuse reflection of the sun’s rays, so that the steel membrane itself does not get too hot”.
Of course, much work has been done in the intervening 59 years to maintain and upgrade the telescope. Since 2010, the dish has been protected from pigeons’ and other birds’ foulings by two breeding pairs of peregrine falcons (one in each of the telescope’s two support towers). An indication of the structure’s endurance, however, is the fact that, since 1957, just two of the original 64 drive wheels that help it track stars across the night sky have needed to be replaced. They certainly don’t build ’em like they used to.
Great to read about this: and I did re-read my 2014 comments!
When I first came back to the UK (my country) in 1970/71 from the USA I joined a textile machinery firm in the N West. Before renting a house, I stayed for a month or so in a small commercial hotel. One of my fellow guests was an Engineer from British Steel (indeed it might have been called something else then!) who was the ‘site’ engineer and one of the designers for the refurbishment of the telescope: particularly the addition of the second support cradle on which the enhanced (more accurate) bowl was now to be supported.
The two pictures in the article show this before and after modification well.
At breakfast and supper each day for some weeks I was treated to a blow-by-blow account of the trials and tribulations of the project. Absolutely fascinating effort(s) not made any easier by the fact that there were many (including Sir Bernard) who had very definite ideas as to what should be done, to what time scale, in what order and by whom: cost was also a factor?
As a student, I shared an apartment with civil engineers. It was seeing them coming home, wet, muddy, tired, wind-blown which convinced me that my future lay indoors with Mechanical Engineering. Hearing of the manifest problems of rebuilding the telescope in winter, problems with sub-contractors suppliers, load bearing soil, delivery of parts, labour relations, accountants interfering confirmed that I had made the right choice!
For 33 years I have had an interest in the company, Robey of Lincoln. I founded ‘The Robey Trust’ in Tavistock in 1986 and we have a collection of over 30 engines, mainly steam, built by Robey & Co. As general structural engineers it is rumoured that it was Robeys who built the structural elements of Jodrel Bank, a suggestion I have never been able to confirm. The story extends to the notion that they used railway-wagon wheels to rotate the telescope on the circular track. Can anyone, please, confirm or refute any of this? With thanks.
You may be interested to learn, then, that we still operate a Robey of Lincoln steam raising boiler in Preston, Lancs to heat some press platens. It is denoted “Lincoln 2” and has a plate bearing “No1”
It may not be well known that the two trunnions (is that one or two ‘n’s?) that support the bowl were formerly the mountings for the turret(s) from a WWII battleship. the ultimate plough-shares into swords? [or is it the other way round?] I gather these weighed several hundred tons each: and getting them 150ft into the sky was a major headache, happily solved. Though I suspect quite a lot of asprin was involved.
Dave – Many years ago (probably about 35) I was told by a member of the Fairey aviation family who had been involved with the construction, maintenance or refurbishment of Jodrell Bank that the telescope rotated on ex-GWR Castle Class bogies. Don’t know whether that is still the case but wouldn’t doubt that it was true when I was told.
Bernie – thankyou very much for your reply. GWR Castle Class bogies are more ‘up-market’ than railway wagon wheels, but the interesting thing is that the railway ‘connection’ is there. Fascinating!
At the age of 11 in 1964 I was taken to Jodrell Bank by my uncle who lived in Liverpool with whom my parents (and thus I were staying) He thought it would be of interest to me and so it was, in fact like many at the time I had heard of it even seen pictures but as an 11 year old it blew me away. Even now I can remember some of the facts and figures 53 years later. It does represent a time when we did things on speculative basis for what it might achieve, the brainchild of men like Lovell and his contemporaries and it is in contrast to now where we have to see the payback, the benefit before funding will hit the table. This is true on so many levels and is not restricted to UK. there are exceptions still and happily LHC at CERN would appear to be one example. The bean counters have a controlling voice on the ‘shall we shan’t we?’ debate before a potential project almost before it has left the fertile minds from whence these things come. Roll on those 53 years and having been back on several occasions it still knocks my socks off and even more as this radio telescope has achieved so much more than was ever envisaged during it’s pre birth and we have to have the foresight and courage to do such things as a nation and as a world community for the greater good of science and those things that may spring from that nest of ideas.
The steam engine was developed to pump water from mines as we all know, look at all that this became to the whole world and steam (turbine) is still at the heart of every oil, nuclear, gas and coal power station on the planet. Yes, of course we would have found a different way to pull trains and yes perhaps the steam turbine would have come into being, but I doubt that somehow as the whole steam story is an evolutionary one born out of the need to rid mines in Cornwall of water.
So the question is that if Trevethick & his contemporaries had dismissed the early steam driven pumps as uneconomical and inefficient (which they were) and had abandoned the idea on those grounds what perhaps would the world look like between then and now? The first integrated circuits did not reveal just how far that would take us, again what would we be doing now without the powerful ARM chips and others. The sheer power of a single smart phone is just staggering and would have had all but the most foresighted boffins 60 – 70 years ago just gaping in disbelief.
Speculative work in science has repeatedly proven to have borne some of the greatest chains of evolution of the last 200 years. Faraday is ‘reputedly’ to have said upon discovering the effects of induced current in a wire. ‘This is exciting but I know not how it might benefit mankind’
Your closing comment “They certainly don’t build ’em like they used to” may well be true. In the case of the main trunnion bearings, they were supplied by Cooper Bearings in Norfolk. These bearings were designed specifically for the telescope, they have never been replaced and are still going strong, I know this because I am a designer at Cooper Bearings and I believe we do actually build ’em like they used to!
“steam engine was developed to pump water from mines as we all know, look at all that this became to the whole world ” S Eren Dipidity is perhaps the most respected and valuable researcher in the world! Taking an existing technology and applying it to a new problem.
[Isn’t that what those trained and educated in STEM do all the time?] Many of the earliest drugs and medicines came from the research into new dyestuffs for brighter colours in textiles.
Though my caveat is that perhaps a percentage (decided by science, not finance and politics) of R&D should concentrate on the D -development. I believe this is where Engineering (science application) is at a disadvantage: there is little academic kudos in such, and its still a step or two away from generating profits, so it does not occur as much or often as it should.
Re wheelsets : Castle class bogie wheels ( possibly originating from the earlier Star class , some of which were rebuilt into Castle class ) were considered for use in the new-build Saint class loco , Lady of Legend . However ultrasonic testing revealed the wheels had hairline cracks in alternate spokes , so deemed unsuitable for Didcot’s new-build loco , q.v.. ( Star class wheels from under a Radio Telescope ! )
very interesting information, specially the protection of disc from corrosion and maintaining its smoothness so long working at the age of 62.