The Lovell Telescope ( LUV-əl) is a radio telescope at Jodrell Bank Observatory, near Goostrey, Cheshire, in the north-west of England. Completed in 1957, the telescope was the largest steerable dish radio telescope in the world at 76.2 metres (250 feet) in diameter; it is now the third-largest, after the US Green Bank telescope, and German Effelsberg telescope. Originally known as the "250 ft telescope" or the Radio Telescope at Jodrell Bank, it became the Mark I telescope from 1960 as future telescopes (the Mark II, III, and IV) began design. It was renamed the Lovell Telescope in 1987 after Sir Bernard Lovell, and became a Grade I listed building in 1988. The telescope forms part of the MERLIN and European VLBI Network arrays of radio telescopes. The telescope was influential in the early detections of extragalactic objects including quasars, astrophysical masers, and Einstein rings. Soviet and US probes of the Space Race were tracked en route to the Moon, Venus, and Mars; in 1966 it received the first imagery from the Moon's surface taken by Luna 9. At a height of the Cold War in 1962 and 1963, the telescope operated as an early-warning radar of the four-minute warning system for the Soviet Strategic Rocket Forces. Both Bernard Lovell and Charles Husband were knighted for their roles in creating the telescope. In September 2006, the telescope won the BBC's online competition to find the UK's greatest "Unsung Landmark". The telescope is visible from Manchester Airport, high-rise buildings in Manchester such as the Beetham Tower, and distant vantage points such as the Pennines, Winter Hill, Snowdonia, Beeston Castle, and the Peak District.
Construction
Conception and construction of the Mark I Bernard Lovell built the Transit Telescope at Jodrell Bank in the late 1940s. This was a 218 ft (66 m)-diameter radio telescope that could only point directly upwards; the next logical step was to build a telescope that could look at all parts of the sky so that more sources could be observed, as well as for longer integration times. Although the Transit Telescope had been designed and constructed by the astronomers that used it, a fully steerable telescope would need to be professionally designed and constructed; the first challenge was to find an engineer willing to do the job. This turned out to be Charles Husband, whom Lovell first met on 8 September 1949.
Two circular 15" turret drive gear sets and associated pinions from 15-inch (38-cm) gun turrets were bought cheaply in 1950; these came from the World War I battleships HMS Revenge and Royal Sovereign, which were being broken up at the time. The bearings became the two main altitude rotator bearings of the telescope, with the appropriate parts of the telescope being designed around them. Husband presented the first drawings of the proposed giant, fully steerable radio telescope in 1950. After refinements, these plans were detailed in a "Blue Book", which was presented to the DSIR on 20 March 1951; the proposal was approved in March 1952. Construction began on 3 September 1952. The foundations for the telescope were completed on 21 May 1953 after being sunk 90 ft (27 m) into the ground. It then took until mid-March 1954 to get the double railway lines completed because of their required accuracy. The central pivot was delivered to the site on 11 May 1954, and the final bogie in mid-April 1955.
The telescope bowl was originally going to have a wire mesh surface to observe at wavelengths between 1 and 10 meters (3.3 and 32.8 ft), so frequencies between 30 and 300 MHz; this was changed to a steel surface so that the telescope could observe at the 21 cm (8.3 in) hydrogen line, which was discovered in 1951. Also, in February 1954 Lovell and the Air Ministry met to see if funding could be made available for improving the accuracy of the dish so that it could be used on centimetre wavelengths, for research at these wavelengths for the Ministry as well as "other purposes". Although the funding was not ultimately made available from the Air Ministry, the planning process had already progressed, so this improvement was made anyway. The telescope was constructed so that the bowl could be completely inverted. Originally, it was intended to use a movable tower at the base of the telescope to change the receivers at the focus. However, the movable tower was never built, jointly because of funding constraints and the fact that much of the receiver equipment was placed at the base of the telescope rather than at the focus. Instead, receivers were mounted on 50-foot (15-m) long steel tubes, which were then inserted by a winch into the top of the aerial tower while the bowl was inverted. The cables from the receivers then ran down the inside of this tube, which could then be connected when the telescope was pointed at the zenith. Associated receiver equipment could then be placed either in the small, swinging laboratory directly underneath the surface; in rooms at the tops of the two towers; at the base girders, or in the control building. The telescope moved for the first time on 3 February 1957: by an inch. It was first moved azimuthally under power on 12 June 1957; the bowl was tilted under power for the first time on 20 June 1957. By the end of July the dish surface was completed, and first light was on 2 August 1957; the telescope did a drift scan across the Milky Way at 160 MHz, with the bowl at the zenith. The telescope was first controlled from the control room on 9 October 1957, by a purpose-built analogue computer. There were large cost overruns with the telescope's construction, mainly the result of the steeply rising cost of steel during construction. The original grant for the telescope came jointly from the Nuffield Foundation and the government; this amounted to £335,000. The government increased its share of the funding several times as the cost of the telescope rose; other money came from private donations. The final part of the debt from the construction of the telescope, £50,000, was paid off by Lord Nuffield and the Nuffield Foundation on 25 May 1960 (partly because of the telescope's early, very public role in space probe tracking; see below), and Jodrell Bank observatory was renamed to the Nuffield Radio Astronomy Laboratories. The final total cost for the telescope was £700,000.
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