Building record 7756/3 - Jodrell Bank Observatory: 42ft Foot Telescope

<1> Historic England, 2015-, Notification Report of Decision not to Designate, Fox P, 11/07/2017 (Written Communication). SCH7825.

'...History
The observatory at Jodrell Bank is one of the earliest planned sites for radio-telescopes in the world. As such it had a pivotal role in the development of the new science of radio astronomy which was one of the first steps towards modern Astrophysics, revolutionising our understanding of the Universe. The site was first used for academic purposes in 1939 when the University of Manchester's Botany Department purchased three fields in the Cheshire countryside covering around 11 acres. The earliest use of the site for radio astronomy occurred in December 1945 when Bernard Lovell, who worked for the university’s Physics Department, moved here to escape the radio interference that occurred in Manchester city centre. His first observations used ex-army radar equipment located at the south end of the site, close to two pre-existing botany huts. Subsequently his team expanded northwards with the continuing construction of more permanent buildings, and purpose-built aerials and telescopes to support their research. Jodrell Bank’s status as a world-class centre of ongoing scientific research continues to this day with the construction of the global headquarters for the Square Kilometre Array project linking hundreds of telescopes and aerials in South Africa and Western Australia.

In 1964 a 50ft-diameter telescope was installed close to the Control Building, on a podium building of concrete. Soon afterwards, a single-storey eastward extension of the south wing of the Control Building was built abutting this podium building. Ordnance Survey (OS) maps of 1969-74 depict the building as square in plan. However, it is known that OS maps are factually incorrect in their depictions of other parts of the site at this period, and it is possible that the survey took place before construction was complete. Building plans show four columns on a square pattern, corresponding with the position of large square columns now visible within the building and engaged with the walls. However, the current enclosed form of the building seems to predate its attachment to the Control Building in the late 1960s, and the likelihood is that this was the original configuration.

In 1982, the 50ft-diameter telescope was replaced, on the same mount, by a 42ft-diameter telescope which had been donated to Jodrell Bank in 1981. The 42ft Telescope was originally built in 1974, possibly by Marconi, for the Woomera Rocket Testing Range in Australia, and became redundant when the Anglo-Australian joint defence project ceased in 1980. Since installation at Jodrell Bank, the 42ft Telescope has been mainly used for observations of pulsars, including almost-daily observations of the pulsar within the Crab Nebula.

Details
Radio telescope and podium building, 1964, telescope replaced in 1982.

MATERIALS: concrete podium and plinth, steel mount and dish.

PLAN: single-storey, rectangular building aligned east-west with the front facing east, with central pyramidal plinth for mounting the paraboloid telescope.

EXTERIOR: abutting the Control Building (not included) which stands to the west and south. The short east wall of the podium building has a central pair of timber doors set within a recess in the concrete wall. To the left, the visible portion of the S wall has two porthole windows, the rest being obscured by the attached south-east wing of the Control Building (not included in this assessment). To the right of the east wall, the north wall is visible in its entirety, with four porthole timber windows. The roof has a slight fall from the centre to the left (east). Returning to the right, the rear west wall stands close to the Control Building, and has a second doorway.

Above the podium is the plinth, a truncated tall pyramid of concrete, identical on all four sides, and surmounted by a steel platform. Above the steel platform is an octagonal gantry around the base of the steel telescope, which has four columns. Attached to two trunnion bearings at the top of the mount, the telescope comprises a paraboloid dish to the front supported by a steel lattice, with two rearward-projecting counter-weights, each with a caged access ladder running up the front face. The receiving surface has a small central hole, and a tripod-mounted receiver forward of the plane of the dish’s aperture. The exterior surfaces of the telescope and building are all painted white.

INTERIOR: the surface of the concrete structure is unpainted. Four large square-section engaged columns with widening heads support the hollow plinth. Centrally-mounted within the plinth is a cylindrical steel shaft, bolted to a square concrete pad at floor level…'

<2> Hartwell C, Hyde M, Hubbard E & Pevsner N, 2011, The Buildings of England: Cheshire (2011 revision), p.416-7 (Book). SCH7059.

<3> Chris Blandford Associates, 2016, Jodrell Bank Observatory, Conservation Management Plan (Client Report). SCH8560.

<4> Oxford Archaeology North, 2015, Jodrell Bank Control Building, Cheshire East: Historic Building Survey and Impact Assessment Report, p.55-8 (Client Report). SCH7975.

‘…[The telescope sits on a pyramidal mounting base which sits on top of] a small single storey rectangular structure, rendered in concrete…the central cell held the telescopes vertical pivot shaft which is bolted to a steel plate on the floor..’