Jodrell Bank Observatory

Jodrell Bank Observatory
The 76 m Lovell Telescope at Jodrell Bank Observatory
Organization	University of Manchester
Location	Lower Withington, Cheshire, England
Established	1945
Website www.jb.man.ac.uk
Telescopes Lovell Telescope prime focus Mark II prime focus

The Jodrell Bank Observatory (originally the Jodrell Bank Experimental Station, then the Nuffield Radio Astronomy Laboratories from 1966 to 1999) is an observatory that hosts a number of radio telescopes, and is part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Sir Bernard Lovell, who wanted to investigate cosmic rays after his work on radar during the Second World War. It has since played an important role in the research of meteors, quasars, pulsars, masers and gravitational lenses, and was heavily involved with the tracking of space probes at the start of the Space Age.

The main telescope at the observatory is the Lovell Telescope, which is the third largest steerable radio telescope in the world. There are three other active telescopes located at the observatory; the Mark II, as well as 42 ft (13 m) and 7 m diameter radio telescopes. Jodrell Bank Observatory is also the base of the Multi-Element Radio Linked Interferometer Network (MERLIN), a National Facility run by the University of Manchester on behalf of the Science and Technology Facilities Council.

In March 2008, the future of Jodrell Bank was placed in doubt after the threat of withdrawal of government funding for the observatory's key e-MERLIN project. In July 2008, however, a three-year funding deal was agreed, allowing work on the project to continue.^[1]

The site of the observatory, which includes the Jodrell Bank Arboretum, is located in the civil parish of Lower Withington (the rest being in Goostrey civil parish), near Goostrey and Holmes Chapel in Cheshire East, North West England.

Early years

Observations at Jodrell Bank in 1945

Jodrell Bank was first used for academic purposes in 1939 when the University of Manchester's horticultural botany department purchased three fields at the site. The name of the site came from a nearby ground rise called Jodrell Bank, which was named after the descendants of William Jauderell who lived in a mansion that is now Terra Nova School. The site was extended in 1952 by the purchase of a farm from a local farmer, George Massey. The new land included the site upon which the Lovell Telescope was sited.^[2]

The first use of the site for astrophysics was in 1945, when Bernard Lovell wished to use some equipment left over from World War II, including a gun laying radar to investigate cosmic rays.^[3] The equipment he was using was a GL II radar system working at a wavelength of 4.2 m, provided by J. S. Hey.^[4][5] He originally intended to use the equipment in Manchester, however electrical interference from the trams that then ran down Oxford Road prevented him from doing so. Consequently, he moved the equipment to Jodrell Bank, 25 miles (40 km) south of the city on 10 December 1945.^[5][6] Lovell's main topic of research at the time were transient radio echoes, which he confirmed were from ionized meteor trails by October 1946.^[7] Coincidentally, the first time he turned the radar on at Jodrell Bank — the 14 December 1945 — the Geminids meteor shower was at a maximum.^[6]

Over the next few years, he accumulated more ex-military radio hardware, including a portable cabin, commonly known as a "Park Royal" in the military. The first permanent building on the site was located near to this cabin, and was named after it.^[7]

Searchlight telescope

A searchlight was loaned to Jodrell Bank in 1946 by the Army;^[8] a broadside array was constructed on the mount of this searchlight by J. Clegg,^[8] consisting of a number of Yagi antennas.^[9] This was first used for astronomical observations in October 1946.^[10]

On 9 and 10 October 1946, the telescope was used to observe the ionisation in the atmosphere caused by meteors in the Giacobinids meteor shower. When the antenna was turned by 90 degrees at the maximum of the shower, the number of detections dropped to the background level, proving that the transient signals detected by radar were indeed from meteors.^[9] Shortly after this, the telescope was used to determine the radiant points for meteors. This was possible as the echo rate is at a minimum at the radiant point, and a maximum at 90 degrees to it.^[8] The telescope, as well as other receivers on the site, was also used to study auroral streamers that were visible at the site in early August 1947.^[11][12]

Transit Telescope

The Transit Telescope was a 218 ft (66 m) parabolic reflecting aerial built at Jodrell Bank in 1947. At the time, it was the largest radio telescope in the world. It consisted of a wire mesh suspended from a ring of 24 ft (7.3 m) scaffold poles, which focussed radio signals to a focal point 126 ft (38 m) above the ground. The telescope mainly looked directly upwards, but the direction of the beam could be changed by small amounts by tilting the mast to change the position of the focal point. The focal mast was originally going to be wood, but this was changed to a steel mast before construction was complete.^[2] The telescope was replaced by the fully-steerable, 250 ft (76 m) Lovell Telescope, and the Mark II telescope was subsequently built on the same location.

The telescope was able to map a ± 15 degree strip around the zenith at 72 and 160 MHz, with a resolution at 160 MHz of 1 degree.^[13] It was used to discover radio noise from the Great Nebula in Andromeda—the first definite detection of an extragalactic radio source—and the remains of Tycho's Supernova in the radio frequency; at the time it had not been discovered by optical astronomy.^[14]

Lovell Telescope

The Lovell Telescope

The "Mark I" telescope, now known as the Lovell Telescope, was the largest steerable dish radio telescope in the world, 76.2 m (250 ft) in diameter, when it was completed in 1957;^[15] it is now the third largest, after the Green Bank and Effelsberg telescopes.^[16] Part of the gun turret mechanisms from the battleships HMS Revenge and Royal Sovereign were reused in the motor system for the telescope.^[17] The telescope became operational in the summer of 1957, just in time for the launch of Sputnik 1, the world's first artificial satellite. The telescope was the only one in the world able to track Sputnik's booster rocket by radar;^[18] it first located it just before midnight on 12 October 1957.^[19][20]

In the following years, the telescope was used to track a variety of space probes. Between 11 March and 12 June 1960, it tracked the Pioneer 5 probe. The telescope was also used to send commands to the probe, including the one to separate the probe from its carrier rocket and the ones to turn on the more powerful transmitter when the probe was eight million miles away. It also received data from the probe, being the only telescope in the world capable of doing so at the time.^[21] In February 1966, Jodrell Bank tracked the USSR unmanned moon lander Luna 9 and listened in on its facsimile transmission of photographs from the moon's surface. The photos were sent to the British press and published before the Soviets themselves had made the photos public.^[22]

In 1969 the Soviet Union's Luna 15 was also tracked. Luna 15 was a last minute Soviet attempt to steal some of Apollo 11's publicity. A recording of the dramatic moment in which Jodrell Bank's scientists observed a Soviet attempt to scupper American victory in the race to the Moon was made available to the public for the first time on 3 July 2009.^[23]

Despite the publicity surrounding the telescope's tracking of space probes, this only took up a fraction of its observing time, with the remainder used for scientific observations. These include using radar to measure the distance to the Moon and to Venus;^[24][25] observations of astrophysical masers around star-forming regions and giant stars;^[26] observations of pulsars (including the discovery of millisecond pulsars^[27] and the first pulsar in a globular cluster);^[28] observations of quasars and gravitational lenses (including the detection of the first gravitational lens^[29] and the first einstein ring).^[30] The telescope has also been used for SETI observations.^[31]

Mark II and III telescopes

The Mark II

The Mark II is an elliptical radio telescope, with a major axis 125 ft (38.1 m) and a minor axis of 83 ft 4 in (25.4 m).^[32] It was constructed in 1964. Aside from operating as a standalone telescope, it has also been used as an interferometer with the Lovell Telescope, and is now primarily used as part of MERLIN (see below).^[33][34]

The Mark III telescope was the same size as the Mark II, but was constructed to be transportable.^[35] However, it was never moved, and remained at its original site in Wardle, near Nantwich, where it was used as part of MERLIN. It was built in 1966, and was decommissioned in 1996.^[36]

Mark IV, V and VA telescopes

A model of the proposed Mark V radio telescope

The Mark IV, V and VA telescopes were three proposals that were put forward in the 1960s through to the 1980s to build an even larger radio telescope than the Lovell. The Mark IV would have been a 1,000 ft (305 m) diameter standalone telescope, built as a national project. The Mark V would have been a 400 ft (122 m) moveable telescope. The original concept of this telescope had it located on a 3/4 mile long railway line adjoining Jodrell Bank, however concerns about the future levels of interference meant that a site in Wales would have been used (the preferred site was near Meifod). Several design proposals were put forward, one by Husband and Co., the other by Freeman Fox, who had designed the Parkes Observatory telescope. The Mark VA followed on from the Mark V, but with a smaller dish of 375 ft (114 m) and a design using prestressed concrete, similar to the Mark II (the previous two designs more closely resembled the Lovell telescope).^[37]

None of the three telescopes were constructed, although several design studies were carried out and some scale models were made. This was due partly due to the political climate at the time (including the transition from a Labour Party government under Harold Wilson to a Conservative Party one under Margaret Thatcher), and partly to the financial constraints of astronomical research in the UK at the time. Also, at a vital time, it became necessary to upgrade the Lovell Telescope to the Mark IA, which subsequently overran in terms of cost.^[37]

Other single dishes

Undergraduate teaching telescope, with the Lovell telescope in the background

A 50 ft (15 m) alt-azimuth dish was also in use on the site; this was built in 1964. In addition to astronomical research, it was used to track the Zond 1, Zond 2, Ranger 6 and Ranger 7 space probes,^[38] and also Apollo 11.^[39] The 50 ft telescope was demolished in 1982, when it was replaced with a more accurate telescope named the "42ft" following an accident that irreparably damaged the 50 ft telescope's surface. The 42 ft (12.8 m) dish is mainly used for observations of pulsars, and is normally continually monitoring the Crab Pulsar.^[40]

At the same time as the 42 ft was installed, a smaller dish called the "7 m" (actually 6.4 m, or 21 ft, in diameter) was installed and is now used for undergraduate teaching. Both the 42 ft and 7 m telescopes were originally used at the Woomera Rocket Testing Range in Australia.^[41] The 7 m was originally constructed in 1970 by Marconi Company.^[42]

A Polar Axis telescope was built at Jodrell Bank in 1962. This had a circular 50 ft (15.2 m) dish on a polar mount,^[43] and was mostly used for moon radar experiments. It has since been decommissioned. There has also been an optical telescope at the observatory; an 18-inch (460 mm) reflecting optical telescope was donated to the observatory in 1951.^[44] However, this telescope was not used much, and was in turn donated to the Salford Astronomical Society around 1971.^[45]

MERLIN

The Multi-Element Radio Linked Interferometer Network (MERLIN) is an array of radio telescopes spread across England and the Welsh borders. The array is run from Jodrell Bank on behalf of the Science and Technology Facilities Council as a National Facility.^[46] The array consists of up to seven radio telescopes and includes the Lovell Telescope, Mark II, Cambridge, Defford, Knockin, Darnhall and Pickmere (previously known as Tabley). The longest baseline is therefore 135 mi (217 km) and MERLIN can operate at frequencies between 151 MHz and 24 GHz.^[36] At a wavelength of 6 cm (5 GHz frequency), MERLIN has a resolution of 50 milliarcseconds which is comparable to that of the HST at optical wavelengths.^[46]

Very Long Baseline Interferometry

Jodrell Bank has been involved with Very Long Baseline Interferometry (VLBI) since the late 1960s; the Lovell telescope took part in the first transatlantic interferometer experiment in 1968, with other telescopes being those at Algonquin and Penticton in Canada.^[47] The Lovell Telescope and the Mark II telescopes are regularly used for VLBI with telescopes across Europe (the European VLBI Network), giving a resolution of around 0.001 arcseconds.^[33]

Research

The Jodrell Bank Centre for Astrophysics, of which the Observatory is a part, is one of the largest astrophysics research groups in the UK.^[48] Naturally, the main focus of the group is radio astronomy—including research into pulsars, the Cosmic Microwave Background Radiation, gravitational lenses, active galaxies and astrophysical masers. The group also carries out research at different wavelengths, looking into star formation and evolution, planetary nebulae and astrochemistry.^[49]

The first director of Jodrell Bank was Bernard Lovell, who established the observatory in 1945. He was succeeded in 1980 by Sir Francis Graham-Smith, followed by Professor Rod Davies around 1990 and Professor Andrew Lyne in 1999.^[50] The current director is Professor Phil Diamond, who took over the role on 1 October 2006.

There is also an active development programme researching and constructing telescope receivers and instrumentation. The observatory has been involved in the construction of several Cosmic Microwave Background experiments, including the Tenerife Experiment, which ran from the 1980s to 2000, and the amplifiers and cryostats for the Very Small Array.^[51] It has also constructed the front-end modules of the 30 and 44 GHz receivers for the Planck spacecraft.^[52] Receivers were also designed at Jodrell Bank for the Parkes Telescope in Australia.^[53]

Visitor facilities

A view of the telescope from the Arboretum

There is an educational visitors' centre at the site, which covers the history of Jodrell Bank and also has a 3D theatre hosting trips to Mars.^[54] There is also a path around the Lovell telescope, approximately 20 m from the telescope's outer railway, which hosts a number of information boards explaining how the telescope works and the research that is done with it. The visitor's centre also organizes a series of public outreach events, including public lectures, star parties and "ask an astronomer" sessions.^[55] There is also an astronomy podcast from the observatory, named The Jodcast.^[56]

The original visitors centre, opened on 19 April 1971 by the Duke of Devonshire,^[57] attracted around 120,000 visitors per year. Due to concerns of the safety of the buildings, the visitor's centre was mostly demolished in 2003 with a new science centre being planned at the time. However, the plans were shelved when Manchester University and UMIST merged to become the University of Manchester in 2004. New proposals are currently (August 2008) being developed, to be revealed by the end of 2008.^[58] An interim centre exists, which currently receives around 70,000 visitors a year.^[59]

The 35 acre (140,000 m²) Jodrell Bank Arboretum, created in 1972, houses the UK's national collections of crab apple Malus and mountain ash Sorbus species, as well as the Heather Society's Calluna collection. The arboretum also features a small scale model of the solar system, the scale being approximately 1:5,000,000,000. As part of the SpacedOut project, Jodrell Bank is also the location of the Sun in a 1:15,000,000 scale model of the solar system covering the UK.^[60]

Threat of closure

On 3 March 2008 it was reported that Britain's Science and Technology Facilities Council (STFC), faced with an £80 million shortfall in its budget, was considering withdrawing its planned £2.7 million annual funding of Jodrell Bank's e-MERLIN project. The project, which aims to replace the microwave links between Jodrell Bank and a number of other radio telescopes with high-bandwidth fibre-optic cables, greatly increasing the sensitivity of observations, is seen as critical to the survival of the establishment in its present form. Sir Bernard Lovell was quoted as saying "It will be a disaster … The fate of the Jodrell Bank telescope is bound up with the fate of e-MERLIN. I don't think the establishment can survive if the e-MERLIN funding is cut."^[61][62]

On Monday 14 April 2008, Cheshire's 106.9 Silk FM unveiled to its listeners their own campaign song to save Jodrell Bank, entitled "The Jodrell Bank Song" and sung by a group dubbed "The Astronomers". Along with the song, the Silk FM team also produced a music video filmed in front of the iconic Lovell telescope. Silk FM released the song for download from Monday 21 April 2008. All proceeds went towards saving Jodrell Bank. On 9 July 2008, it was reported that, following an independent review, the STFC had reversed its initial position and would after all guarantee funding of £2.5m annually for three years.^[1]

Fictional references

Jodrell Bank has been mentioned in several popular works of fiction, including Doctor Who (Remembrance of the Daleks, The Poison Sky and most notably Logopolis), The Hitchhiker's Guide to the Galaxy^[63] (as well as The Hitchhiker's Guide to the Galaxy film), The Creeping Terror and Meteor.

References

Books

• Adams, Douglas (1986). Hitchhiker's Guide to the Galaxy—A Trilogy in Four Parts. Pan Books. ISBN 0-330-31611-7. 
• Gunn, A. G. (2005). "Jodrell Bank and the Meteor Velocity Controversy". In The New Astronomy: Opening the Electromagnetic Window and Expanding Our View of Planet Earth, Volume 334 of the Astrophysics and Space Science Library. Part 3, pages 107–118. Springer Netherlands. doi:10.1007/1-4020-3724-4_7
• Lovell, Bernard (1968). Story of Jodrell Bank. Oxford University Press. ISBN 0-19-217619-6 (hardback). 
• Lovell, Bernard (1973). Out of the Zenith: Jodrell Bank, 1957–70. Oxford University Press. ISBN 0-19-217624-2 (hardback). 
• Lovell, Bernard (1985). The Jodrell Bank Telescopes. Oxford University Press. ISBN 0-19-858178-5 (hardback). 
• Lovell, Bernard (1990). Astronomer by Chance. London: Macmillan. ISBN 0-333-55195-8. 
• Piper, Roger (1972) [1965]. The Story of Jodrell Bank (Carousel ed.). London: Carousel. ISBN 0-552-54028-5. 
• Pullan, Brian; Abendstern, Michele (2000). A history of the University of Manchester 1951–1973. Manchester University Press. ISBN 0-7190-5670-5. 

Journal articles

• Palmer, H. P.; B. Rowson (1968). "The Jodrell Bank Mark III Radio Telescope". Nature 217: 21–22. doi:10.1038/217021a0. 

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