Jodrell Bank Observatory

From radar to radio astronomy

Bernard Lovell, a physicist who had worked on airborne radar in the war, moved to the University of Manchester's botanical station at Jodrell Bank in 1945, away from the electrical interference of the city, to study cosmic-ray showers with surplus radar equipment. He found that the radar echoes of meteors could be detected in daytime, and soon moved from radar to the radio waves that stars and galaxies emit.

He wanted a much larger steerable dish. Construction of the Mark I telescope began in 1952, with a 76-metre bowl on a pair of towers, and it was completed in 1957. It cost far more than planned, and the funding was rescued in 1960 by a grant from the Nuffield Foundation.

Sputnik and after

In October 1957, weeks after the telescope was finished, the Soviet Union launched Sputnik 1. The Mark I was the only instrument in the world that could track the rocket's carrier stage by radar, and it did. The dish tracked the Pioneer and Luna probes in the following years and became a symbol of British science.

Its pulsar group, led by Andrew Lyne and Francis Graham-Smith, has monitored the Crab pulsar since 1968, one of the longest continuous pulsar records. The telescope was renamed the Lovell Telescope in 1987, and was resurfaced and upgraded in the 1970s and again around 2002.

A world heritage observatory

Jodrell Bank is the hub of the e-MERLIN array of seven radio telescopes spread across England, and the headquarters of the Square Kilometre Array Observatory, the global radio telescope under construction in Australia and South Africa. UNESCO inscribed Jodrell Bank Observatory on the World Heritage List in 2019, citing its role in the development of radio astronomy. The University of Manchester runs the observatory, with a visitor centre.

A telescope that nearly was not built

The Mark I telescope cost many times its first estimate and nearly bankrupted the university, and the funding was rescued only when the telescope proved its value in October 1957. That early history shaped the way British science is funded: large facilities are justified by the case that they will do things no other instrument can do, and are judged by their results. Jodrell Bank's later work in pulsar timing and in very long baseline interferometry grew from that capability, and the observatory's long record of Crab pulsar timing is a product of the stability that the large dish gave.

Instruments and technologies

• Lovell Telescope A 76-metre fully steerable parabolic dish on an alt-azimuth mount, weighing about 3,200 tonnes, with the bowl suspended between two towers.
• e-MERLIN array Seven telescopes linked by fibre across England, with baselines up to 217 km, combined as an interferometer.
• Pulsar timing receivers Digital back ends that fold the pulses of a pulsar and compare their arrival times to an atomic clock.

The people

• Bernard Lovell Founder and director; built the Mark I telescope.

Timeline

• 1945 Bernard Lovell begins work at the site.
• 1952 Construction of the Mark I telescope begins.
• 1957 Telescope completed; it tracks Sputnik's booster rocket in October.
• 1987 The Mark I is renamed the Lovell Telescope.
• 2019 Inscribed on the UNESCO World Heritage List.

Key lessons for observation today

• Locate away from interference Lovell moved out of Manchester because of electrical noise. Radio observatories, like magnetic ones, depend on a quiet environment.
• Open instruments find unplanned uses A telescope built for astronomy tracked a rocket. General-purpose infrastructure will be used for what no one planned.
• Keep a long monitoring series The Crab pulsar record spans more than fifty years. A monitoring programme that never stops is worth more than any single result.

Sources

• Wikipedia, Jodrell Bank Observatory
• Jodrell Bank, The Story of Jodrell Bank
• Wikipedia, Bernard Lovell
• UNESCO World Heritage Centre, Jodrell Bank Observatory