Articles
Hawking would not have been impressed with me as a boy: I was uninterested in the TV coverage of the first men stepping on the Moon, despite my Dad’s best efforts to enthuse me.
Perhaps I would have been interested if I had visited a place like the Jodrell Bank Discovery Centre in Cheshire. Certainly when I did go there a few weeks ago, the scores of visiting schoolchildren seemed very excited about the work going on at Jodrell Bank to explore outer space. But the Jodrell Bank researchers are looking far beyond the Moon, to investigate distant galaxies, pulsars, quasars and black holes. They use the Lovell radio telescope to pick up signals that may have taken billions of years to reach us.
Two pavilions at the Discovery Centre are reserved for science shows for school groups. There are also interactive exhibits to interest children in the areas of the centre that are open to the public. Scientists from the University of Manchester do serious research at Jodrell Bank all year round, and it is remarkable that they are willing to share their space with so many noisy visitors.
The highlight of any visit is to stand alongside the Lovell telescope and to gaze up at the forest of girders that support the instrument’s enormous bulk. We’ve all seen photos of the telescope, but nothing prepares you for its sheer size. The dish measures 76m across and weighs 1,500 tonnes, and its maximum height above ground is 89m.
It was originally the biggest radio telescope in the world, and it’s still the third-largest steerable telescope. It’s been in operation throughout the Space Age. Its first act, in 1957, was to use radar to detect the rocket carrying the Soviet Union’s Sputnik I, the first artificial satellite. It was the only instrument in the world capable of this and so it became instantly famous. It went on to play a major role in astronomy.
The telescope’s dish is paraboloid, and so reflects radio waves in a way that concentrates them into a small area at the top of the central tower. Here a radio receiver converts the radio waves into electrical signals that are passed through cables to a control building, where they are digitised and stored on computer. The receiver is cooled to -260°C by the use of a vacuum, radiation shield and refrigerator. This reduces noise in the electronics and allows the detection of extremely faint radio signals. One of these receivers is on display at the entrance to the centre.
Back in the 1950s, the telescope was the brainchild of the astronomer Sir Bernard Lovell and the engineer Charles Husband. It’s refreshing to find that the key role of engineers today is given prominence in the public displays. You can tap one screen to hear members of staff talking about their work. Telescope engineer Phil Clarke says that the gears used in turning the telescope’s bowl were recycled from the gun turrets on old battleships. Part of the structure is repainted each summer. White paint is used to reduce the heat effect of the sun – thermal expansion of the dish would distort signals from space.
Another ‘talking head’, signal transport engineer Roshene McCool, describes her work in designing the Square Kilometre Array, which will become the largest radio telescope in the world. It will be a network of antennas spread over long distances in South Africa and Australia. The €1.5 billion project has its HQ at Jodrell Bank. The array will look at how the first stars and black holes were formed. McCool says it will use enough optical fibre to wrap around the world twice, and will carry data equal to 100 times the global level of internet traffic. Construction should start next year.
For more details, see: www.jodrellbank.net