Comment »Posted on Monday 20 April 2009 at 11:42 am by Colin Stuart
In Space & Astronomy

One of the most powerful telescopes ever constructed has finally seen first light. The e-MERLIN array, centred on The Jodrell Bank Observatory in Cheshire, is the only system of telescopes in the world capable of rivalling the Hubble Space Telescope (HST) for resolution.

In order to achieve this one telescope is not sufficient. Instead e-MERLIN is made up of seven radio telescopes separated by 217km and spread all over Britain. It turns out that the maths behind this is very simple. To work out the resolution of your telescope all you have to do is divide the wavelength of the signal you are receiving by the diameter of your telescope. That’s it. So the e-MERLIN is almost three thousand times more sensitive than the Lovell Telescope at Jodrell, itself a leviathan in ‘scope terms, at 76m. It is the Lovell (which you can see me climbing in a short film about it, here) which is the centre-piece of the array and makes up a considerable fraction of the observing power.

A map showing the 7 e-MERLIN telescope spread across the country.

However, this system of telescopes is not new; it is used to be called MERLIN. What makes e-MERLIN new is the way that the seven telescopes communicate with one another. Super-fast optical fibres have now been laid underground to replace the old system of microwave transmission which restricted astronomers to receiving only 1% of the signal received at the telescopes. Dr Tim O’Brien, Head of Public Outreach at Jodrell, is likening the upgrade to switching from dial-up to broadband internet. In truth, this is an understatement. The upgrade means that that e-MERLIN can now do in one day what used to take three years to achieve.

This speedy connection and almost unrivalled resolution means that the array can tackle new astronomy when it goes fully online at the beginning of next year. Jodrell’s speciality is pulsars, rapidly rotating neutron stars formed when massive stars collapse at the end of their lifetimes. These exotic objects are so dense that just a spoonful of their material would weigh more than every person on Earth put together. Over 100 institutions worldwide have bid for observing slots on e-MERLIN, to study pulsars and other cosmic phenomenon that stretch all the way out to the edge of the observable universe.

But it almost didn’t happen. In a spending review in early 2008, the UK funding panel the STFC decided to pull the plug on the funding for Jodrell and the e-MERLIN upgrade. At the time I was a final year undergraduate at The University of Manchester, the university which owns and operates Jodrell and e-MERLIN. The department rallied together to try and save what we felt was a very necessary project from losing funding. For my part I shot and directed a campaign video airing the views of the students and explaining what actions could be taken to save the project. I also went on local TV to argue the case for overturning the decision. Eventually, at the eleventh hour, the STFC had a change of heart and the project was saved.

So as an ex-Jodrellite and for my former colleagues who campaigned for this cutting edge project to continue, today is a very proud day.


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