Monster telescope gets the go-ahead

The go-ahead has been given to build the world’s largest optical telescope, a monster European eye on the sky in Chile. Member states of the European Southern Observatory (ESO) agreed to start work on the £875 million European Extremely Large Telescope (E-ELT) at a meeting of its governing Council in Garching, Germany.

Impression of the E-ELT above the clouds. Credit: ESO

Last year, Skymania’s Paul Sutherland visited Cerro Armazones, the mountaintop site in the dry Atacama Desert picked for this monster instrument which will have a segmented mirror 39.3 metres that can collect 12 times more light than the current biggest telescopes.

It was a white-knuckle ride getting up there as a four-wheeled off-roader raced across a rock-strewn, red desert landscape that resembled Mars to carry us to a 3,000-metre high, desolate summit that will be transformed when construction work begins.

Engineers will have to blast the top off the mountain to build the telescope which will be nearly as tall as Big Ben and cover an area the size of a stadium. But construction work will not begin until contributions pledged by the member states of ESO exceed 90 per cent of the estimated 1,083 million euro cost of the telescope. Individual ESO partners will now be pressing their governments to guarantee this funding.

Its sensitivity to visible and infrared light – tens of times greater than any present telescope – is expected to allow astronomers to peer back billions of years in time to the first galaxies to form in the early universe nearly 14 billions years ago.

It will directly image planets around nearby stars and help identify Earth-like rocky worlds that might be home to life. It could also unlock secrets of dark matter and dark energy – little understood forces in astronomy – to help explain how the universe developed.

Instruments attached to the telescope will include spectrometers to help astronomers analyse the light received from space. Others will to allow the telescope to remove blurring distortions caused by the Earth’s atmosphere, a process termed adaptive optics which will produce pictures 15 times sharper than those taken by the Hubble space telescope.

Professor Gerry Gilmore, of Cambridge University, said: “UK technology and industry will benefit enormously, and British scientists will be able to lead in the next stages of mankind’s discovery of the nature of time, matter, existence, the origin and far future of the Universe, and the expected discovery of life far outside our own Solar System. The intellectual opportunities are immense, the challenges vast, the potential almost unlimited.

Skymania’s Paul Sutherland at the E-ELT site. Image credit: Emily Baldwin

The E-ELT will be the latest major astronomical tool to join a number of observatories operated in Chile by Europe. The Atacama is a favoured location because the dryness and clarity of the air provide exceptional observing conditions.

Established telescopes there include the Very Large Telescope (VLT) at Paranal, which is actually four giant telescopes, each with a 8.2-metre wide main mirror, that can work separately or together.

Another, called ALMA, short for the Atacama Large Millimeter Array, is an array of dishes that form the highest observatory in the world at 5,000metres (16,000ft). They will observe the sky together at very short wavelengths which are invisible to the eye.

The UK’s focus on the ESO telescopes in Chile have come at a cost with the gradual withdrawal from other established observatories, notably on Hawaii, as Skymania reported last month.

Skymania was interested to note that there is already a telescope on the mountaintop at Cerro Armazones, but considerably smaller than the E-ELT will be. It was a Celestron of the type owned by many amateur astronomers and was being used to test observing conditions.

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