Extremely Large Telescope

The European Extremely Large Telescope (E-ELT) is what it is says on the tin - and much more. Once it is built, it will be a massive piece of complex machinery, which will allow astronomers to directly view other planets for the first time.

It may take us a step closer to observing life outside of our own solar system.

"This is the story of an epic adventure," a promotional video tells us, "the story of how Europe went south to explore the stars."

It is also the story of the European Southern Observatory, an organization encompassing 15 member states and an illustrious 50 year history.

ESO has a number of state of the art telescopes based in Chile, but with the E-ELT it is about to embark on its biggest adventure yet.

"What is the E-ELT? It's the European Extremely Large Telescope, and all those words matter," says Gerry Gilmore, professor of Experimental Philosophy at the University of Cambridge. Gilmore has been involved with the E-ELT project since its inception.

A real telescope

"It's European, and it's extremely large," he says. "It's about 40 metres across the mirror and it's several times bigger than anything that has ever been built before - it's getting on for the size of a tennis court. And it's a real telescope. It's designed to take really high quality images of the night sky."

This monster telescope will be sited close to ESO's existing facilities on the edge of the high Andes - a Mecca for astronomers - on a hill called Cerro Amazonas. It is in the central northern coastal mountains of Chile, where the conditions are very clear and very dry.

"The things that mess up telescopes are water and air," says Gilmore, "they're a real nuisance if you want to look at the night sky. So you need to get as high as you can to get above the air, and dry as you can, as moisture just blurs everything out."

"It's a very beautiful place actually. You've probably seen it actually, because it was the background to one of the recent Bond movies. The observing lodge we all live in was blown up by a computer for that."

Blow the top off

But because of the sheer size of the proposed telescope, they are going to have to do some rather impressive "landscaping" to get it on top of the mountain.

"You need access for the precision instrumentation and the construction trucks and all these big pieces of machinery that can't be twisted around a corner and bumped over lumps. So the practical way to proceed is just to cut the top off the mountain. That's how we've done it for all these telescopes down in South America, so they've all turned into table-mountains. And you do that by blowing about a million tons of rock off the top," says Gilmore.

It's a lot of effort to go to for the construction of an observatory. But the plan is to use the E-ELT to answer one of life's biggest questions: are we alone?

The researchers hope to find solar systems around nearby stars.

Gilmore says there are several thousand planets known around other stars.

"Pretty soon we're going to discover a planetary system that's near to us and is lined up so we can see something that is as far from its parent sun as our Earth is from our sun. And we'll see it going round," says Gilmore.

"We'll be able to watch this planet, and we'll be able to ask 'does it go green in summer? Does it go white in winter?' And we'll be able to see it changing, and we'll be able to measure its atmosphere and say, 'do I see chlorophyll? Do I see ammonia?' We won't be able to see people waving at us, or cities or anything like that, but we'll be able to say if there's grass growing."

But the E-ELT also has uses beyond alien hunting.

At ESO's headquarters in Germany, Dr Jochen Liske says the science case for the telescope is very broad.

"It ranges across all of astronomy and astrophysics," says Liske, "so there's a lot of different things we want to be able to do with the telescope, there's no one particular question we want to answer with this machine but a whole number of different things, and it's our job to make sure the telescope can do all of those things."

With a price tag of more than a billion euros, it's no wonder the astronomers want to investigate a range of things to ensure they get value for money. It's perhaps also no wonder that some have criticized the E-ELT as being an extravagance at a time when so much of Europe is in debt.

"Out my window I can see the Allianz Arena, the home of Bayern Munich, the football club, and their annual turn over is considerably larger than ours," counters Liske. "This single - albeit very successful European football club - deals with more money than all European ground based astronomy put together. So when you put it on that scale, you realise [the cost of the E-ELT] is not all that much money."

Construction time

Work to build the E-ELT begins this month. The blasting of the mountain top is scheduled for June 19.

But it is expected that the Extremely Large Telescope won't be operation for another 10 years - likely too late for Professor Gilmore to try it out.

"It's an interesting feature of being involved in projects of this time scale. These big projects take 30 or 40 years from having the idea originally going through the technology development, building the political support, building the science support, getting the money, getting the engineering, through to getting it working," Gilmore says. "So unless you're lucky enough to be in one of the projects when you're relatively young, you're retired before they're in full operation. So the way I think of it is, I'm not doing this for me, it's like planting an oak forest, you're doing it for your grandchildren."