Cerro Armazones is a crumbling dome of rock that dominates the parched peaks of the Chilean Coast Range north of Santiago. A couple of old concrete platforms and some rusty pipes, parts of the mountain’s old weather station, are the only hints that humans have ever taken an interest in this forbidding, arid place. Even the views look alien, with the surrounding boulder-strewn desert bearing a remarkable resemblance to the landscape of Mars.
Dramatic change is coming to Cerro Armazones, however — for in a few weeks, the 3,048m mountain is going to have its top knocked off.
“We are going to blast it with dynamite and then carry off the rubble,” engineer Gird Hudepohl said. “We will take about 80 feet [24.3m] off the top of the mountain to create a plateau and when we have done that, we will build the world’s biggest telescope there.”
Given the peak’s remote, inhospitable location, that might sound an improbable claim — except that Hudepohl has done this sort of thing before. He is one of the European Southern Observatory’s (ESO) most experienced engineers and was involved in the decapitation of another nearby mountain, Cerro Paranal, on which his team then erected one of the planet’s most sophisticated observatories.
The Paranal complex has been in operation for more than a decade and includes four giant instruments with 8m mirrors — known as the Very Large Telescopes (VLTs) — as well as control rooms and a labyrinth of underground tunnels linking its instruments. More than 100 astronomers, engineers and support staff work and live there.
A few dozen meters below the telescopes, they have a sports complex with a squash court, an indoor soccer pitch and a luxurious 110-room residence that has a central swimming pool and a restaurant serving meals and drinks around the clock. Built overlooking one of the world’s driest deserts, the place is an amazing oasis.
Now the ESO, of which Britain is a key member state, wants Hudepohl and his team to repeat this remarkable trick and take the top off Cerro Armazones, which is 20km distant. This time they are to construct an instrument so huge it would dwarf all the telescopes on Paranal put together and any other telescope on the planet.
When completed, the European Extremely Large Telescope (E-ELT) and its 39m mirror are to allow astronomers to peer further into space and look further back into the history of the universe than any other astronomical device in existence. However, its construction will push telescope-making to its limit. Its primary mirror will be made of almost 800 segments — each 1.4m in diameter and only a few centimeters thick — that will have to be aligned with microscopic precision.
It is a remarkable juxtaposition: In the midst of utter desolation, scientists have built giant machines engineered to operate with smooth perfection and are now planning to top this achievement by building an even more vast device. The question is: for what purpose? Why go to a remote wilderness in northern Chile and chop down peaks to make homes for some of the planet’s most complex scientific hardware?
The answer is straightforward, Cambridge University astronomer professor Gerry Gilmore said: It is all about water.
“The atmosphere here is as dry as you can get and that is critically important. Water molecules obscure the view from telescopes on the ground. It is like trying to peer through mist — for mist is essentially a suspension of water molecules in the air, after all, and they obscure your vision. For a telescope based at sea level that is a major drawback,” Gilmore said.