E-ELT construction work begins

Building work on ESO's E-ELT, the world’s largest telescope, begins this week

The European Extremely Large Telescope (E-ELT) programme office has studied half a dozen potential sites for the future E-ELT observatory, which, with its 40-metre-class diameter, will be the world’s biggest eye on the sky. Various aspects need to be considered in the site selection process. Parameters taken into account are not restricted to ‘sky quality’, but include more general scientific aspects, as well as parameters essential for construction and operations (e.g. accessibility, water and power supply, political stability etc.). The above picture shows Cerro Armazones at sunset. Armazones is a site located in Chile, not very far from the ESO Paranal Observatory, home to the flagship Very Large Telescope. On the E-ELT Site Selection Advisory Committee's final short list for the recommended site, Armazones is also the committee’s preferred site, because it has the best balance of sky quality across all aspects and can be operated in an integrated fashion with the existing Paranal Observatory.

The Cerro Armazones mountain in Chile is the intended site for the E-ELT. Credit: ESO


Construction of the world’s largest telescope will start with a bang this Thursday.

Demolition crews have already set explosives to blast the top off the Cerro Armazones mountain in Chile where the observatory will be built.

The European Extremely Large Telescope (E-ELT) will be a massive 39m telescope built by the European Southern Observatory (ESO) in Chile’s Atacama desert.

Once finished the telescope will be able to directly image exoplanets, possibly Earth-like ones, and will also be able to detect the earliest galaxies in our Universe.

In order to house the telescope a huge dome needs to be constructed but before building work can even begin, the crew must first level out the top of the mountain.

“We need to remove 70m from the top of the mountain to achieve the minimum size of the flat platform to host the telescope and its dome,” says Roberto Tamai, programme manager for the E-ELT.

“The real work started a couple of weeks ago, with bulldozers on top.

Before they do the blasting we needed to remove the first layer of ground and get rid of all the loose pieces before we reach the real rock.”

After the first blast on Thursday there will be several more before the site is ready.

All going well, the telescope’s foundations will be laid by 2017.

However it will still be another 10 years before the project is finished, as both the telescope and dome require a huge amount of precision engineering.

The primary mirror is so large, over 39-metres in diameter, that it’s not possible to build it in one piece. Instead the mirror will be made of 798 hexagonal segments.

To get it ready for the 2024 deadline, researchers around the world have already begun testing the technology needed to build the massive telescope.

“We’ve been building some of the science equipment, mostly prototypes of things like the primary mirror segments, the supports and some of the secondary mirrors,” says Tamai.

“The biggest challenge in terms of engineering is the precision requested for something this size.


We’ve tested most of the components, but what’s left is to put them together on such a big machine.”