Credit:ESO/L. Calçada
http://www.eso.org/public/news/eso1716/

With a main mirror 39 metres in diameter, the Extremely Large Telescope (ELT) will be the largest optical/infrared telescope in the world and will take telescope engineering into new territory. It will be housed in an enormous rotating dome 85 metres in diameter — comparable in area to a football pitch [2].

One year ago, ESO signed a contract with the ACe Consortium, consisting of Astaldi, Cimolai and the nominated sub-contractor EIE Group, for the construction of the dome and telescope structure (eso1617). This was the largest contract ever awarded by ESO and also the largest contract ever in ground-based astronomy. With the laying of the first stone, the construction of the ELT dome and telescope structure has officially begun.

The ceremony also marked the connection of the Cerro Paranal and Cerro Armazones sites to the Chilean national electrical grid. This connection, which has been made possible thanks to the strong support of the Chilean Government, is managed by the Chilean Grupo SAESA. The new connection will reduce costs and provide greater reliability and stability, as well as reduce the observatory’s carbon footprint.

The ELT is the latest of many ESO projects that have benefited greatly from the continuing support of the Government of the host state of Chile over more than half a century. The strong support of the Ministry of Foreign Affairs, the Ministry of Energy and the National Commission for Energy (CNE) has been vital in establishing the successful connection of the site to the power grid.

The ELT site was donated by the Government of Chile, and is surrounded by a further large concession of land to protect the future operations of the telescope from interference of all kinds — contributing towards retaining Chile’s status as the astronomy capital of the world.

Sadly, the US TMT (Thirty Meter Telescope) languishes:

https://www.theatlantic.com/technology/archive/2016/11/hawaiis-thirty-meter-telescope-could-end-up-in-the-canary-islands/506507/

Plans for the massive observatory, originally intended to be built atop a huge shield volcano on the Big Island of Hawaii, have stalled out since last year amid a lawsuit from those who oppose the telescope project—including some Native Hawaiians, activists, and other cultural practitioners who believe the volcano, Mauna Kea, is sacred.

The Thirty Meter Telescope’s International Observatory Board decided late last month that if they cannot move forward with building the telescope in Hawaii, they will instead choose La Palma, one of Spain’s Canary Islands.

The Gran Telescopio Canarias, or Great Canary Telescope, is the massive reflecting telescope already located at La Palma. For now, it holds the distinction of being the largest single-aperture optical telescope in the world.