Siting of a new giant telescope that will become one of the largest in the world could be switched to the Canary Islands due to continued protests over its proposed location in Hawaii. 

Astronomers are looking forward to using the Thirty Meter Telescope (TMT) as a powerful new tool with which to explore the Universe. It was due to open on the summit of Mauna Kea, on Hawaii’s Big Island, in 2022.

But the project, a collaboration between California, Canada, Japan, China and India, has been beset with problems, with native Hawaiian protestors unwilling to see another instrument on what they consider to be sacred land.

Though a permit for the giant telescope’s construction was given by the Hawaiian Board of Land and Natural Resources in 2013, demonstrators have repeatedly halted attempts to begin construction. Then, in December 2015, the permits were ruled invalid by Hawaii’s Supreme Court which decided that due process had not been followed.

Now the authorities behind the project have revealed that they are ready to consider alternative sites for the giant telescope, and leading contender as a replacement location is the island of La Palma, off the west African coast.

The island is claimed to be the steepest in the world, and the 2,426-metre (7,960 ft) high ridge of its central caldera is already home to a number of major telescopes including the 10.4-metre GranTeCan, which is currently the largest optical telescope in the world.

They were established after site-testing in the 1970s showed that the location enjoys clear skies and remarkably steady atmospheric conditions thanks to prevailing winds from the west flowing uninterrupted over thousands of miles of sea.

Announcing the decision, Henry Yang, Chair of the TMT International Observatory Board, said: “The TMT International Observatory Board of Governors has explored a number of alternative sites for TMT. Every site we considered would enable TMT’s core science programs.

“After careful deliberation, the Board of Governors has identified Observatorio del Roque de los Muchachos (ORM) on La Palma in the Canary Islands, Spain as the primary alternative to Hawaii.

“Maunakea continues to be the preferred choice for the location of the Thirty Meter Telescope, and the TIO Board will continue intensive efforts to gain approval for TMT in Hawaii. TIO is very grateful to all of our supporters and friends throughout Hawaii, and we deeply appreciate their continued support.”

TMT supporters had hoped the telescope would become the biggest optical telescope in the world for a time before the European Extremely Large Telescope (E-ELT) opens its eye on the sky a couple of years later in Chile. That will have a main mirror, or “eye on the sky” 39.3 metres (nearly 130 ft) across and now looks likely to be completed first.

How the Thirty Meter Telescope will help astronomers learn more about the Universe. Credit: TMT Observatory Corporation

The TMT, operating in wavelengths ranging from the ultraviolet to the mid-infrared, will help astronomers understand star and planet formation, unravel the history of galaxies and learn how large-scale structure in the Universe developed.

The giant telescope within its striking dome will be of Ritchey-Chretien design, with a main mirror that is a mosaic of 492 separate segments to collect faint starlight from the depths of the Universe. It will have 144 times the collecting area of the Hubble Space Telescope.