Hawaii's Board of Land and Natural Resources (BLNR) has granted a construction permit for the protest-hit $1.4bn Thirty Meter Telescope (TMT). The BLNR's board, which voted 5-2 in favour, places 43 conditions on the construction including that employees have at least one day's cultural and natural resources training and that the TMT officials implement an invasive-species control programme.

When built, the TMT will be one of the world's largest ground-based telescopes with a 30 m primary mirror that is made up of 492 hexagonal segments. The structure that will house the telescope will be 66 m wide and 56 m tall. Mauna Kea was chosen as the observatory's site in July 2009 and over the following six years, the TMT organization received a series of necessary approvals and permits. However native Hawaiians, who regard the Mauna Kea summit as sacred – and who had previously objected to the growth in the number of telescopes there – carried out a protest at the telescope's ground-breaking in October 2014.

Further demonstrations

Six months later, following further demonstrations, construction was postponed. Then in December 2015, the Hawaiian Supreme Court invalidated the TMT's building permit, ruling that the BLNR had not followed due process when it was approved. Meanwhile, TMT chose La Palma in the Canary Islands as a back-up site earlier this year.

The court then remanded the case back to the board, who appointed retired judge Riki May Amano to re-hear it. In July, Amano recommended that the BLNR reissue the permit, so long as a number of conditions are met including that the building work abides by government rules.

With the approval by the BLNR, building work on the TMT could now begin in April 2018 with completion by 2022.