Mauna Kea was selected this week by a board of advisors in charge of deciding where to site the Thirty Meter Telescope (TMT), the first of the next generation of giant ground-based telescopes. After a multi-year site review process by the TMT Corporation–including detailed satellite, weather and environmental studies–Hawaii and Chile were to top  contenders for locating the TMT, which could be built and operational as soon as 2018.  Hawaii won out over Chile as the best site because of slightly better atmospheric conditions, very low humidity and lower temperatures. Existing nearby observatories, such as Keck, Subaru, Gemini and the UH, will be useful for collaborations with TMT and were also an important factor.

In the official statement released today by TMT Corporation, the board of directors who selected Mauna Kea over Chile expressed “a strong commitment to respect the long history and cultural significance of Mauna Kea to the Hawaiian people, and has committed annual funding for local community benefits and education in Hawai‘i.” There has been strong opposition among some groups to any scientific activity at the summit. Exactly how much funding, for what specifically and who will receive was not disclosed.

Before construction can begin on Mauna Kea, the TMT must submit and have approved an application for a Conservation District Use Permit (CDUP) to the Hawaiian Department of Land and Natural Resources. This will be done through the community-based Office of Mauna Kea Management, which oversees the Mauna Kea summit as part of the University of Hawai’i at Hilo.

In addition to cultural and environmental concerns, weather plays a major role in the success of any observatory. Specifically, lack of it makes for better observing conditions for astronomers. Twinkling stars, a beautiful phenomenon to watch from the backyard, is a problem for astronomers because the twinkle signals humidity in the upper layers of Earth’s atmosphere. Atmospheric humidity interferes with light hitting the reflecting mirrors inside telescopes, causing distortion.

The problem of light distortion gets more detrimental as a telescopes mirror get bigger, a problem that could render data utterly useless from a telescope as big as the TMT will be. Current large telescopes, such as Gemini and Keck, use a method called “adaptive optics” to adjust for twinkle. Engineers for the TMT  are developing a special distortion correction system that will cover the TMT’s 492 segmented mirrors.