After years of planning, construction of the $1.4 billion Thirty Meter Telescope (TMT) has started in Hawaii. This gigantic next-generation telescope will provide astronomers with unparalleled power — about 10 times the resolution of Hubble — to observe the intricacies of the universe from the comfort of Earth. However, its location atop Hawaii’s Mauna Kea volcano has some local residents up in arms. It’s a case of the age-old clash of tradition with scientific progress.
As the name of the instrument suggests, the Thirty Meter Telescope will have a total reflective surface that’s 30 meters (about 98 feet) in diameter. It will actually be composed of 492 small hexagonal mirrors that serve as part of the telescope’s new “adaptive optics” system. This might be the most important innovation of the TMT because it may save us from blasting expensive telescopes into space. Well, most of the time.
The adaptive optics at work in the TMT are based on technology pioneered in the twin Keck telescopes, which are also located near the top of Mauna Kea. The Thirty Meter Telescope will be able to make fine adjustments to its focus to account for the blurring effects of Earth’s thick, soupy atmosphere. That’s why we’ve positioned telescopes like Hubble (and the upcoming James Webb Telescope) in space where the atmosphere can’t interfere with our view of the heavens.
The adaptive optics system being developed for use in the TMT uses a pair of deformable mirrors to correct for the atmospheric blurring. Essentially, the shape of the mirror itself can subtly change to correct for the effects of atmospheric turbulence in real time. Scientists call this Multi-Conjugate Adaptive Optics (MCAO). Similar to Keck, the TMT will use a wavefront sensor to sample the incoming light and determine the pattern of distortion. The telescope needs a control in order to find the right correction, which is why TMT will be equipped with the handsome laser depicted above – a powerful artificial guidestar.
TMT will give astronomers a tool powerful enough to do long term studies on dark matter, supermassive black holes, and galactic formation. It could also assist in locating exoplanets out in universe until the more specialized instruments of the Webb telescope are online.
Astronomers don’t anticipate a problem getting adaptive optics to work in the TMT — it’s essentially a scaled up version of the technology that has been successful in the Keck observatory (the Keck telescopes use 10 meter mirrors). However, protesters are expected to continue opposing the project, possibly resulting in delays. Native Hawaiians believe the slopes of volcanoes are sacred ground, and as such, should not be built upon. Protesters were able to hold up the groundbreaking ceremony briefly by blocking a road, but everything is currently on schedule for a 2022 debut.
TMT isn’t without competition in the mega-telescope sphere. A pair of projects in the Chilean Andes are already being planned that will boast 24 and 39 meter light-collecting surfaces. Each of the three big telescope projects are expected to have different specialities based on the final loadout of instruments they have. This breed of telescope is designed to investigate the biggest questions in the universe, so there’s certainly room for all three.