The construction phase of the world’s biggest optical telescope has begun atop Mauna Kea, Hawaii.
Final approval by the Hawaii Board of Land and Natural Resources for a sublease on July 25 has green-lighted building work for the Thirty Meter Telescope (TMT) to begin in October.
With a primary mirror spanning 30 meters, the TMT will dwarf all optical telescopes on Earth and in space. The twin-telescope Keck Observatory is the next biggest telescope on Mauna Kea with mirrors measuring 10 meters across. Not only will the TMT dwarf Keck, it will also be able to acquire observations 12-times sharper than the Hubble Space Telescope.
Initiated ten years ago by the Association of Canadian Universities for Research in Astronomy (ACURA), the California Institute of Technology (Caltech) and the University of California, the TMT’s international scope has expanded to include partners around the globe. Chinese and Japanese institutions are working to build components for the TNT and India is also expected to join the collaboration.
“Design of the fully articulated main science steering mirror system in the telescope, as well as development of the lasers, laser guide star systems and other high-tech components, is proceeding in China,” said Yan Jun, Director General of the National Astronomical Observatories of China, in a TNT press release.
“Japan has seen to the production of over 60 mirror blanks made out of special zero-expansion glass that does not alter its shape with temperature changes,” said Masanori Iye, TMT International Observatory Board Vice Chair and TMT Japan Representative for the National Astronomical Observatory of Japan. “The blanks will be highly polished for use in the telescope’s 30-meter diameter primary mirror. The final design of the telescope structure itself is nearing completion.”
The TMT’s 492-segment mirror will observe the Cosmos in wavelengths from near-infrared, through optical to ultraviolet, allowing us an unprecedented view of objects in our galaxy and the first stars that were forming after the Big Bang. Like Keck, the TMT will use adaptive optics (AO) to compensate for atmospheric turbulence.
AO utilizes a powerful laser that cuts through the upper atmosphere, creating an artificial star from the telescope’s perspective, detecting turbulence. It is this turbulence that is responsible for twinkling stars — interference that can blur celestial targets for telescopes on the ground. Atmospheric aberrations can then be compensated for by rapid adjustments by each telescope segment.
But to build such a huge observatory on Hawaii, special permissions were required to ensure the structure will minimize its impact on the pristine environment. But now, with this final approval, groundbreaking is scheduled to begin in a couple of months and it is hoped that we will see the first awe-inspiring observations by 2021.