Construction has begun on a generational scientific installation, the Thirty Meter Telescope (TMT), to be assembled at altitude in Mauna Kea, Hawaii over the next decade with a significant Canadian contribution.
The much-delayed $1.4-billion project was given the go-ahead by Hawaii Gov. David Ige on June 10 with road closings permitting the non-profit project owner, the Thirty Meter Telescope International Observatory (TIO), to begin transportation of heavy equipment to the jobsite July 15.
When completed in an estimated 10 years, the TMT with its 30-metre diameter lens will have nine times the light-gathering power of the current generation of telescopes, permitting images more than 12 times the resolution at certain wavelengths of the Hubble Space Telescope.
Canada’s National Research Council (NRC) is partnering with the University of California, the California Institute of Technology (Caltech) and other government research institutions from China, India and Japan as members of TIO.
Astronomer Luc Simard is the director general of the NRC’s Victoria-based Herzberg Astronomy and Astrophysics Research Centre, in charge of delivering Canada’s three contributions to the project.
The Canadian design is the best one…so it will really be the key to the success of TNT,
— Luc Simard
Herzberg Astronomy and Astrophysics Research Centre
“It is very exciting,” said Simard recently. “Personally, my first telescope was 15 centimetres, so the idea that we are now able to deploy a 30-metre telescope on the sky to make all these wonderful discoveries is tremendously exciting.
“The science is extremely motivating for everybody involved, we are talking anything from viewing the very first stars in the universe to potentially the detection of life elsewhere beyond the solar system.”
Canada’s three deliverables are a dome that will house the telescope, precision-engineered with a unique “calotte” enclosure system; the project’s adaptive optical system, which sharpens images collected by the telescope similar to a pair of glasses; and scientific instrumentation including an infra-red imaging spectrometer (IRIS), developed in collaboration with other researchers, that will permit viewing and analysis of images beyond anything currently in existence.
The dome is being designed by the firm Dynamic Structures based in Port Coquitlam, B.C. to enable proper operation of the high-precision mirrors and instruments, starting with M1, the primary mirror. Simard explained M1 is not one 30-metre piece of glass but rather 492 segments, each 1.4 metres in diameter, that are controlled by individual mechanical hands with 26 fingers each.
“The enemy of a large telescope is the wind,” he said. “If you do not property shield the telescope from the wind, the wind shaking the telescope will ruin the image quality. So you need a dome that does this really well. And the Canadian design is the best one for that purpose so it will really be the key to the success of TNT.”
Early incarnations of protective shells might have “barn doors” that require significant space but the callote design, with the aperture and the telescope working in tandem, offers maximum efficiency, Simard explained. It has two components, the base and the cap. The base sits on a horizontal track and turns around horizontally. The cap is on an inclined track and rotates at an angle.
“The combination of the two allows you to point the aperture of the dome anywhere in the sky,” Simard said, noting that for some applications the telescope has to be in position within five minutes. “The aperture is only slightly larger than the telescope diameter so it’s a pretty good shield from the wind.”
The construction timetable posted on the TMT site is way off, Simard acknowledged; he said delays are part of the process. Previous attempts to start construction were thwarted by indigenous and environmental protestors and at one point the construction permitting process went back to square one. Last October, the Hawaii Supreme Court issued a decision affirming the regulator’s authority to issue a Conservation District Use Permit for construction.
Protesters were back on site when construction relaunched July 15. The Plan B site is in the Canary Islands.
Later on into next decade — Simard says he plans to still be involved with the project at that time — the sensitive Canadian optical instrumentation will be ready for installation.
“The instruments are last in the construction timeline but they have a direct link to the first stage. The dome and the site, everything is interconnected, so that is why you have a strong team of engineers that are always looking at the big picture so these pieces come together,” he said.
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