An international effort to build an enormous telescope in Hawaii that would see to the limits of the known universe has taken an important step forward, a signal that the Harper government will have to decide soon if Canadian astronomers will have a share in the instrument's future discoveries.

On Monday, the Thirty Meter Telescope (TMT) project announced it had obtained permits and approval of a sublease by state authorities to build a huge new observatory atop Mauna Kea, an extinct volcano on the big island of Hawaii that boasts some of the world's leading astronomical facilities.

The telescope's primary mirror will be 30 metres across, giving it about half the surface area of an NHL hockey rink. Such an instrument would easily dwarf any telescope operating in the world today and help usher in a new era of cosmic exploration.

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Canada has invested $30-million in the telescope's design and development, but it is not yet an official partner in the project. That would require an additional $300-million to secure a 20 per cent share in the $1.5-billion telescope.

With austerity ruling the federal budget process in recent years, there's been little reason to expect Ottawa to rush to commit so much money. With the project moving forward, there may be little time to lose.

"We still have the opportunity to join the TMT, but funding will need to be committed by April, 2015, if we are not to lose our current stake in the project," said Christine Wilson, a professor of astronomy at McMaster University in Hamilton and president of the Canadian Astronomical Society, which represents professional researchers in the field nationally. In 2010, the society identified TMT as its top-ranked scientific priority.

While the telescope is not expected to be completed before 2023, Canada's status could become urgent within months because half of its proposed contribution is slated for building a spherical enclosure – a crucial early step.

"You can't put the telescope up until there's something to protect it," said Ray Carlberg, a University of Toronto astronomer and Canadian spokesman for TMT.

If Canada joins TMT, building the enclosure will fall to Dynamic Structures of Port Coquitlam, B.C.

The remainder of Canada's contribution would go to the National Research Council to build the computer-control optical components that would allow the telescope to preserve its image quality despite the distorting effects of Earth's turbulent atmosphere.

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Japan and a consortium of California universities have already committed to TMT. India and China are moving toward full partnership.

The project reflects a trend in astronomy toward super-sized observatories supported by multinational collaborations. Earlier this year, a consortium of mainly European nations began building a 39.3-metre telescope in Chile.

The giant telescopes will be used to probe the universe at a time when the first galaxies were forming. They will also be powerful enough to reveal the properties of planets circling distant stars.

But with only two or three such instruments expected to be built in the next half century, Canada has a limited window in which to find a partnership that works.

Scott French, a spokesman for the Ministry of State for Science and Technology, said the Canadian team working on TMT has been invited to put forward a proposal under the new Canada First Research Excellence Fund, which was announced in the 2014 federal budget. He added that assessment of proposals will begin "later this year."

Gordon Squires, a spokesperson for TMT based at the California Institute of Technology in Pasadena, said work on the telescope has been accelerated.

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"We'll be looking very carefully, obviously, at what happens in the next [Canadian federal] budget, but in the interim, the project has a plan to begin construction and take it to the next step and that's the plan we'll follow," he said.