The United States is to commit $1.6 billion to building a “massive telescope” that will usher American astronomy into a new era, according to the National Science Board, which advises the National Science Foundation.
In a statement on Feb. 27, the board gave the foundation until May to decide how to choose between two competing proposals for the telescope. The announcement came as a relief to American astronomers, who were worried about losing ground to their European colleagues in an effort to survey the sky with bigger and better telescopes.
But which of the two telescopes will be built — and the fate of the dreamer and the billions of dollars worth of time and technology already invested — remains an open question. Many astronomers hope that the foundation, the traditional financier of national observatories, will find a way to invest in both projects.
The two projects are the Giant Magellan Telescope at Las Campanas in Chile and the Thirty Meter Telescope, possibly destined for Mauna Kea on the island of Hawaii, also known as the Big Island. Both will be larger and more powerful than any telescope currently on Earth or in space. Each is expected to cost about $3 billion or more, and less than half of the projected cost has been raised so far by the international partnerships that support them.
In an announcement that circled astronomers, the board said funding even one telescope at a price point of $1.6 billion would take up most of NSF’s usual budget for construction.
“Furthermore, the priorities of the astronomy and astrophysics community must be considered in the broader context of the high-priority, high-impact projects for many disciplines that NSF supports,” the board said in the statement. this last week.
For now, astronomers with a stake in the outcome are careful to note that Congress, as well as the White House and the science foundation, will eventually have their say.
“This is a marathon, not a sprint,” said Robert Kirshner, director of the Thirty Meter Telescope International Observatory and former member of the Giant Magellan team. He added that he hopes both telescopes can continue.
Michael Turner, an emeritus cosmologist at the University of Chicago and former assistant director for physics and astronomy for the NSF, called the recent development “great news for US astronomy and sees “a realistic path forward” for a very large telescope.
“Before you know it, the telescope will be dazzling us with images of exoplanets and the early universe,” he said. “Should it have happened faster? Of course, but that’s history. Full speed ahead, eyes on the future!”
Wendy Freedman, a cosmologist at the University of Chicago who led the Giant Magellan project in its first decade, said in an email: “I’m glad that NSB has decided to fund an ELT. I think that the worst outcome is not to fund any ELT; that would be a tragedy! Frankly (and unfortunately), there is no budget for both. But an ELT is critical for the future of US astronomy.
He added, “So I’m very relieved.”
Robert Shelton, president of the Giant Magellan collaboration, said: “We respect the recommendation of the National Science Board to the National Science Foundation and remain committed to working closely with NSF and the astronomical community to ensure the successful realization” of a very large telescope , “which will enable innovative research and discovery for years to come.”
But Richard Ellis, an astrophysicist at University College London who was one of the early leaders of the Thirty Meter Telescope project, told Science“It’s a tragedy, given the investment made in both telescopes.”
A telescope’s power to see deeper and fainter objects in space is largely determined by the size of its primary mirror. The largest telescopes on Earth are eight to 10 meters in diameter. Giant Magellan will group seven eight-meter mirrors to make the equivalent of a 25-meter telescope; the seventh and final glass was cast last year, and workers are ready to pour concrete at the site in Las Campanas.
Thirty Meter will consist of 492 hexagonal mirror segments, which scale up the design of the twin 10-meter Keck telescopes operated on Mauna Kea by the California Institute of Technology and the University of California. (The 100th segment has just been cast in California, but protests by Native Hawaiians and other critics have prevented any work at the TMT site on Mauna Kea; the project team is considering a alternative site in the Canary Islands.) Neither telescope is likely to be ready until the 2030s.
Even as the American-led effort moves forward, the European Southern Observatory is building a very large telescope — called the Extremely Large Telescope — at the Paranal Observatory in Chile. Its main mirror, consisting of 798 hexagonal segments, will be the largest and most powerful of all — 39 meters in diameter. It will also be the first of the competitors to complete; European astronomers plan to begin using it in 2028. If the effort is successful, it will be the first time in a century that the largest working telescope on Earth will not be on American soil.
Both the Giant Magellan and the Thirty Meter telescopes are multinational collaborations headquartered a few miles apart in Pasadena, Calif.
Support from the NSF has been a point of contention between the two groups since their inception 20 years ago.
In 2019, the two groups agreed to join forces to create an American ELT program, under the auspices of the National Optical-Infrared Research Laboratory in Tucson, Ariz., that would allow American astronomers to use the same telescopes. . Astro 2020, a blue-ribbon panel of the National Academies of Science, endorsed the proposal, calling it a top priority in ground-based astronomy for the decade. The panel recommended that the science foundation chip in $1.6 billion to buy an ownership stake in one or both of the telescopes.
But the costs of these telescopes continued to rise, and the $1.6 billion didn’t come close. And the wheels of the scientific community and the federal government are turning slowly.
“That process takes three to five years,” said Linnea Avallone, chief officer for research facilities at NSF “We’ve been committed for just one year. I don’t think we’re dragging our feet; I don’t think we’re being aggressive. He added that the foundation is “very good stewards of taxpayers’ money.”
Did he see a danger in the United States not funding its own Extremely Large Telescope?
“That’s a good question, better answered by astronomers,” said Dr. Avallone.