A new ten-year plan for the cosmos


US astronomers on Thursday called on the nation to invest in a new generation of multibillion-dollar “extremely large” telescopes that would be larger than any currently on Earth or orbiting space.

The investment would involve bailing out and combining the efforts of two rival projects, the Giant Magellan Telescope and the Thirty Meter Telescope. When completed, these telescopes, with primary collection mirrors 25 and 30 meters in diameter, would be about 100 times more sensitive than any telescope currently in operation.

They would allow astronomers to peer deeply into the nuclei of distant galaxies, where monstrous black holes roam and emit energy; investigate mysteries like dark matter and dark energy; and study planets around stars other than the sun. Perhaps more importantly, they could raise new questions about the nature of the universe.

But astronomers have struggled for years to raise enough money to make their dreams come true. In the new proposal, the National Science Foundation would provide $ 1.6 billion to complete the two projects and then help run them under a new program called the United States Extremely Large Telescope.

Astronomers on Thursday also urged NASA to embark on a new mission of large observatories and a technology maturation program that would develop a series of astrophysical spacecraft over the next 20 to 30 years. The first would be an optical telescope larger than the Hubble Space Telescope and capable of finding and studying Earth-like planets – potentially habitable “exo-Earths” – in the nearby cosmos. Only NASA could accomplish this, the astronomers said, noting that it could be ready by 2040 and would cost $ 11 billion.

These two recommendations were the most important in a long-awaited 614-page report, Pathways to Discovery in Astronomy and Astrophysics for the 2020s, released Thursday by the National Academies of Sciences, Engineering and Medicine.

Every 10 years for the past 70 years, the academy has sponsored a survey of the astronomical community to set priorities for big-ticket items over the next decade. The Decadal Survey, as it’s called, is drawing the attention of Congress, NASA, the National Science Foundation, and the Department of Energy.

This year’s effort – chaired by Fiona A. Harrison of the California Institute of Technology and Robert C. Kennicutt, Jr., of the University of Arizona – spanned three years and required dozens of meetings and discussions. between 13 sub-groups covering all branches of astronomy. A total of 860 white papers were submitted to the survey, describing telescopes that could be built, space missions that should be launched, experiments or observations that should be made, and issues such as diversity that the community astronomical should address.

In an interview, Dr Harrison said their committee tried to balance ambition against the time and money these projects would take. For example, several ideas have been launched for a planetary prospecting spacecraft. Some were too big, others too small; some would take a century to complete. Rather than pick one of them, the group asked the community and NASA to come back with ideas for a six-meter-diameter space telescope. (Hubble’s main mirror is 2.4 meters in diameter.)

“A six-meter telescope appears to be an achievable ambition,” said Dr Harrison.

“It is an ambitious quest by nature,” she added. “Only NASA, only the United States can do it. We believe we can do it.

Matt Mountain, president of the Association of Universities for Astronomical Research, or AURA, which manages observatories for the National Science Foundation, described the 10-year report as “rather bold” in an email. “And they didn’t hesitate to articulate a vision over several decades, which in reality is what it takes and must take.”

The ten-year surveys have been successful. The Hubble Space Telescope, launched in 1990 and still in operation, and the James Webb Space Telescope – designed to see until the beginning of time and scheduled to launch next month – have enjoyed high rankings in Decadal Surveys previous ones.

The results of each new investigation are therefore eagerly awaited by the astronomical and astrophysical community. “The committee has been extremely secretive,” Natalie Batalha, a professor at the University of California at Santa Cruz, who played a leading role in NASA’s Kepler planet search mission, said in an email. on the eve of publication of the report. “I didn’t hear anything, honestly. I’m on pins and needles waiting.

In its Thursday report, the academy listed three overarching scientific goals for the next decade: the search for habitable and living planets; the study of black holes and neutron stars, responsible for the most violent natural events; and the growth and evolution of galaxies.

“The decades to come will put humanity on the path to determining whether we are alone,” the report said. “Life on Earth may be the result of a common process, or it may require such an unusual set of circumstances that we are the only living things in our part of the galaxy, or even in the universe. Either answer is profound.

The idea of ​​an extremely large telescope program is ambitious, as it involves the blending of two rival telescope projects, the thirty-meter telescope, planned for the summit of Mauna Kea in Hawaii or the Canary Islands in Spain, and the Giant Magellanic Telescope underway in Chile.

The two telescopes are the dream products of sprawling international collaborations and two decades of fundraising and recruiting partners. Either telescope would be about three times the size of anything on Earth today and 100 times more capable of discerning distant faint stars in the cosmos; working together, they could tackle deep questions about the cosmos. But neither of the two projects raised enough money – more than $ 2 billion is needed – to meet their goals.

Failure to build these telescopes would cede the leadership of ground astronomy to Europe, which is building a 39-meter telescope – the extremely large European telescope, in Chile’s Atacama Desert – which is expected to start operate in 2027. Some astronomers have compared the situation to the cancellation of the American Superconducting Supercollider project in 1993, which entrusted the future of particle physics to CERN and the Large Hadron Collider in Geneva.

If the National Science Foundation were to invest in completing the two telescopes, it would gain significant observation time on them, which would be distributed to American astronomers.

“The two telescopes, being in opposite hemispheres and with radically different designs, would be perfectly suited for complementary interrogations of the cosmos,” said Dr Harrison. “To imagine that the United States would not have access to it is unthinkable. “

Major challenges await you. The Giant Magellan team has already broken new ground in Chile, but progress on the thirty-meter telescope has been hampered by protests and blockades from indigenous Hawaiian groups and others. An alternative site has been designated at La Palma in the Canary Islands.

Astronomers are hoping the stars will align for their bold vision, given the current focus on infrastructure and increasing science budgets. But they’re haunted by a history of cost overruns, most notably with the James Webb Space Telescope, which will finally launch in December after years of delay and with a final price tag of $ 10 billion.

“JWST looms above all of that – the whole program will be based on its success,” said Michael Turner, a cosmologist now at the Kavli Foundation in Los Angeles and a ten-year survey veteran. “Crossed fingers.”

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