If you’ve ever observed the Milky Way at night, you might have noticed its cloud-like appearance. This is due to the abundant dust near the galaxy’s center, which obscures much of the universe from view. About half of the light from galaxies is hidden by this dust. To see into these obscured regions, a large submillimetre-wave telescope, which detects radiation between radio waves and infrared, is ideal.
“Without submillimetre, we’re getting a very biased picture of what’s out there,” said Claudia Cicone, an astrophysicist at the University of Oslo, Norway. “We are missing the regions of space that are most obscured by dust.”
Telescopes like the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have begun to probe these regions. Now, astronomers plan to advance further with the European-led Atacama Large Aperture Submillimeter Telescope (AtLAST), a 50-meter telescope larger than any before.
The EU-funded AtLAST2 project, running until 2028, is in its early design phase. Researchers from Europe and worldwide, including Chile, South Africa, and the USA, are developing the project’s concept by prototyping technologies and planning for sustainable operations.
The goal is to bring the hidden universe into focus. “With previous submillimetre facilities, we’re observing the tip of the iceberg,” said Cicone. Currently, astronomers see only a fraction of the cold gas and dust shaping galaxies.
“With AtLAST, we will answer the question of where all the gas and dust in the universe is.”
AtLAST aims to join a new generation of giant observatories in the 2040s, complementing Europe’s Extremely Large Telescope in Chile. Without a large, single-dish submillimetre telescope, astronomical mapping of cold gas and dust would be incomplete.
ALMA’s antennas act like a microscope, providing detailed views of dusty star-forming regions. In contrast, AtLAST would serve as a wide-angle camera, surveying dusty locations across the universe.
“ALMA can only see an area much smaller than the Moon’s surface in any observation,” said Tony Mroczkowski, an astronomer at Spain’s Institute of Space Sciences and an AtLAST lead. “AtLAST will image an area up to 16 Moons in size with each observation, enabling extensive mapping.”
The telescope needs to move quickly across the sky with a large field of view. The AtLAST2 team is prototyping crucial components, including optics and control systems, for efficient sky mapping.
The primary 50-meter dish will feature aluminum panels and a steel backing, weighing about 4,400 tonnes. A 12-meter secondary mirror will enhance its field of view. AtLAST will be located near ALMA in the Atacama Desert, benefitting from clear views due to the high, dry atmosphere.
“The telescope will be powered entirely by renewable energy, using hybrid regeneration,” said Cicone. By recovering kinetic energy after movement, like a hybrid car, the project plans to run without fossil fuels, using solar power and energy storage methods.
Collaboration with Japan, which previously considered its 50-meter dish, will further international support for AtLAST. “We realized that we should join forces,” said Cicone.
AtLAST’s survey could uncover hidden cold gas and dust, obscured galaxies, and unseen solar atmosphere components. “We can study the solar atmosphere and solar flare variability like never before,” said Cicone.
AtLAST would explore dusty regions where individual galaxies are currently indistinguishable. This could potentially identify up to 50 million galaxies in 1,000 hours of observations.
“With AtLAST’s huge field of view, we would create large maps of the submillimeter sky extremely quickly,” said Mroczkowski.
This mapping will help understand the universe’s evolution, dark energy’s role in its expansion, and the nature of dark matter. It may also reveal the universe’s missing matter, such as hard-to-find hot and cold gas around galaxies.
By identifying molecules that could be life’s building blocks, AtLAST might explain life’s emergence and evolution in the universe. Observations of gas and dust around young stars could offer insights into star and planet formation.
Unexpected discoveries, like new transient events revealed at submillimetre wavelengths, could arise. AtLAST is designed for a 50-year lifespan, allowing for long-term scientific exploration.
The aim is to create a long-lasting, upgradeable telescope benefiting future generations of astronomers, said Mroczkowski.
Research in this article was funded by the EU’s Horizon Programme. The views of the interviewees don’t necessarily reflect those of the European Commission. If you liked this article, please consider sharing it on social media.
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