A new European-led telescope could map the dusty hidden half of the universe without using any fossil fuels.
If you’ve ever seen the Milky Way in the night sky, you’ve probably noticed that it appears cloudy. That’s because toward the center of our galaxy, and most galaxies, there is an enormous amount of dust that makes it difficult to see what’s going on.
This means that large areas of the universe are hidden from our eyes, and about half of the light comes from galaxies buried in dust. The best way to see inside these hidden regions is with giant submillimeter telescopes, which detect radiation between radio and infrared waves.
“Without submillimeter, we get a very biased picture of what’s out there,” said Claudia Ciccone, an astrophysicist at the University of Oslo in Norway. “We’re missing the regions of space that are most hidden by dust.”
In recent decades, telescopes like the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile have made it possible to explore some of these regions.
Now, astronomers hope to go further with a new European-led project called the Atacama Large Aperture Submillimeter Telescope (AtLAST). This is a 50-meter telescope, much larger than any submillimeter telescope ever built.
Initial design work is being carried out in an EU-funded project called AtLAST2, which will run until 2028. Researchers in Europe and around the world, including Chile, South Africa, Canada, Taiwan, Thailand, New Zealand, Japan and the United States, are refining the concept by prototyping key technologies and planning how to run the facility as sustainably as possible.
The aim is to focus on that cloudy hidden universe. “With previous submillimeter facilities, we are only observing the tip of the iceberg,” said Ciccone, one of the telescope’s leaders. Astronomers can currently only see a tiny fraction of the cold gas and dust that makes up galaxies.
“With AtLAST, we can answer the question: Where is all the gas and dust in the universe?”
AtLAST is designed to be part of a new generation of giant observatories set to reshape astronomy in the 2040s, following Europe’s Very Large Telescope, which is nearing completion in Chile.
Without these large, single-plate submillimeter telescopes, astronomers say there would be a big gap in their ability to map cold gas and dust across the sky and connect what these other facilities see at different wavelengths.
wide angle view
ALMA’s 66 antennas in the Atacama Desert act like microscopes, focusing on the dusty regions where stars and planets form. In comparison, AtLAST is a wide-angle camera, capable of surveying dusty locations throughout space.
“ALMA can only see an area of the sky thousands of times smaller than the moon’s surface in any given observation,” said Tony Mroczkowski, an astronomer at the Spanish Institute of Space Sciences and one of the leaders of AtLAST.
“Alma is powerful, but it can’t map the sky with a microscope. In comparison, AtLAST images regions the size of up to 16 moons with each observation, so we can map everything in the universe,” he joked.
To map the sky at that scale, the telescope “has to move rapidly back and forth across the map,” Mroczkowski said. “If you have a large field of view, you can quickly create a fairly large map of the sky.”
The AtLAST2 team is using this design phase to prototype key parts of the telescope, from optics and control systems to data processing.
BUILT TO LAST
AtLAST’s main 50 meter dish will be designed with mirrored aluminum panels and a massive steel back structure. It weighs approximately 4,400 tons and incorporates a 12-meter secondary mirror, larger than most telescopes, to provide a wide field of view.
It will be located near ALMA in the Atacama Desert, where the thin, dry atmosphere more than 5 km above sea level allows for pristine views of the universe.
“The telescope will be powered entirely by renewable energy, using a new customized hybrid energy recovery,” Ciccone said. The telescope decelerates after moving, allowing it to recover kinetic energy as a charge, much like a hybrid car.
The project is testing a combination of solar power generation, battery and metal hydride energy storage, and braking energy recovery to operate a power-hungry 50-meter-tall observatory at a remote high altitude without using fossil fuels.
The researchers also plan to use near-zero carbon electricity to produce steel and aluminum. It is hoped that AtLAST2 will set a pattern for how large observatories can carry out ambitious science without jeopardizing Europe’s climate goals.
The project will involve several countries, including Japan, which previously considered building its own 50-meter submillimeter antenna, the Large Submillimeter Telescope (LST).
“We realized we needed to work together,” Ciccone said.
The AtLAST2 project aims to turn that close cooperation into a concrete shared facility, bringing together European expertise and partners from around the world.
hidden galaxy
AtLAST’s research could reveal the cold gas and dust that fuels star formation, previously hidden dust-covered galaxies, and even invisible components of the Sun’s atmosphere. “We can now study the variability of the solar atmosphere and solar flares in a way that has never been done before,” Ciccone said.
In the case of galaxies, AtLAST peers into particularly dusty regions of space where galaxies are currently hidden. Astronomers can detect light from these regions, but the individual galaxies are blurred together and it’s impossible to know how many there are.
“We don’t know whether the light is coming from one galaxy, 10 galaxies, or 1,000 galaxies,” Ciccone said, referring to the so-called confusion limit. AtLAST could recover these lost galaxies and discover up to 50 million in 1,000 hours of observation, she said.
This will help astronomers understand how the universe has evolved over cosmic time, helping determine the accelerating expansion of the universe due to dark energy and the nature of dark matter, the invisible matter whose gravity shapes galaxies.
Using wavelengths in the traditional visible range could also reveal much of the matter missing in the universe, including both hot and cold gas that should exist around galaxies but has proven difficult to detect.
By discovering molecules that may be the building blocks of life, AtLAST could help astronomers understand how life originates, develops and evolves in the universe, Mroczkowski said.
By peering into molecular clouds and debris disks (regions of gas and dust around young stars), scientists will also gain deeper insight into how stars and planets form.
Perhaps the greatest science comes from the unknown. It’s unexpected discoveries, such as new transient and short-lived events that only appear at submillimeter wavelengths and that only AtLAST’s wide field of view can reveal. AtLAST is designed to operate for 50 years, so there will be plenty of time to unravel these mysteries.
Mroczkowski said the goal is to make it “not just a disposable telescope, but a telescope with long-life, upgradeable instruments that will benefit future generations of astronomers.”
This article was originally published in Horizon, EU Research and Innovation Magazine.
The research for this article was funded by the EU’s Horizon program.
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