A 50-meter telescope on the high slopes of the Atacama Desert could soon reveal the half of the universe we cannot see—and build it entirely without burning fossil fuels. That cloudy, dust-choked half is not poetic metaphor but literal cosmic reality: roughly half of all light from galaxies arrives at Earth filtered through vast clouds of dust that render them invisible to conventional observation. Without a way to penetrate these obscured regions, astronomers are missing entire categories of celestial objects and stellar nurseries that shape our understanding of how the universe works.
This is the promise of AtLAST, the Atacama Large Aperture Submillimeter Telescope, a European-led project now in design phase until 2028. The telescope would operate at submillimeter wavelengths—radiation between radio waves and infrared—the only way to see through cosmic dust. "We are missing the regions of space that are most obscured by dust," said Claudia Cicone, an astrophysicist at the University of Oslo and one of the project's leads. "Without a submillimeter, we're getting a very biased picture of what's out there."
Existing facilities like the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have pioneered this work, but ALMA functions like a microscope: its 66 antennas can only observe an area thousands of times smaller than the moon's surface in any given observation. AtLAST would flip the metaphor entirely, operating as a wide-angle camera. "AtLAST will image an area up to 16 moons in size with every observation, so we can map the hell out of the universe," said Tony Mroczkowski, an astronomer at the Institute of Space Sciences in Spain and another of the telescope's leads. This shift from detailed close-ups to sweeping sky surveys would allow astronomers to answer a fundamental question: where exactly is all the gas and dust in the universe?
The physical engineering is staggering. The primary dish alone would weigh approximately 4,400 tonnes—aluminum panels mounted on a massive steel backing structure—with a secondary 12-meter mirror, itself larger than most operational telescopes, helping to deliver its expansive field of view. The structure would be located near ALMA at over 5 kilometers above sea level, where the thin, dry atmosphere provides pristine viewing conditions.
What sets AtLAST apart is its commitment to sustainability at a scale rarely attempted in astronomy. The telescope would be entirely powered by renewable energies, combining solar power, battery storage, metal hydride energy storage, and a novel hybrid system that recovers kinetic energy as the telescope slows after moving—analogous to regenerative braking in hybrid vehicles. The project is also planning to use near-zero carbon methods to produce the steel and aluminum itself. As Cicone explained, "The telescope would be entirely powered by renewable energies, using a novel, tailored hybrid energy regeneration."
The vision reflects an emerging ethos in big science: ambition paired with climate responsibility. Researchers from eight countries beyond Europe—including Chile, South Africa, Canada, Taiwan, Thailand, New Zealand, Japan, and the United States—are collaborating on the design work through AtLAST2, refining prototypes of key technologies and planning for sustainable operation. The hope is that this project becomes a model for how large observatories can pursue transformative science without compromising the planet. AtLAST is designed to slot into a new generation of giant observatories set to reshape astronomy in the 2040s, following Europe's Extremely Large Telescope, which is nearing completion in Chile. Without a facility like this, astronomers warn, there will be a critical gap in humanity's ability to map the cold, dust-laden universe.