Astronomers warn Chilean hydrogen project could threaten one of Earth’s darkest skies

Space Exploration reported on a letter from a group of astronomers who said a planned hydrogen plant in Chile could affect research at major observatories.

The letter was led by Nobel Prize winner Reinhard Genzel and signed by 28 other astronomers. It asked the Chilean government to reconsider the planned location of the INNA hydrogen plant near Cerro Paranal in the Atacama Desert.

This site was home to major instruments, including the Very Large Telescope and the Extremely Large Telescope, which was still under construction.

The astronomers said the project could raise light levels in the sky and change how the observatories worked. The letter included the line,

“As currently conceived, the project represents an imminent threat to some of the most advanced astronomical facilities on Earth.”

The group referred to an analysis by the European Southern Observatory, which showed that the plant could raise light pollution and cause small ground movements. These changes could affect how well the telescopes gather data.

They also said the issues could not be fixed if the plant remained in its planned location. The plant’s developer had said its impact would be small. At the time of the report, Chilean authorities had not made a final decision.

Concerns about sky brightness and telescope use

The astronomers referred to a study by the European Southern Observatory. The report showed that the INNA project could raise sky brightness above Cerro Paranal by up to 35 percent. One quote stated,

“INNA would cause an increase of up to 35% in light pollution above Cerro Paranal.”

Another part of the report said the Cherenkov Telescope Array could see a brightness increase of up to 50 percent because it was closer to the proposed site.

The group also explained how brighter skies could affect current and future instruments. Xavier Barcons, the ESO Director General, said,

“We might lose the ability to observe about 30% of the faintest galaxies.”

He also said studies of exoplanet atmospheres could become harder if the sky became brighter. The Extremely Large Telescope, which was still being built, could also lose some of its power to observe distant objects.

The astronomers said the hydrogen plant could create small ground movements. Even slight shifts could affect how well telescopes tracked objects. The report also noted turbulence from the plant, which could change how clear the images were. The telescopes relied on stable air and low light to collect information about stars, planets, and distant galaxies.

Location issues and request for relocation

The letter said the main issue was the planned location of the plant. The site was only a few miles from Cerro Paranal. The astronomers said distance was important because the observatories depended on low light and stable ground and air. The group wrote,

“The proximity and extent of the infrastructure associated with the INNA project pose a grave threat, which cannot be mitigated.”

They argued that moving the project farther away would reduce these effects.

The INNA plant was a large renewable energy plant that included solar farms, wind farms, battery storage, and hydrogen production facilities.

The company behind the project, AES, said its impact on the sky would be small. But the astronomers said the data did not support that view. They stated that scientific research and energy development could exist together if the site were changed.

The letter noted that the Atacama region held major global astronomy sites. It included the Very Large Telescope, the Cherenkov Telescope Array, and the site of the Extremely Large Telescope.

These tools were used to study black holes, galaxy growth, and planets around other stars. The group said relocation would protect long-term research and the conditions needed for future discoveries.
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