Astronomers calculate the growing carbon footprint of space science

For generations, astronomers have spent lonely evenings in remote mountaintop observatories, gazing at stars and planets as they whirl overhead. Today’s astronomy, however, is carried out on a grander scale: Massive arrays of receivers constantly feed signals to energy-guzzling supercomputers, and it takes years to build billion-dollar spacecraft and tons of rocket fuel to launch. Next-generation ground-based observatories will be huge, such as the Extremely Large Telescope, which will eclipse the size of the Colosseum in Rome when completed in 2024.

Now some researchers are reflecting on the carbon footprint of modern astronomy and realizing that, like everyone else, they need to consider alternative ways of doing business to control climate-warming emissions. That could include switching to solar power, which makes sense for observatories in Australia or Chile, where the skies are clear and lots of sunshine. Or it could mean finding other ways to save energy.

“We’re at the point where we need to do science on an industrial scale,” said Adriaan Schutte, program manager for the Square Kilometer Array, a linked system of two radio telescopes under construction in South Africa and Australia, which will collectively control the several thousand individual receivers. “If you want to discover something, you don’t just do it with your telescope in the backyard,” says Schutte. “We use energy on an industrial scale and you need to plan ahead for your increased CO2 emissions.”

Today in the journal Nature Astronomy, a group of European astronomers published an estimate of the global carbon footprint of all modern astronomy, including ground and space observatories. They calculate that the energy used to build and maintain the existing infrastructure is equivalent to 1.2 million tons of carbon dioxide per year and a total lifespan of 20.3 million tons. That larger figure equates to annual emissions from five coal-fired power plants, according to the Environmental Protection Agency’s Greenhouse Gas Equivalencies Calculator.

NASA’s new $9.8 billion James Webb Space Telescope, which launched in December and will return its first images to Earth this summer, will have a carbon footprint of 300,000 tons of CO2, according to the new study. That’s equivalent to burning 1,655 railroad cars of coal, using the same EPA calculator. The Very Large Telescope, which is located in Paranal, Chile, has an estimated carbon footprint of 540,000 tons of CO2 over its 21-year lifespan, the study reported.

Some may wonder why astronomers should be concerned about the size of their carbon footprint when other industries fare much worse. Annie Hughes, a co-author of the paper and a staff astronomer at France’s Institut de Recherche de Astrophysique et Planétologie (IRAP), says it’s important for scientists to lead by example. “Humanity is facing a climate emergency,” Hughes said during a press conference on March 17. “The scientific evidence is unequivocal that human activities are responsible for changing the Earth’s climate. And the scientific evidence is equally clear that we need to fundamentally change our activities in the next decade. So faced with such urgency, I and The authors of this article believe that everyone must act now to reduce their personal and professional carbon emissions, and this includes astronomers, like everyone else.”

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