What if astronomy reduces its carbon footprint?

Greener space missions? Stargazing emits a significant amount of CO2, according to the controversial study, and in the face of the climate emergency, astronomers must reduce the carbon footprint of their research infrastructures.

For the first time, researchers have tried to estimate the amount of greenhouse gases produced by 30,000 astronomers and their working instruments, which are ground-based radio telescopes, probes and rovers sent into space.

The total activity of these instruments since they went live has produced at least 20.3 million tonnes of CO2, the equivalent of Estonia’s or Croatia’s annual carbon footprint, according to initial findings published Monday in the journal Nature Astronomy.

According to astronomical data, this would mean annual emissions of 1.2 million tons.

The study highlights that the number is almost “five times higher” than the amount generated by air travel by astronomers when they travel for professional reasons. “The astronomy community is currently discussing reducing the carbon footprint associated with transportation as well as supercomputing activity,” Jürgen Knodlseder, director of research at CNRS and lead author of the study, told AFP. “That’s good, except they don’t see an elephant in the room: a matter of infrastructure.”

To estimate the size of the “elephant”, the researcher went through 50 space missions and 40 ground-based observation devices: the Hubble and Max Planck telescopes, the Insight research missions (Mars), the Rosetta probe (Churi comet), the Very Large Telescope (VLT). ) in Chile…

– “Ivory Tower” –

Ideally, building materials, operating costs, electricity consumption should have been taken into account, but these data were often not available, sometimes due to a lack of transparency on the part of the space agencies, explains Jürgen Knödlseder, who works at the Institute for Research in Astrophysics and Planetology in Toulouse.

Computer image of the James Webb Telescope transmitted by Astrium on October 20, 2009 (HO/ASTRIUM/AFP/Archive – ASTRIUM)

To fill in these gaps, his team used a method developed by Ademe (Environmental and Energy Agency) and the Association for Carbon Balance (ABC): the so-called money ratio method, according to which the carbon emissions of an activity are proportional to its cost and mass.

Thus, by their calculations, the $10 billion James Webb Space Telescope and the upcoming Array of Square Kilometers giant radio telescope in South Africa and Australia alone would be responsible for the equivalent of at least 300,000 tons of CO2.

“We have to think about reducing greenhouse gas emissions in our infrastructure,” says Jürgen Knödlseder. And “everyone should contribute, including astronomers who are not in an ivory tower,” Annie Hughes of the Max Planck Institute, one of the study’s authors, commented during a press conference.

– “Slow down the car” –

“I know it might be shocking, but we have to slow down the machine if we want to cut emissions by almost 50% by 2030,” said fellow astronomer Luigi Tybaldo.

General view of one of the SKA telescopes in South Africa, in Carnarvon, July 2018 (AFP/Archive - MUJAHID SAFODIEN)
General view of one of the SKA telescopes in South Africa, in Carnarvon, July 2018 (AFP/Archive – MUJAHID SAFODIEN)

“Like any activity, astronomy has a significant carbon footprint, so our challenge is to slow down the construction of infrastructure while continuing the search for excellence,” said Eric Lagadec, president of the French Society for Astronomy and Science. participate in the study.

But the methodology is controversial: monetary valuation generates a high degree of uncertainty (up to 80%), which can “damage the reliability of the results,” writes Andrew Ross Wilson in a commentary published in the margins of the study.

“With no details on what the plant consumes, they calculated +at random+,” astrophysicist Françoise Combe from the Paris-PSL observatory is surprised for her part. Who also disputes the fact of dividing the total cost by the number of astronomers: “When you build an observatory, it’s for science, it benefits millions of people! It’s like dividing the cost of an opera only by those who go there,” the scientist comments.

“The method is debatable, but the approach is the first step that leads to reflection,” concludes Eric Lagadec.

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