The environmental toll of astronomy is surprisingly high

IIt’s hard not to love the Kepler space telescope. Launched in 2009, the venerable spacecraft has discovered nearly 5,000 suspected or confirmed exoplanets – or worlds orbiting other stars – during its 11-year lifespan. Built and launched at a relatively bargain price of $600 million, it has generated 4,306 scientific papers by 9,606 authors. So it’s all good, right? Well, not entirely.

In those same 11 years, the telescope that has discovered so many other worlds has done ours a disservice, generating an annual total of 4,784 tonnes of carbon dioxide emissions, or 52,620 tonnes during its life, mainly due to the electricity and supercomputing power it took to run it. This also amounts to 12 tonnes of CO2 per article and five tonnes per author.

Astronomy, in some respects, seems to be the purest of sciences. After all, it costs nothing to look up at the sky. But observatories on the ground and in space are taking a huge environmental toll – in terms of construction, launch, production and energy consumption, and even, at least before the pandemic, in the air miles burned as the roughly 30,000 world astronomers flew from conference to conference around the world.

Now a new paper in natural astronomy took full measure of the greenhouse gas footprint of the skygazing discipline. For the study, the researchers analyzed the total CO2 output from 46 space missions and 39 ground-based observatories, dating as far back as the 62-year-old Observatoire de Haute Provence in southeastern France. and as recently as the new InSight observatory in New Mexico, which went online in 2017. At that time, the researchers, affiliated with the Institute for Research in Astrophysics and Planetology (IRAP), in Toulouse, France, have concluded that the 85 observatories had generated a prodigious 20.3 million tonnes of CO2, or an average of 1.2 million tonnes per year.

“Astronomers are caught up in the day-to-day – the next funding grant, the next new project,” Annie Hughes, IRAP astronomer and co-author of the paper, said at a March 17 press conference. announcing the results. “Our colleagues are aware that climate change is a problem, but there is a huge amount of inertia in the system.”

The paper, which the researchers had been working on for three years, used 2019 as the base year for data and therefore did not include new observatories such as the James Webb Space Telescope or the massive square kilometer array currently under construction in Australia. and South Africa. Other spacecraft not included in the work include the trio of ships from China, the United States and the United Arab Emirates that arrived on Mars in 2021. But even without these new field entries, the numbers are quite troubling. .

For ground-based observatories, simple construction activity dominates the first phase of CO2 emissions – with the pouring of concrete, which releases 600 kg (1,100 lb) of CO2 for every tonne of material used. The cement industry alone is responsible for 8% of annual greenhouse gas emissions.

“VLT [Very Large Telescope] and ALMA [Atacama Large Millimeter/submillimeter Array] are simply extremely large and expensive infrastructures and they have a huge carbon footprint,” IRAP astronomer and paper co-author Jürgen Knödlseder said at the press conference.

Location also makes a difference. Once a ground-based telescope is built, its greatest CO2 contribution comes from the electricity needed to perform its observations. Chile’s Atacama Desert is not only home to the VLT and ALMA, but also 14 other observatories, thanks to its extremely dry air and 330 nights of clear skies per year. This makes for great viewing, but Chile only ranks in the middle of countries when it comes to the cleanliness of its power grid.

“Chile has a sort of average emission factor for electricity,” Knödlseder said. “So it’s not as high as, say, Australia, which burns a lot of coal, but it’s not as low as Sweden and France, which use a lot of renewable energy.”

Worse still, extremely remote observatories may not even be connected to their home country’s power grids and therefore must run on their own diesel-generated electricity. ALMA, one of these observatories, emitted almost 300,000 tons of CO2 during its construction phase and continues to pump an average of 56,154 tons per year.

Space observatories have, overall, a lower carbon footprint because they are extremely small compared to terrestrial observatories and their construction usually takes place in clean rooms and air-conditioned hangars. Their biggest impact on the climate comes from the electricity used in their annual operation, which adds up over time. The Hubble Space Telescope, which is still operating and had been in service for nearly 30 years according to 2019 data used in the article, emitted 1.2 million tonnes of CO2 over its lifetime, or about 21 tons for each of the 52,497 items. that have been written about his findings. The James Webb Space Telescope, launched on Christmas Day 2021, could have a similar carbon footprint of more than 1.22 million tonnes of CO2 over its projected 20-year lifespan, the authors estimate.

The document emphasizes that the astronomical community must take drastic steps to reduce its carbon footprint and not just view it as the cost of doing business. The 20.3 million tons of CO2 emitted in total by the 85 observatories represent after all the equivalent of the annual production of greenhouse gases of entire countries such as Croatia, Bulgaria or Estonia. There are ways to reduce these numbers.

“The first step,” said Lyigi Tibaldo, IRAP astronomer and co-author, “is for existing structures to be decarbonized, switching to renewable energy sources.” The sun is abundant in the Atacama, making solar power a viable option. And the more the global energy network, especially in Europe, depends on renewable energy, the more the telescopes there will be able to operate without too much of a greenhouse effect. Most space observatories already rely on solar panels to operate, but a cleaner grid means their observations can be made and their data analyzed with a lower carbon footprint too.

Another response, the authors say, is to slow the current boom in building new observatories in the Atacama and elsewhere, relying more on the astronomical infrastructure that already exists. “The steep emissions reduction required over the next decade will not be achieved if we continue to build new infrastructure at the current rate,” Tibaldo said. “It will also give us more time to do a more comprehensive exploration of the data we have from the existing infrastructure.”

This, the authors acknowledge, will not be a popular prescription. “Some of our colleagues are a little shocked at the idea of ​​slowing down,” Knödlseder said. “But the [climate] the urgency we face is so great that we believe this option must indeed be on the table.

For now, telescopes will continue to operate and astronomers will continue to observe and paper will continue to be produced by the thousands and, at least academically, that is a very good thing. But as the authors noted in the very first paragraph of their article, United Nations Secretary-General António Guterres warned that the latest report from the Intergovernmental Panel on Climate Change (IPCC) does not is nothing less than “code red for humanity”. It’s all well and good to seek out and study new worlds. But it is even more important that we preserve and protect what we have.

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Write to Jeffrey Kluger at [email protected]


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