The construction and operation of space missions, telescopes and other facilities produces more greenhouse-gas emissions than any other aspect of doing astronomy and cosmology research. That is according to a new study, which shows that if the field is to become more sustainable in future then the pace of building new observatories and space missions will need to be slower than it has been during the past few decades.

There has been an increased interest recently on the climate impact of scientific research. Much of the attention has focused on the effect of academic travel and other research activities such as the use of supercomputers. There has been less attention, however, on research infrastructure such as greenhouse-gas emissions from the construction and operation of space observatories, planetary probes and ground-based observatories.

To address this gap, astrophysicist Luigi Tibaldo from the Institut de Recherche en Astrophysique et Planétologie in France and colleagues estimated the greenhouse-gas emissions for nearly 50 space-based missions and 40 ground-based telescopes.

For ground-based facilities, the calculations assume that greenhouse-gas emissions are proportional to construction and operating costs, while for space and satellite missions, it is linked to the full mission cost and payload launch mass.

The team estimates that active astronomy research infrastructures worldwide will emit a combined total of more than 20 million tonnes of carbon dioxide equivalent (CO₂e) over their lifetimes – similar to the annual emissions of countries such as Estonia, Croatia and Bulgaria.

The strong reduction in emissions that is required in the next decade will not be achieved if we continue building new infrastructures at the pace that is occurring right now

Luigi Tibaldo

Annual emissions from research facilities are estimated to be around 1200 kilotonnes of CO₂e with around 520 ktCO₂e attributed to space missions and 760 ktCO₂e from ground-based observatories.

According to the researchers, this translates to 36 ktCO₂e per year per astronomer and makes research infrastructures the single largest contributor to the carbon footprint of an astronomer, being around five times larger than the environmental cost of travel.

The researchers say that if astronomers want to cut their carbon footprint, they should focus on reducing emissions from research infrastructures. “Solutions are clearly available, the first step that is needed is that the existing infrastructures are decarbonised, for example by switching to renewable energy power sources,” says Tibaldo. “One important step we recommend is that all the facilities carrying out astronomical research carry out more detailed analysis of their greenhouse gas emissions… and make their results public.”

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The team acknowledges that its emission estimates for individual facilities have an uncertainty of about 80% but says that other fields that are dependent on large research infrastructure will likely have a similar breakdown of emissions to astronomy.

Tibaldo warns that decisions that are made now on future research infrastructures will lock-in emissions from astrophysics research for decades to come. “We think that the strong reduction in emissions that is required in the next decade will not be achieved if we continue building new infrastructures at the pace that is occurring right now,” he adds.