The ozone layer is an invisible shield that protects us from the sun’s harmful rays. But the instruments that help monitor its condition will soon cease to work. Two satellites – NASA’s Aura and the Canadian Space Agency’s SCISAT – have been collecting important data on ozone-depleting substances for more than 20 years. Unfortunately, their missions are coming to an end, and without replacements, we may be left in the dark about what’s threatening the atmosphere.
Photo: NASA
Launched in 2003 and 2004, Aura and SCISAT measure gases that harm the ozone layer – chlorine compounds and nitrogen oxides, for example – every day. Many of these are released into the atmosphere because of old chemicals that mankind used to use before they were banned in 1989 under the Montreal Protocol. These satellites have helped to learn how such substances affect the sky, and have even shown that smoke from huge forest fires in Australia in 2019-2020 has destroyed some of the ozone.
By mid-2026, the Aura satellite’s batteries will stop working because its solar panels will run out of power. SCISAT will probably last a little longer, but it has already far exceeded its lifetime. When they shut down, scientists will no longer be able to monitor dangerous gases or study how wildfires and new technologies – like particle spraying to cool the climate – affect ozone.
“It’s like if a doctor’s precision instruments were taken away and he was left with a simple X-ray,” says Ross Salauitch, a scientist at the University of Maryland. – We’ll see that there’s something wrong with the ozone, but we won’t know what’s causing it.” While other instruments will continue to measure the ozone layer itself, without Aura and SCISAT we won’t know what substances are destroying it. That’s scary, because ozone over the northern hemisphere is recovering slower than hoped, and old satellites falling down can release new harmful chemicals.
There is hope for new satellites from NASA and the European Space Agency, but they haven’t been approved yet.
