
On Friday, a 1,360-pound European satellite named Aeolus made an unprecedented attempt to return to the Earth after it outlived its mission. Its time in orbit is up, and rather than let it drop naturally into the atmosphere at high speed — which could produce dangerous debris — the European Space Agency (ESA) attempted to guide the craft towards a remote part of the planet where it would unlikely cause damage.
The Aeolus mission was launched in 2018 to measure winds on Earth to improve weather forecasting and climate models. The spacecraft carried just one instrument, a Doppler wind lidar, which worked by measuring the movements of particles in the atmosphere as they moved across the surface of the Earth. The result is an accurate picture of the planet’s atmospheric structure. It can map winds on scales far more significant than anything available on the ground or by aircraft.
Aeolus was designed for just three years but surpassed expectations and operated for almost five. With the spacecraft running low on fuel, ESA is attempting to use what remains to bring it down safely.
Since June 19, Aeolus has been slowly dragged down from its operational altitude by gravity and the Earth’s atmosphere. But on Monday, mission controllers began a series of maneuvers to lower the satellite’s orbit by a few miles each day. As of Thursday, they had reduced Aeolus’ altitude to 174 miles, with officials aiming for the craft to be in an elliptical orbit 75 miles above Earth when it crashes into our planet’s atmosphere.
As the satellite falls, it will emit a bright flash, followed by vibrations. Scientists believe that just 20 percent of the satellite will make it through the atmosphere intact — most of the rest will burn up as it reaches Earth’s surface. But the ESA says it will still be a valuable opportunity to gather data on improving future spacecraft design.
ESA’s efforts to reduce risk by performing a controlled re-entry “sets a precedent for sustainable spaceflight and safe space debris management,” an agency spokesperson wrote in a blog post last month. The agency’s simulations have suggested that the spacecraft may survive the crash, although it will likely break into several pieces.
If you’re on a dual carriageway near Stevenage, England, and drive past a nondescript building that houses Airbus Defence and Space, you’d be forgiven for not realizing that sitting inside is a world-leading satellite that took over a decade to build. It’s called Aeolus, named after the Greek god of winds. The same name is also shared by the character of Aeolus in Homer’s Odyssey, who was a lover of Odysseus’s wife, Polymele. The same name was also shared by Aeolus’ son Aether, who was responsible for the strong winds that helped the legendary hero sail to Ithaca.