A groundbreaking demonstration by the European Space Agency (ESA) suggests it’s possible to deorbit satellites safely and in a reasonably controlled manner, even for those not originally designed for such maneuvers.
As planned, the Aeolus Earth Explorer satellite met its demise above Antarctica on July 28 at around 3:00 p.m. ET, as U.S. Space Command confirmed shortly afterward. The reentry followed a series of complex maneuvers that lowered the defunct satellite’s orbit from approximately 199 miles (320 kilometers) to a mere 75 miles (120 km), ensuring its safe return and eventual incineration in the atmosphere.
A newly released animation illustrates the possible final moments of the spacecraft. The simulation, made with the SCARAB tool, is based on a model of the Aeolus spacecraft that took the satellite’s shape, size, mass, and materials into consideration, along with the principles of aerothermodynamics. The simulation depicts Aeolus’s reentry in its final moments, showcasing the controlled descent made possible by its “six degrees of freedom,” that is, its ability to move freely in three-dimensional space along the x-, y-, and z-axis.
Importantly, the satellite wasn’t designed to fly at such low altitudes, but the demonstration showed that it’s still possible to deorbit satellites in this particular manner—at least for a similar cohort of satellites with sufficient amounts of fuel remaining.
Aeolus, designed and operated by the European Space Agency (ESA), studied global wind patterns prior to its retirement, contributing to our understanding of Earth’s atmosphere and enabling more accurate weather predictions. But the satellite had been losing altitude at a steady pace and it was nearly out of fuel. Without intervention, it would continue its uncontrolled descent and eventually burn up in Earth’s atmosphere, with debris falling unpredictably in undesignated locations.
To prevent potential risks to people and property below, ESA decided to deliberately crash the satellite into Earth’s atmosphere, but in a controlled manner. For an entire week, mission controllers guided the satellite to its doom, allowing most of it to burn up during reentry. “This assisted reentry attempt goes above and beyond safety regulations for the mission, which was planned and designed in the late 1990s,” Tim Flohrer, head of ESA’s Space Debris Office, explained in a statement.
For the assisted reentry, teams of engineers and flight dynamics experts positioned Aeolus such that any remaining fragments would fall safely within the satellite’s planned Atlantic ground tracks. By successfully executing the controlled reentry, the risk of potential debris falling in populated or undesired locations was significantly reduced. “By turning Aeolus’s original fate—an uncontrolled, ‘natural’ reentry—into an assisted one, they reduced that risk another 42 times.”
This bodes well for similar future efforts, in the ongoing effort to keep low Earth orbit free from all that superfluous clutter.