Cluster’s final reentry strengthens data for safer, more sustainable satellite design

The Cluster mission danced its final dance as Tango reentered the atmosphere Sept. 1 at 11:30:31 p.m. CEST. The end of the Cluster mission in 2024 marked the start of the reentry data-collection campaign. After four targeted reentries, this is now a proven method of safe end-of-life disposal. It also enabled repeated observation of the reentries by a plane full of scientists, creating a unique reentry data set that will improve our understanding of the destructive process and inform the design of safer, more sustainable satellites in the future.

Ready to Tango

The ROSIE airborne observation team was able to observe both the Samba and Tango reentries with 29 of the 30 instruments on board its plane. Each experiment built on lessons learned from the previous ones, fine-tuning the instruments and cameras while the team back home improved the accuracy of the reentry prediction and resulting flight path.

For Tango, even the plane’s pilot supported this optimization by banking the plane at just the right moment to let the team keep the burning spacecraft streaking across the sky in their field of vision for a few more seconds. The scientists observed Samba and Tango for an average of about 50 seconds, tracking them across the sky.

Saying final goodbyes to Cluster

Shortly before Tango’s reentry, many members of the flight control, mission and reentry teams were able to send a final command to Tango, each saying goodbye, until it was time for the spacecraft to reenter. About a quarter-hour before reentry, its signal via the Kourou ground station, which sent telemetry until the end, was lost forever.

After 26 years, Cluster mission operations had come to an end, a milestone for the many people who dedicated significant parts of their lives to the mission, which greatly improved our understanding of Earth’s magnetosphere.

“This is a time when you realize that once you build something like the Cluster mission, you imbue it with a soul. The team has created something beautiful. We have seen its final act, but it is clear that the soul of the Cluster family will be around for plenty of time to come,” says Philippe Escoubet, Cluster mission manager at ESA.

Next up, Draco: reentry observations from the inside

The next goal for ESA’s reentry specialists is to witness a reentry from the inside and see exactly what happens, how, when and where, with the Draco reentry mission.

Draco is scheduled for launch in 2027 for the purpose of going through a fiery reentry while recording exactly what happens to the satellite. With more than 200 sensors, four cameras and an indestructible capsule to keep the collected data safe, Draco will offer a unique inside perspective on the destructive process.

“To top it off, our reentry scientists will be ready to board a plane once more to witness the event from below. With three practice runs under their belt, the team will be able to link observations made from the plane to what’s happening within Draco at exactly that time,” says Stijn Lemmens, acting head of space debris.

“With the data from the Cluster and Draco reentries, we will improve reentry models. This will help us better predict where objects will fall and how they affect the atmosphere, and build better satellites to further reduce the chance that any pieces will reach the ground and pose risks to people or infrastructure.”

Who’s behind this story?

Swati Mestri

Swati Mestri holds a bachelor’s degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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