The European Space Agency's final two Cluster spacecraft, Samba and Tango, will end their operational lives as they burn up in Earth's atmosphere on August 31 and September 1, respectively. The controlled reentries mark the conclusion of a mission that has significantly advanced understanding of Earth's magnetic environment. The event will provide a rare opportunity for scientific observations of spacecraft disintegration during reentry.
ESA plans to send an airborne observation team from Tonga to witness both reentries from below, repeating an experimental approach used during the reentry of Cluster's Salsa satellite in 2024. The ROSIE airborne observation campaign, led by Astros Solutions, will deploy 30 instruments to collect spectral, visual and infrared data as the satellites descend over the remote South Pacific Ocean roughly 24 hours apart. The timing and positioning require precise coordination to capture the data, with the aircraft needing to reach the exact location at the right moment while remaining safely outside restricted airspace.
Stijn Lemmens, senior space debris mitigation analyst at ESA, said understanding how spacecraft disintegrate during reentry is essential for designing future satellites that burn up completely in the atmosphere, reducing ground risk while minimizing atmospheric pollution. Previous observations of Salsa's reentry revealed unexpected findings, including a discrepancy of up to 20 percent between observed and expected atmospheric density and earlier-than-predicted structural breakup. Those results highlighted gaps in current models of reentry behavior.
The Cluster spacecraft differ from most orbiting satellites because their reentries are driven by long-term gravitational interactions with Earth, the Sun and Moon rather than atmospheric drag alone, allowing ESA to plan and target their descent locations precisely. In January, the operations team set the satellites on their final trajectories to ensure reentries would occur in accessible yet remote locations. Cluster's final two spacecraft remain in better power states than their predecessors, offering stronger prospects for collecting additional complementary data during reentry, provided they avoid experiencing reboots during descent.
ESA's reentry observation efforts directly support its Zero Debris approach, which seeks to ensure the sustainable use of space as the number of satellites in orbit increases and more missions reach operational end-of-life. Following Samba and Tango's reentries, ESA's Draco spacecraft will continue the observational program, recording its own reentry from aboard while being observed by scientists on a plane.
