Observing Samba and Tango’s reentries

For the final two spacecraft of ESA's Cluster mission, Samba and Tango, the journey ends with targeted reentries into Earth's atmosphere on 31 August and 1 September respectively. The reentries conclude a mission that has significantly advanced our understanding of Earth's magnetic environment, and they present a rare chance to observe a spacecraft breakup from an aircraft. Exactly how a spacecraft disintegrates during reentry remains unclear—extreme temperatures cause materials to melt and vaporise, and the vehicle breaks apart—and better understanding is needed to design spacecraft that fully burn up, reducing risk on the ground and preventing atmospheric pollution.

To gather this data, ESA is repeating an airborne observation experiment first performed during the reentry of Cluster's Salsa spacecraft in 2024. The ROSIE campaign, led by Astros Solutions, will fly from Tonga on 31 August to observe Samba's reentry, then return to Tonga and repeat the flight the next day for Tango. The Cluster satellites have been set on targeted reentry trajectories, ensuring they come down over a remote area of the South Pacific Ocean that is reachable by a small plane. Unlike most satellites, these spacecraft are not reentering due to atmospheric drag; their highly elliptical orbit is influenced by long-term gravitational interactions with the Earth, Sun and Moon, allowing precise planning of when and where they will reenter.

The observation team will collect as much reentry data as possible while the two spacecraft enter the atmosphere roughly 24 hours apart. The operation presents a significant logistical challenge: the plane must be at exactly the right location and time, oriented correctly, and positioned safely at the edge of the no-fly zone. The data gathered will inform future spacecraft design to ensure safer, more complete burn-up during reentry.