science<\/p>\n
Two-year mission bows out after 26 thanks to some heroic engineering<\/p>\n
The European Space Agency’s Cluster quartet is preparing for its final bow after Samba reentered Earth’s atmosphere, with Tango due to follow tonight.<\/p>\n
Samba lost contact at 21:26 UTC on August 31 and reentered at 21:39:38 UTC. Tango is expected<\/a> to follow at 21:30:31 UTC tonight. The other two satellites, Rumba and Salsa, reentered in 2025 and 2024, respectively.<\/p>\n The final reentries close the book on a prodigiously long-lived quartet that exceeded even optimistic expectations, thanks in no small part to the ingenuity of engineers on the ground. <\/p>\n Cluster II launched in 2000 aboard two Soyuz rockets from the Baikonur Cosmodrome. It replaced the original quartet, which was destroyed during the maiden flight of Ariane 5 in 1996, drawing on spare hardware and work already completed for the doomed spacecraft. <\/p>\n The four satellites were launched on a two-year mission to study the structure of Earth’s magnetosphere in three dimensions. The spacecraft were designed to last for five years, and their mission was repeatedly extended. Why terminate a set of functional spacecraft when the science data is still rolling in?<\/p>\n After about a decade, however, the batteries that powered the spacecraft while they passed through Earth’s shadow failed. From an engineering perspective, each satellite effectively died whenever it entered an eclipse.<\/p>\n “The first time it happened, this was a rather uncontrolled shutdown… the spacecraft were not designed to be switched off,” recalled spacecraft operations manager Bruno Sousa in a 2020 interview<\/a> with The Register.<\/p>\n And yet the spacecraft survived and restarted. Engineers devised a workaround to bring the spacecraft back to life in a controlled fashion. More hardware failures occurred, and again, engineers devised ways to keep the mission going.<\/p>\n