Salsa’s last dance: This European satellite will soon fall from space in an exciting re-entry
On September 8, 2024, a satellite called Salsa will re-enter the atmosphere and burn up. What makes this re-entry so special is that its operators have carefully guided it down from an altitude of 130,000 km to burn up safely over a hand-picked region of the South Pacific – if all goes according to plan.
Salsa will be the second satellite to end up in a planned and controlled “guided re-entry”, after which Re-entry of ESA’s weather satellite Aeolus last year. Such re-entries could help satellite operators prevent debris from either floating in orbit or unexpectedly and potentially populated areas.
Salsa is a member of a four-person group called Cluster. Salsa’s three companions are also named after dances: Rumba, Tango and Samba. The four identical satellites have been monitoring the Earth’s magnetic field since 2000. When Cluster was first launched, its mission was only supposed to last two years. But its satellites are still intact and sending back valuable scientific data almost a quarter of a century later. But Cluster’s days are now numbered.
If ESA had decommissioned Cluster in 2002 as planned, the four satellites might have been left to their fate. But the specter of rapidly accumulating space debris means that ESA wants to be more careful with its old spacecraft. “By studying how salsa burns up, which parts could survive, for how long and in what condition, we will learn a lot about how to build satellites without debris,” said Tim Flohrer, head of ESA’s Space Debris Office, in a opinion.
Controlling reentry not only ensures that old satellites do not pollute low Earth orbit, it also gives operators more precise control over where obsolete spacecraft crash-land.
It’s extremely unlikely that falling satellites will actually cause damage or injury – the space agency says you’re three times more likely to be hit by a meteorite than by a piece of satellite debris. But ESA wants to minimise this risk itself and is therefore trying out these new controlled re-entry methods.
Aeolus was the first test of ESA’s new method for controlled reentry missions. Over the course of several weeks, Aeolus operators carefully manoeuvred the satellite from its old orbit of 320 km altitude to 120 km, low enough to be pulled by the Earth’s atmosphere to a fiery end. The exercise was carefully designed to burn Aeolus up over the Atlantic Ocean.
What sets Salsa apart from Aeolus is its much more eccentric orbit, which varies from just 100 km altitude to over 130,000 km. In January, Salsa performed a maneuver that will bring its point of closest approach to just 80 km sometime this month. This will lead Salsa to its demise over a remote part of the South Pacific.
After Salsa’s re-entry, its three counterparts are set to meet a similarly fiery end. Rumba will re-enter the Earth’s atmosphere in 2025, followed by Tango and Samba in 2026. All four deaths are part of a major experiment – ESA hopes to observe identical spacecraft burning up at a different angle.
