Salsa’s final bow: European satellite set for a fiery return to Earth

A European satellite which UK scientists helped build is set to make a fiery return to Earth after spending nearly quarter of a century in space.

Salsa is the first of four European Space Agency (ESA) spacecraft to take a bow, with re-entry expected to take place on Sunday at around 1948 UK time.

Its return will mark the first-ever “targeted” re-entry for a satellite, the ESA said.

This means Salsa will fall at a specific time and place – in this case a sparsely populated region in the South Pacific – but will not be controlled as it re-enters the atmosphere.

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It is part of a satellite quartet called Cluster – which also includes Rumba, Samba and Tango – that blasted off 24 years ago to help scientists learn more about the mysteries of space weather.

Anne Chadwick, operations manager at RAL Space’s Joint Science Operations Centre (JSOC), which played a key role in keeping the satellites operational, said: “It’s bittersweet to see the beginning of the end for Cluster.

“Many of us at JSOC have spent decades working on the project, so it’s been a big part of our lives for a long time.”

The Cluster II mission was expected to last two years but managed to extend its life by more than two decades, providing valuable data that led to the publication of more than 3,200 scientific papers.

Professor Andrew Fazakerley, of the Mullard Space Science Laboratory at UCL, who was principal investigator of the Peace instruments on all four Cluster spacecraft over more than 20 years, said: “It will be sad to see the mission end, but it will leave a very impressive legacy, both in terms of papers already written, and also through a very high quality data archive that will be used to answer many more questions.”

JSOC, which hosts the UK Cluster Data Centre, led the development of the science data systems used worldwide.

But keeping the satellites operational came with numerous challenges, from performing tricky space manoeuvres and dealing with dying batteries to fixing unexpected IT bugs.

The mission has been helping scientists uncover the mysteries of the Earth’s powerful magnetic shield known as the magnetosphere, which protects the planet from the stream of charged particles emitted by the Sun known as the solar wind.

Interaction between the solar wind and the magnetosphere is what causes space weather, which can also sometimes produce the Northern Lights.

Space storms can interfere with radio communications and GPS signals, put orbiting satellites at risk, and – in extreme cases – damage power grids on Earth, so predicting when these occur could help governments and companies protect these critical systems.

Prof Fazakerley said: “Cluster is an incredibly successful mission which has contributed enormously to advances in our understanding of the Earth’s magnetosphere and its interaction with the solar wind.

“These advances are key to helping us better predict severe space weather and its impacts.”

The National Space Operations Centre (NSpOC), which is responsible for monitoring re-entry of space objects that might pose a risk to the UK or the UK Overseas Territories, will be tracking Salsa’s return.

The spacecraft has been orbiting in an elliptical path for the last three days but as it starts entering the atmosphere and reaches 62 miles above sea level, intense friction with particles in the atmosphere will cause it to heat up and disintegrate.

Angus Stewart, joint head of NSpOC, said: “We are monitoring the re-entry of ESA’s Salsa satellite and expect most of the object to burn up in the atmosphere with any remaining fragments assessed as likely to land in uninhabited areas.

“Overall, there is a very low risk to human life or property.

“By managing satellite re-entries responsibly, as is the case with this event, operators reduce space debris and make space safer for future missions.”

UK scientists, which also included a team from Imperial College London, were involved in the hardware development of the Cluster satellites.

Some of the researchers involved were principal investigators for three of the 11 instruments on board each of the four spacecraft.

Following Salsa’s re-entry, the three remaining satellites will enter “caretaker” mode, with operators monitoring them to minimise the risk of collision with other satellites or Earth itself.

Rumba is expected to return in November 2025 while Samba and Tango will bid their final goodbyes in August 2026.