A European observation satellite is hurtling towards Earth, and is expected to make landfall on Wednesday, after nearly 30 years in space.
The ERS-2 satellite will break up into pieces during re-entry, the majority of which will burn up, the European Space Agency (ESA) said.
Esa is still monitoring its landfall, which is predicted to occur somewhere over the east coast of central Africa.
The satellite was launched in 1995, following on from its sister satellite, ERS-1, which had been launched four years earlier.
At the time, they were both the most sophisticated Earth observation satellites ever developed.
In 2011, Esa retired ERS-2 and began the process of deorbiting.
After 13 years of it breaking down in orbit, mainly driven by solar activity, the satellite will naturally re-enter Earth’s atmosphere at around 3.49pm on Wednesday.
However, Esa’s Space Debris Office warned its prediction may be out by around one hour and 45 minutes before or after that time thanks to the influence of unpredictable solar activity.
This activity affects the density of Earth’s atmosphere and, therefore, the drag experienced by the satellite.
Dr James Blake, research fellow at the Centre for Space Domain Awareness, University of Warwick, said: “There are now thousands of active and defunct satellites orbiting the Earth and ERS-2 is the latest to undertake the return leg of its journey as it re-enters the Earth’s atmosphere.
“This is a fate that awaits uncontrolled satellites and debris that can no longer counteract the drag forces exerted by the Earth’s atmosphere – indeed, operators are encouraged to speed up the re-entry of their defunct satellites to keep space clear for future missions.
“Atmospheric drag is highly influenced by solar activity – ‘weather’ from the Sun that affects conditions in the near-Earth environment, where the satellites orbit.
“This is still very unpredictable, and so it’s a huge challenge to predict when and where a satellite will re-enter.
“Imagery from other satellites in space – such as those from HEO here – can supplement observations taken with ground-based sensors to help paint a clearer picture, and it’s exciting to see this technology advance.”
Any pieces of the satellite that survive making landfall will be spread out over a ground track on average hundreds of kilometres long and a few tens of kilometres wide, so the associated risks are deemed very low.
The re-entry is happening without human control, so it is impossible to say exactly when and where it will happen, but as the satellite gets closer to Earth, Esa can say with greater accuracy what will happen.
Throughout its working life, ERS-2 returned a wealth of information that revolutionised our perspective of Earth and understanding of climate change.
It collected data on Earth’s diminishing polar ice, changing land surfaces, rising sea levels, warming oceans, and atmospheric chemistry.
In addition, the ERS-2 was called upon to monitor natural disasters, such as severe floods and earthquakes, in remote parts of the world.