It has been floating above our planet for almost 30 years.
But a European Space Agency (ESA) satellite will finally crash back into Earth this week.
Launched from French Guiana in 1995, ERS-2 weighs just over 2,000kg – about the same as an adult rhino.
ESA estimates it will enter Earth’s atmosphere on Wednesday (February 21) at 11:14 GMT (12:14 CET).
Although experts have no idea where it will land, ESA says the annual risk of a human being even injured by space debris is about one in 100 billion.
Artistic illustration of the European Remote Sensing 2 (ERS-2) satellite in space. It is finally returning to Earth after ending its activities more than a decade ago
Image of ERS-2 captured from space by HEO, an Australian company with an office in Britain, taken by other satellites between January 14 and February 3. It shows ERS-2 as it rotates on its journey back to Earth. The British agency says they have been shared with ESA to help track the return of ERS-2
ESA said there is a degree of uncertainty in its 3 p.m. return forecast.
This means it could re-enter on Wednesday 3pm either side of 11:14 GMT – although 11:14 GMT is the agency’s best estimate.
“This uncertainty is mainly due to the influence of unpredictable solar activity, which affects the density of the Earth’s atmosphere and thus the drag experienced by the satellite,” the report said in a statement.
ESA said it is monitoring the satellite “very closely”, along with international partners, and providing regular updates on a special web page.
The ERS-2 satellite was launched on April 21, 1995 from ESA’s Guyana Space Center near Kourou, French Guiana, to study Earth’s land surfaces, oceans and polar caps.
After fifteen years, the spacecraft was still functioning when ESA declared the mission complete in 2011.
After the deorbitation maneuvers used up the satellite’s remaining fuel, ground control experts began lowering the altitude from about 785 km to 573 km.
At the time, experts wanted to minimize the risk of collisions with other satellites or increase the cloud of “space junk” currently orbiting our planet.
Since then, ERS-2 has been in a period of ‘orbital decay’, meaning it is gradually getting closer and closer to Earth as it orbits the planet.
ERS-2 satellite before launch. ERS-2 was launched in 1995, succeeding its sister, the first European Remote Sensing satellite ERS-1, which was launched in 1991. The two satellites were designed as identical twins with one key difference: ERS-2 included an additional instrument to monitor ozone levels in the atmosphere
The ERS-2 satellite was launched in April 1995 from ESA’s Guyana Space Center near Kourou, French Guiana (pictured)
ERS-2 will re-enter Earth’s atmosphere and burn up once its altitude decreases to about 50 miles (80 km) – about a fifth of the distance of the International Space Station.
At this altitude it will break into fragments, the vast majority of which will burn up in the atmosphere.
However, some fragments could reach the Earth’s surface, where they will “most likely fall into the ocean,” according to ESA.
“None of these fragments will contain toxic or radioactive materials,” the agency said.
While ESA cannot guarantee that there is no chance of ERS-2 hitting anyone, ESA has indicated that the annual risk of even one human being injured by space debris is less than one in 100 billion.
That is about 1.5 million times lower than the risk of dying at home in an accident and 65,000 times lower than the risk of being struck by lightning.
Worryingly, ESA describes the event as a ‘natural’ reentry, as ground crews cannot control the event during descent.
“ERS-2 consumed the last of its fuel in 2011 to minimize the risk of a catastrophic explosion that could have created a large amount of space debris,” the agency said.
‘The batteries were dead and the communications antenna and electronics on board were disabled.
Illustrated timeline of the European Remote Sensing 2 (ERS-2) satellite’s mission provided by the ESA, which estimates it will enter Earth’s atmosphere on Wednesday (21 February) at 11:14 GMT (12:14 CET) intrude
This was the last image of ERS-2 captured over Rome, Italy on July 4, 2011. Shortly afterwards, maneuvers began to deorbit the veteran satellite. Flight operations ended on September 5, 2011
“There is no longer a way to actively control the movement of the satellite from the ground during its descent.”
ERS-2 was launched in 1995 as a follow-up to its sister satellite, ERS-1, which had been launched four years earlier.
Both satellites were equipped with the latest high-tech instruments, including a radar altimeter (which sends pulses of radio waves to the ground) and powerful sensors to measure ocean surface temperatures and offshore winds.
ERS-2 had an additional sensor to measure the ozone content of our planet’s atmosphere, which is important for blocking radiation from the sun.
ERS-1 is no longer operational due to a malfunction in 2000, but its exact location is unknown.