An uncontrolled satellite re-entered the Earth’s atmosphere somewhere between Alaska and Hawaii on Wednesday, astronomers confirmed.
The pioneering European satellite, known as ERS-2, entered the atmosphere at 17.16pm on Wednesday after almost 30 years in orbit, the European Space Agency said. It is thought to have broken into pieces, with the majority burning up and the remains plummeting into the ocean below.
When it was launched in 1995, ERS-2 “was the most sophisticated Earth-observation spacecraft ever developed and launched by Europe”, according to the Esa, and revolutionised our understanding of the climate crisis.
“It provided us with new insights on our planet, the chemistry of our atmosphere, the behaviour of our oceans and the effects of humankind’s activity on our environment,” said Mirko Albani, the head of the Esa’s heritage space programme.
The satellite was retired in 2011 and the Esa decided to “de-orbit” it to reduce the chance of a collision with another probe.
Photos of the satellite plummeting towards the atmosphere were released by the Esa on Monday. The images were taken between 14 January and 3 February, when ERS-2 was still at an altitude of more than 300km (186 miles).
The satellite was approaching Earth at more than 10km (6 miles) a day, with the speed of its descent increasing rapidly in the final hours. When it reached around 80km, it is assumed to have started to break and then burn up. The exact timing was difficult to predict due to unpredictable atmospheric conditions, which can increase or decrease drag on the satellite, and the probe’s tumbling motion.
The vast majority of the satellite is likely to have burnt up and any pieces that survived are expected to be spread out somewhat randomly over an ocean expanse hundreds of kilometres long and tens of kilometres wide.
“The risks associated with satellite re-entries are very low,” the Esa said.
“It’s worth highlighting that none of the elements that might re-enter the atmosphere are radioactive or toxic,” said Albani.
Dr James Blake, from the Centre for Space Domain Awareness at the 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.”
