Later this month, a dead European satellite will do a fiery death plunge that its controllers will closely watch. The satellite will crash back to Earth.
The spacecraft that is being sent is the European Remote Sensing 2 (ERS-2) satellite, which was launched by the European Space Agency (ESA) in April 1995 and completed its Earth observation mission in September 2011.
Even before ERS-2’s main mission concluded, ESA started preparing for its retirement by carrying out 66 engine burns in July and August of 2011. The actions “used up the satellite’s remaining fuel and lowered its average altitude from 785 km [488 miles] to about 573 km [356 miles] in order to greatly reduce the risk of collision with other satellites or space debris and to ensure the satellite’s orbit would decay fast enough for it to reenter Earth’s atmosphere within the next 15 years,” the European Space Agency (ESA) stated in a FAQ regarding the return to Earth.
According to the FAQ, ERS-2 “was the most sophisticated Earth-observation spacecraft ever developed and launched by Europe.” It weighed 5,547 pounds (2,516 kilograms) at the moment of liftoff. It now weighs roughly 5,057 pounds (2,294 kg) without gasoline.
Although that seems rather substantial, ERS-2 is by no means an anomaly in space debris; according to ESA authorities, items with comparable mass typically reenter Earth’s atmosphere every week or two.
Furthermore, far bigger objects have recently crashed back to Earth. For instance, China’s Long March 5B rocket’s 23-ton core stage, which has angered NASA officials and others in the space community, falls down uncontrollably a week or so after each liftoff.
In the last three years, there have been three instances of these striking reappearances; in April 2021, July 2022, and October 2022, the three modules for China’s Tiangong space station were launched by Long March 5B vehicles.
The decline of ERS-2 has been substantially longer-lasting, spanning the previous 13 years. However, the satellite is already low enough to experience a very rapid descent due to atmospheric drag, and this process will only quicken in the upcoming days. (This fall is uncontrollable; ERS-2 can’t execute any more engine burns since it runs out of fuel.)
When and where ERS-2 will strike the majority of Earth’s atmosphere is yet unknown. However, since water makes up almost 70% of our planet’s surface, there’s a significant probability it will return over an ocean.
The FAQ states that the satellite will disintegrate after it reaches an altitude of roughly 50 miles (80 km). The majority of the resultant pieces will subsequently catch fire in the atmosphere. According to the ESA, you shouldn’t be overly concerned about the ones that reach the surface because they won’t contain any radioactive or harmful materials.
And it would take a lot of bad luck to be struck by one of them, or by any space debris, for that matter.
ESA officials stated in the FAQ that “the annual risk of an individual human being injured by space debris is under 1 in 100 billion.” That’s about 65, 000 times less likely than getting struck by lightning.