A dead European satellite will return to Earth later this month in a deadly dive that will be carefully monitored by its handlers.
The next spacecraft is ESA's European Remote Sensing Satellite 2 (ERS-2), which was launched into Earth orbit in April 1995 and completed Earth observation missions in September 2011.
ESA began preparations for ERS-2's demise even before its primary mission ended, burning through 66 engines in July and August 2011. Those maneuvers exhausted the satellite's remaining fuel and lowered its average altitude from 785 kilometers. [488 miles] To about 573 km [356 miles] “In order to significantly reduce the risk of collisions with other satellites or space debris and to ensure that the satellite's orbit will decay quickly enough for it to be able to reenter the Earth's atmosphere within the next 15 years,” ESA officials wrote in common questions About coming back.
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ERS-2 was “the most advanced Earth observation spacecraft ever developed and launched by Europe,” according to the FAQ. At the time of takeoff, it weighed 5,547 pounds (2,516 kg). Now, without fuel, it weighs about 5,057 pounds (2,294 kg).
This is a pretty big deal, but ERS-2 is still far from being space junk; Objects of similar mass re-enter Earth's atmosphere every week or two on average, ESA officials wrote.
Much larger objects have crashed into Earth recently. For example, the 23-ton core stage of China's Long March 5B rocket falls out of control about a week or so after each launch, a design feature that has drawn the ire of NASA officials and others in the space community.
These dramatic comebacks have occurred three times in the past three years; The Long March 5B vehicles launched the three modules of China's Tiangong Space Station, in April 2021, July 2022, and October 2022.
The fall of ERS-2 has been much longer, occurring over the past 13 years. But the satellite is now low enough to be pulled down relatively quickly by atmospheric drag, and the process will only accelerate in the coming days. (This fall is uncontrollable; ERS-2 has run out of fuel and can therefore perform no more engine burns.)
It is too early to predict where and when ERS-2 will collide with the bulk of Earth's atmosphere. But chances are good that it will return to the ocean, where water covers about 70% of our planet's surface.
The satellite will disintegrate when it reaches an altitude of about 50 miles (80 km), according to the FAQ. Most of the resulting fragments will burn up in the atmosphere. Don't worry too much about the ones that reach the surface, because they won't contain toxic or radioactive materials, according to the European Space Agency.
And you'd have to be really unlucky if you got hit by one of them – or any piece of space junk, for that matter.
“The annual risk of human injury from space debris is less than 1 in 100 billion,” ESA officials wrote in an FAQ. This is about 65,000 times less than the risk of being struck by lightning.
ESA will keep us informed of ERS-2's dramatic return to Earth over the coming days. So keep checking back here at Space.com — and we'll pass along the important details, including whether or not you'll be able to see the satellite's remnants streaming across your sky.
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