2,300 kg European satellite about to fall out of control

The European Space Agency's (ESA) European Remote Sensing Satellite 2 (ERS-2) is expected to fall back to Earth in February.

Illustration of ESA's ERS-2 satellite in Earth orbit. Photo: ESA — Illustration of ESA's ERS-2 satellite in Earth orbit. Photo: *ESA*

The ERS-2 satellite was launched into Earth orbit in April 1995 and completed its Earth observation mission in September 2011. ESA began preparing for the satellite's fall even before its primary mission ended, Space reported on February 8.

Specifically, ESA fired ERS-2's engines a total of 66 times in July and August 2011. These maneuvers consumed ERS-2's remaining fuel and lowered its average altitude from 785 km to about 573 km, significantly reducing the risk of collision with other satellites or space debris, while ensuring that ERS-2's orbit would drop quickly enough for it to re-enter the atmosphere within 15 years.

When it was launched, ERS-2 was the most sophisticated Earth observation satellite ever developed and launched by Europe. At the time of liftoff, it weighed 2,516 kg. Now, with no fuel, it weighs around 2,294 kg.

ERS-2 is large, but much larger objects have fallen back to Earth in recent times. For example, the 23-ton core stage of the Chinese-built Long March 5B rocket has fallen uncontrollably about a week after launch. Such reentry incidents have occurred three times in the past three years, a design feature that has outraged many space experts.

ERS-2’s descent will take much longer, up to 13 years. But the satellite is now low enough to be rapidly pulled down by atmospheric drag. This will accelerate in the coming days. The fall will be uncontrolled because ERS-2 has run out of fuel and experts can no longer fire its engines.

It is too early to predict where and when ERS-2 will hit Earth’s atmosphere, but it will likely fall into the ocean, as water covers about 70% of the planet’s surface. The satellite will disintegrate at an altitude of about 80 km. Most of the debris will then burn up in the atmosphere. According to the ESA, there is no need to worry too much about pieces falling to Earth’s surface, as they are not toxic or radioactive.

The odds of debris hitting a person are also extremely small. The risk of a person being injured by space debris each year is less than 1 in 100 billion, according to the ESA. That’s about 65,000 times lower than the risk of being struck by lightning.

Thu Thao (According to Space )

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