What To Know About The European Satellite Hurtling Toward Earth This Week

Topline

ERS-2, a satellite commissioned by the European Space Agency nearly 30 years ago, is set to reenter the Earth’s atmosphere this week—though the ESA said this poses an extremely low risk to people, as most of the spacecraft is expected to disintegrate into the atmosphere with remaining debris expected to hit the ocean.

The ERS-2 satellite is expected to reenter the atmosphere Wednesday. (Photo by Paolo Nespoli – … [+] ESA/NASA via Getty Images)

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Key Facts

ERS-2, the second in a series of satellites launched by the European Space Agency to collect information on the Earth’s surface and oceans, is reentering the atmosphere almost three decades after it began its mission in 1995.

The satellite will have a “natural” reentry to Earth, meaning it used up its remaining fuel prior to reentering the atmosphere to lower the risk of a dangerous explosion, according to the ESA.

The ESA is currently estimating the satellite will reenter the atmosphere Wednesday morning Eastern time, with a margin of error of about 12 hours, according to its predictions last updated Monday morning.

But because the reentry is “natural,” the satellite’s reentry cannot be controlled by the ESA since the satellite lacks fuel and its batteries and communications were switched off, meaning the time and location of its reentry cannot be predicted.

The exact reentry time and location of the satellite is difficult to predict because of the varying density of Earth’s atmosphere and unpredictable solar activity, the ESA said.

The majority of the debris from the satellite’s reentry will burn up in the Earth’s atmosphere, the ESA said, and the remaining debris, which do not contain toxic or radioactive substances, will likely fall into the ocean.

Surprising Fact

The risk of an individual being hit by space debris is extremely low—less than one in 100 billion, according to the ESA. That rate is 1.5 million times lower than the risk of being killed in an accident at home, 65,000 times lower than the risk of being struck by lightning and three times lower than being hit by a meteorite, the ESA said.

Key Background

ERS-2 launched four years after a similar satellite, ERS-1, with certain technological advancements, though both were commissioned to collect data on the Earth’s surface, polar ice caps, oceans and natural disasters. The ERS-2 mission lasted 16 years, until the ESA began to deorbit the spacecraft in 2011. The satellite underwent a series of 66 deorbiting maneuvers between July and August 2011, and the altitude of its orbit was lowered from 785 km to about 573 km to reduce the chance of collision with other satellites. The deorbiting measures were carried out to ensure the satellite’s reentry within 15 years, and the ESA said it is set to reenter on schedule. At the time the ERS-2 mission completed, Volker Liebig, the ESA’s Director for Earth Observation Programmes, said the agency will “continue exploiting data gathered by ERS-2, especially the radar imagery,” which will help scientists better understand the Earth’s climate.

Big Number

5,057 pounds, or 2,294 kilograms. That’s how massive the ERS-2 satellite is, the ESA said, though it clarified objects of this size reenter Earth’s atmosphere about once every week or two.

Tangent

The ESA said the short-term environmental impact of burning space debris is “modest” because the particles created during reentry are too large to spark chemical reactions with the atmosphere. To limit the long-term environmental impact of space debris, the ESA’s Space Debris Office researches and develops methods to mitigate the creation of space degree, and the ESA unveiled a “Zero Debris” goal for space missions by 2030.