A 5,000-Pound Satellite Is Falling Back to Earth This Week—and Will Likely Land in the Ocean

The reentry of the satellite, called ERS-2, is part of an intentional effort by the European Space Agency to reduce orbital debris

An illustration of the ERS-2 satellite floating in space; orange and blue rectangle instruments on the right resemble solar panels, while a 'K' shaped grey panels extend on the left. An orange and gray box sits in the middle, connecting these two parts.
An illustration of the ERS-2 satellite. European Space Agency

After a nearly 30-year journey in space, a 5,000-pound European Space Agency (ESA) satellite, known as ERS-2 (European Remote Sensing 2), is expected to fall back to Earth on Wednesday morning Eastern time.

While this may sound alarming, officials encourage the public to stay calm—the odds of a person being injured by the falling space junk stand at just one in one billion, reports the Agence France-Presse (AFP). When it reaches roughly 50 miles above our planet, the vast majority of the satellite will break apart and burn up in the atmosphere. Any fragments that do continue falling will be non-toxic and non-radioactive, and they’ll most likely splash into the ocean.

“The largest fragment of the satellite that could reach the ground is 52 kilograms (115 pounds),” Henri Laur, an Earth observation researcher with the European Space Agency, said at a press conference Tuesday, per the AFP.

A person is 65,000 times more likely to be struck by lightning and 1.5 million times more likely to be killed in an accident at home than to get hit with a falling chunk of satellite, per the ESA.

However, the space agency remains uncertain about when the satellite will land. ERS-2 has used all its fuel and is making a “natural” or uncontrolled reentry, meaning it won’t be able to perform maneuvers as it descends.

As a result, its reentry, in large part, is dependent on activity from the sun. Later this year, the sun is expected to reach its solar maximum, a condition in which the star is at its most active. The occurrence is caused by an 11-year cycle in which the sun’s magnetic poles flip—then, after another 11 years, they flip back. During solar maximum, sunspots are prevalent and surface activity, such as flares, are more common than ever. This can affect the density of Earth’s atmosphere, making it more difficult for scientists to calculate the drag experienced by the satellite.

Earlier this week, scientists identified a 15-hour window of uncertainty for reentry. As of Tuesday afternoon, this had narrowed to 4.6 hours, with a predicted reentry at 11:32 a.m. Eastern time on Wednesday. The European Space Agency’s ERS-2 reentry blog routinely updates its refined estimates.

A graphic illustrating the timeline of the ERS-2 mission, from launch to data collection to reentry maneuvers, and finally ending with its descent and reentry.
A timeline of the ERS-2 mission and re-entry, spanning 1995 to 2024. European Space Agency

Launched in April 1995 from French Guiana, ERS-2 settled into orbit about 500 miles above Earth, collecting data on the planet’s oceans, polar ice caps, geology, forests and natural disasters, such as flooding and earthquakes. The mission’s data, freely accessible to the public, has been used to study climate change and the effect of human activity on the environment, among other applications.

Designed to last only three years, the ERS-2 mission endured for 16 years after launch, collecting valuable information until July 2011. At that time, operators used the last of the satellite’s battery and fuel—a choice meant to lower the risk of a future explosion—and maneuvered it to a lower altitude of about 356 miles. Had the ESA not taken that action, it would have delayed the satellite’s gradual return to Earth by up to 200 years.

“Deorbiting satellites at the end of their life and ensuring they reenter Earth’s atmosphere is a fundamental tool in keeping our busy space highways clear from defunct, lingering satellites, preventing collisions in orbit and mitigating the creation of further space debris,” the ESA wrote this month.

The European Space Agency has committed itself, by 2030, to generating zero space debris, which contributes to orbital collisions, explosions and even light pollution.

ERS-2 is falling at a rate of more than six miles per day, and its speed is increasing, the ESA said Monday. An object of similar mass to this satellite reenters the atmosphere every one or two weeks.

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