Leonard David's INSIDE OUTER SPACE

ERS-2 artwork.
Image credit: ESA

That incoming European Remote Sensing (ERS-2) is closing in on a nose-dive into Earth’s atmosphere.

Tipping the scales at an estimated 2.3 tons (2,294 kilograms), when and where the defunct spacecraft completes its final orbit is an unknown.  ERS-2 was launched on April 21, 1995.

Meanwhile, the European Space Agency’s (ESA) latest prediction is that ERS-2’s demise is now heading toward re-entry on February 21 at 15:19 UTC (16:19 Central European Time).

Image credit: ESA’s ESOC operations center, Darmstadt, Germany

“The uncertainty in this prediction is now less than one day (+/- 18.82 hours),” ESA satellite trackers add. “Please note that all predictions are still affected by significant uncertainties.”

Breaking up – easy to do?

ERS-2 will break up into fragments as it plunges through Earth’s atmosphere.

A vast majority of these will “burn up” in the atmosphere, ESA experts explain, although some fragments could reach Earth’s surface. Given that the Earth is largely ocean water-rich, chances are for splash down of any remaining spacecraft components.

Image credit: ESA’s ESOC operations center, Darmstadt, Germany

“No intervention can be made from the ground, so ERS-2 will return entirely naturally – now a common occurrence as on average one spacecraft reenters Earth’s atmosphere per month,” an ESA statement explains.

Entirely naturally

However, there are those that see the fall of ERS-2 as a calling card from space that doubles as a wake-up call – and on several fronts.

Ewan Wright is a PhD candidate at the University of British Columbia and Junior Fellow of the Outer Space Institute. He is actively focused on the sustainability of the outer space environment.

Credit: CORDS/The Aerospace Corporation

ERS-2 is a three decade old Earth Observation satellite with a mass about that of a Ford F-150, Wright said. “ERS-2 won’t burn up entirely when it reenters the atmosphere, so there is a chance that debris will hit someone on the ground, or disrupt air traffic.”

Uncontrolled re-entry

Wright told Inside Outer Space that, fortunately, the probability of someone getting hit is small. “But if we keep doing this again and again, someone someday will get hurt.”

Last year, 30 satellites larger than 500 kilograms uncontrollably reentered the atmosphere.

In total, in 2023, about 55 tons of satellite reentered randomly, Wright stated. ESA was responsible in lowering ERS-2’s orbit to make sure it didn’t become permanent space debris, he said.

Launch and reentry particle emissions in the Earth’s stratosphere.
Image credit: The Aerospace Corporation

“But in the future, all large satellites should do controlled reentries. Operators should control them to reenter over the oceans, away from people, aircraft and ships,” Wright concluded.

Hot topic

The incoming ERS-2 is something that happens quite regularly with defunct satellites, said Leonard Schulz, a researcher at the Technische Universität Braunschweig’s Institute of Geophysics and Extraterrestrial Physics in Braunschweig, Germany.

Such falls will only increase in the future, Schulz added, due to the growing number of objects brought into low Earth orbit.

Schulz said that there’s need to consider the effects on the atmosphere from spacecraft re-entry, a hot topic that ESA is evaluating.

“Today, we are lacking information on many aspects when it comes to materials released and subsequent effects on the atmosphere,” Schulz pointed out to Inside Outer Space.

Satellite reentries are a good opportunity to gather observational data with measurement campaigns, Schulz advised. However, such uncontrolled reentries as with ERS-2 are extremely difficult to observe, he said, as the uncertainty of where the satellite reenters is so high.

Chunks of space junk rained down in Australia, later identified as SpaceX leftovers from its Crew-1 Mission that flew in 2020-2021.
Photo courtesy: Brad Tucker

“But controlled reentries provide great measurement opportunities,” Schulz concluded, “which should be a focus in the future!”

Long-term impact

ESA organized a dedicated event in January 2024 to address the topic of satellite leftovers and pollution within Earth’s atmosphere.

ESA also carried out two studies on the atmospheric impact of spacecraft reentries in 2019. They concluded that the short-term impact on the atmosphere due to the burn up of a single spacecraft is modest, primarily because the particles created during a reentry are generally too large to react chemically with the atmosphere.

Credit: The Aerospace Corporation/Center for Space Policy and Strategy

On the other hand, what about long-term impact?

In a recent study issued last year, a research team led by the U.S. National Oceanic and Atmospheric Administration (NOAA) detected in Earth’s stratosphere more than 20 elements that mirror those used in spacecraft-building alloys.

Given projected launch rates from countries around the world, the NOAA research team calculated that in the next few decades, up to half of stratospheric sulfuric acid particles would contain metals from reentry.

Difficult to study, complex to understand

But what impact these space junk-laden particles could have on the atmosphere, the ozone layer and life on Earth is yet to be evaluated.

Image credit: NOAA

“Changes to the atmosphere can be difficult to study and complex to understand,” explains Purdue University’s Daniel Cziczo, professor and department head of Earth, Atmospheric, and Planetary Sciences. He took part in the NOAA-issued report.

“But what this research shows us is that the impact of human occupation and human spaceflight on the planet may be significant,” Cziczo adds, “perhaps more significant than we have yet imagined. Understanding our planet is one of the most urgent research priorities there is.”

For details on this NOAA research, go to “Space Pollution: Cautionary News” at:

https://www.leonarddavid.com/space-pollution-cautionary-news/