The job is done. ESA’s second European Remote Sensing Satellite (ERS-2) has re-entered the Earth’s atmosphere over the North Pacific Ocean. The satellite returned between Alaska and Hawaii on February 21, 2024 at 18:17 CET (17:17 UTC). ERS-2 was launched almost 30 years ago on April 21, 1995. Together with ERS-1, it provided invaluable long-term data on the Earth’s surface, ocean temperature, ozone layer, and the extent of polar ice caps that transformed our understanding of the Earth system.

ERS-2’s return was “natural”. ESA used the last of its fuel, discharged its batteries and lowered the satellite from an altitude of 785 kilometers to 573 kilometers. This reduced the risk of collisions with other satellites and space debris. As a result, it was impossible to control ERS-2 at any point during atmospheric entry, and the only force pushing it down was unpredictable atmospheric resistance.

This extraordinary mission laid the foundation for many of today’s satellites and ESA’s position at the forefront of Earth observation, as well as leaving behind a remarkable legacy of data that continues to advance science.

The European Space Agency’s (ESA) ERS-2 satellite, Europe’s second remote sensing spacecraft, completed its re-entry into Earth’s atmosphere in a bright fireball over the North Pacific Ocean on February 21. Copyright: ESA

The return of ERS-2 is part of ESA’s wider efforts to ensure the long-term sustainability of space activities. These include ESA’s Clean Space Initiative, which supports the development of new technologies for more sustainable space missions in collaboration with the wider European space community, and the Zero Debris Approach, which will further reduce the amount of debris left behind both in and around Earth orbit. months future missions.

Launched in 1991, the European Remote Sensing Satellite ERS-1 carried a complex payload that included a synthetic aperture radar, a radar altimeter, and other powerful instruments for measuring ocean surface temperature and offshore winds. Overlapping ERS-1, ERS-2 was launched in 1995 with an additional sensor to study atmospheric ozone.

At the time of launch, the two ERS satellites were the most advanced Earth observation spacecraft ever developed and launched in Europe. These highly successful ESA satellites have collected a wealth of valuable data about the Earth’s surface, oceans and polar ice caps, and are designed to monitor natural disasters such as severe floods or earthquakes in remote parts of the world.

Both ERS satellites were built with a primary payload consisting of two dedicated radars and an infrared imager. Both were designed to be identical twins, but they had one important difference: ERS-2 included an additional device to monitor ozone levels in the atmosphere.

Shortly after the launch of ERS-2 in 1995, ESA decided to link the two satellites together in the first “tandem” mission, which lasted nine months. During this time, the increased frequency and level of data available to scientists provided a unique opportunity to observe changes in a very short period of time, as two satellites orbited the Earth only 24 hours apart.

In March 2000, computer and gyroscope control failure caused ERS-1 to be finally retired after well beyond its planned lifespan. In July 2011, ESA decided to also decommission ERS-2 and the process of deorbiting the satellite began.

ERS data has supported more than 5,000 projects over its lifetime, leading to nearly 4,000 scientific publications. The archived data that has provided us with a wealth of information to date is kept available and continually enhanced by the Heritage Space Programme, to create long-term data series with subsequent missions including Envisat, ESA’s Earth Explorer family and Copernicus Sentinels.