The ERS-2 Satellite Safely Reenters Earth’s Atmosphere above the Pacific Ocean

On February 21, 2024, the European Space Agency’s (ESA) ERS-2 satellite successfully completed its atmospheric reentry over the North Pacific Ocean without causing any damage to property. The ERS-2 satellite, which was launched in 1995, provided invaluable data on Earth’s land surfaces, ocean temperatures, ozone layer, and polar ice extent over its almost 30-year lifespan. It also played an important role in monitoring and responding to natural disasters.

The decision to deorbit ERS-2 in 2011 was made due to growing concerns about orbital debris and its potential hazards to current and future space activities. ESA’s Director of Earth Observation Programmes, Simonetta Cheli, stated that the ERS satellites have provided new insights into our planet, including the chemistry of our atmosphere, the behavior of our oceans, and the impact of human activities on the environment. These insights have created new opportunities for scientific research and applications.

The atmospheric reentry of ERS-2 was closely monitored by an international campaign involving the Inter-Agency Space Debris Coordination Committee and ESA’s Space Debris Office. Uncontrolled atmospheric reentry has been a common method for disposing of space objects at the end of their missions. Tim Flohrer, Head of ESA’s Space Debris Office, mentioned that objects similar in size or larger than ERS-2 reenter the atmosphere multiple times each year. Throughout the 67 years of spaceflight, thousands of tons of artificial space objects have reentered the atmosphere with very few cases causing damage. There has never been a confirmed report of a human injury from space debris.

ERS-2’s reentry was considered “natural” because all of its remaining fuel was depleted during deorbiting to minimize the risk of an internal malfunction that could cause the satellite to break up into pieces while still at altitudes used by active satellites. As a result, ESA had no control over ERS-2 during its reentry, and the only force driving its descent was the unpredictable atmospheric drag. However, predicting the time and location of a natural reentry is challenging until the final few hours of the satellite’s life in space.

While natural reentries have been the traditional method, ESA is now committed to the long-term sustainability of space activities through their “ESA Zero Debris approach.” This approach aims to mitigate the creation of space debris and ensure the safest possible reentry for satellites at the end of their operational lives. ESA encourages other organizations to follow a similar path by initiating the community-led Zero Debris Charter initiative. Future missions conducted by ESA are designed for controlled reentries, allowing spacecraft operators to ensure that the satellites come down in sparsely populated areas like the South Pacific Ocean.

ESA also strives to dispose of its older satellites, including ERS-2, Aeolus, Cluster, and Integral, in more sustainable ways than initially planned. The legacy of ERS-2 and its predecessor ERS-1 lies in their role as the most sophisticated satellites ever developed and launched by Europe. These satellites collected valuable data for over 15 years, including important information about atmospheric ozone. The ERS heritage datasets are currently curated and made accessible through ESA’s Heritage Space Programme.

The ERS satellites paved the way for various successor missions dedicated to studying Earth’s changing world, such as Envisat, MetOp weather satellites, ESA’s Earth Explorer scientific research missions, and the Copernicus Sentinels. These missions, combined with ERS heritage data, contribute to identifying and understanding changes in our climate. ESA’s Heritage Space Programme Manager, Mirko Albani, emphasized that pioneering new technologies that later become operational to support services like weather forecasting and climate monitoring benefit citizens worldwide.

To wrap it up, the successful atmospheric reentry of ESA’s ERS-2 satellite marks a significant milestone in space safety and sustainability. With a shift towards controlled reentries and efforts to reduce space debris, ESA is actively ensuring the long-term viability of space activities while leveraging the valuable legacy of past missions to support research and benefit humanity.