European shield in space: how SSA saves satellites from debris and solar storms
Diana Parkhouse, Unsplash
We depend on satellites far more than we might think, from weather forecasting to GPS systems and telecommunications. But with that comes increased danger - the Earth's orbits are increasingly filled with space debris. The European Space Situational Awareness (SSA) system is the shield that protects these vital technologies from collisions, solar storms and even asteroids.
Even a tiny piece of debris the size of a balloon can disable a satellite. For example, in 2016, a tiny fragment penetrated the solar panel of the Sentinel-1A satellite of the Copernicus programme. The damage did not stop the mission, but it became an alarming signal. Such incidents are becoming more frequent: for example, in December 2024, Sentinel-2B had to urgently change its orbit to avoid a collision - data for that period was lost.
The main threat is in Low Earth Orbit (LEO), up to 2,000 kilometres above Earth. This is where most satellites, including the mega constellations for the global Internet, are centred. It is estimated that there are more than a million objects, ranging in size from 1 cm, orbiting LEO. These are not only inactive satellites and rocket fragments, but also the consequences of past collisions.
The European SSA system consists of three components:
- Space Surveillance and Tracking (SST) - a network of radars, telescopes and laser stations tracks objects in orbit. Thousands of measurements are recorded every day to help prevent collisions. More than 550 satellites are already connected to the EU SST system. On average, one high-risk incident is identified every week.
- Space Weather Events (SWE) - monitoring solar storms and radiation flares. Such events can disrupt navigation, communications and even power grids. In 1989, a powerful solar storm paralysed the power grid in Quebec for 9 hours. The EU is investing in predictive models for early warning.
- Near-Earth Objects (NEOs) - observing asteroids and comets that may pose a threat not only to satellites but also to the Earth itself. The EU is developing a catalogue of NEO physical characteristics and exploring possibilities for rapid reconnaissance and potential deflection of objects.
SSA is more than just monitoring. It gives satellite operators time to manoeuvre, allows them to assess the threat of large objects falling to Earth in advance and helps authorities prepare. For example, the recent fall of Falcon 9 debris in Poland was a reminder that space requires the same safety as Earth's infrastructure.
