Envisat is a large satellite launched in 2002 to monitor the Earth’s environment and geography. Although it lasted five years beyond its original plan, the European Space Agency (ESA) lost contact with it in 2012. Envisat now poses the greatest Kessler syndrome threat in Earth’s orbit.
Two objects pass close to Envisat and could cause a collision. Considering Envisat’s mass of approximately 8,200 kilograms (18,000 lb), any crash between it and other satellites or pieces of space junk would be catastrophic and create a large debris field that would be nearly impossible to clean up.
The wreckage of Envisat would be so immense that the potential chain reaction of collisions proposed by the Kessler syndrome is the real danger, and Envisat represents its greatest risk.
Currently, the satellite is expected to continue in orbit for approximately 150 years before falling to Earth, which greatly increases the probability of an accident. For this reason, special considerations have been made to create a spacecraft capable of removing Envisat from orbit.
Envisat is perhaps one of the greatest ironies of our space program: A satellite that was celebrated for helping us to understand the health of the Earth’s environment is now one of the greatest risks to its orbital field.