Earth’s pollution problem extends out into space
Urgent action is needed to tackle the junk accumulating in orbit
Sometime in 2025, a European spacecraft will extend four robotic arms around a 100kg piece of metal junk in orbit at an altitude of 800km. Then, embraced in a hug of death, the craft and its target — a redundant rocket stage — will hurtle back towards Earth, burning up harmlessly in the upper atmosphere.
The €100m ClearSpace mission will be the first large-scale demonstration by a space agency of technology to tackle the menace of orbital debris. It is an overdue move against a growing threat to the satellites on which modern life depends — communications and broadcasting, navigational signals, weather and environmental monitoring. According to the European Space Agency, Earth is surrounded by more than 3,000 abandoned satellites, 34,000 other objects larger than 10cm and millions of small fragments travelling fast enough to damage spacecraft. At least one active telecoms satellite has already been destroyed in a collision and experts fear a series of catastrophic failures as thousands more satellites are launched in the 2020s.
This accumulation of rubbish extends into orbit the “tragedy of the commons” that has led to so much pollution on Earth. Anyone can benefit from exploiting space but no one has an incentive to keep it clean. Solutions will depend on developing international rules to force satellite operators to remove redundant spacecraft from dangerous zombie orbits, while coming up with new technology to remove the junk already up there.
The 1967 Outer Space Treaty, the foundation of international space law, was drawn up when few anticipated how many satellites would be launched in decades to come. It is vague about responsibility for junk almost to the point of uselessness. There is little chance of amending the treaty in the near future but various voluntary codes have been drawn up for satellite operators, such as the 2007 UN Space Debris Mitigation guidelines, which need strengthening and enforcing through national governments and industry bodies.
Top priority is for every satellite to include a built-in de-orbiting mechanism that propels it to burn up safely at the end of its life. Otherwise the operator must contract with someone else to bring down its satellite. A few private companies are developing their own technologies to serve the junk removal market that they expect to emerge later in the 2020s. Although robotic grabbing like ESA’s ClearSpace seems the most popular clearance technology, others including harpooning the junk and catching it with a net are in contention too. However it is done, large-scale investment in space junk removal and prevention by both private and public sectors will be essential if we are to prevent catastrophic collisions in space in the decades to come.