Rising number of satellites could bring catastrophic collisions in space

Measures to combat the threat posed by space debris may not be enough to prevent collisions in Earth orbit, as companies prepare to launch unprecedented numbers of satellites, according to new research.

The findings come ahead of the launch of the first ‘mega-constellations’ of communications satellites, which the researchers say will present an increased risk to Earth’s space environment unless action is taken to reduce their impact.

Companies such as Boeing, OneWeb and SpaceX plan to launch constellations of between 720 and 4,425 small, low-cost satellites as early as next year in an effort to provide high-speed internet coverage worldwide. Many smaller satellites – especially CubeSats, a type of satellite used in space research – are expected to be launched at the same time.

A team of engineers – led by Dr Hugh Lewis, senior lecturer in aerospace engineering at the University of Southampton, working with the European Space Agency – undertook a study into the effects of constellations and small satellites on the space environment.

The engineers used the University of Southampton’s space debris model and Iridis High-Performance Computing facility to simulate the effects of large constellations and small satellites over a 200-year period.

The simulation was based on the existing satellite population and predicted future launches, including a mega-constellation and small satellites, with more than 300 different scenarios being investigated.

It revealed that adding a mega-constellation into space resulted in a 50% increase in the number of catastrophic collisions – involving the complete destruction of a satellite – over the 200 years, with potentially serious consequences for other satellites and the services they provide, as well as financial implications for the operators.

“There has been a paradigm shift in the manufacturing of satellites,” said Lewis. “The cost of making a single communications satellite usually runs to hundreds of millions of pounds, but mass-produced satellites will potentially be much cheaper.”

The research concluded that space debris mitigation guidelines need to be updated to incorporate measures to address mega-constellations and small satellite traffic. Other methods to decrease the likelihood of collisions could include:

•      Decreasing the time that satellites spend in low Earth orbit after the end of their mission. The current guidelines stipulate a maximum of 25 years to bring a satellite out of orbit, a process that can take it across the orbits of other satellites

•      Making satellites smaller and lighter

•      The addition of propulsion systems and other features to small satellites

•      Extending a satellite’s active lifespan so that fewer need to be launched

•      Deploying missions to remove faulty satellites from orbit.

“The good news is that there are opportunities for mega-constellation operators to address these issues, through good design and by aiming to do better than the minimum required of them,” said Lewis.

The team also included engineers from Clyde Space, Belstead Research, Airbus Defence and Space, the Braunschweig University of Technology in Germany, and the National Research Centre in Italy.