Researchers are looking into a laser-based system that nudges space debris into different orbits to protect spacecraft and satellites.
As the amount of space debris in orbit increases, so does the risk that some of it will collide with manned and unmanned space assets.
It is estimated that around one million pieces of debris larger than a centimetre are in Earth’s orbit, and around 100 trillion pieces of old satellite are not being tracked.
West Virginia University (WVU) researchers believe that the best chance for preventing those collisions is an array of multiple lasers mounted on platforms in space. The lasers could be powered by AI and manoeuvre together in order to respond rapidly to debris of any size.
The work is currently in its early stages, and the team are verifying that the algorithms they are developing would be a cost-effective solution.
Team leader Hang Woon Lee is director of the Space Systems Operations Research Laboratory at WVU.
“Our goal is to develop a network of reconfigurable space-based lasers, along with a suite of algorithms. Those algorithms will be the enabling technology that make such a network possible and maximise its benefits,” he said.
If a natural object, like a micrometeoroid, hits a human-made object, such as the remains of a launch vehicle, the resultant debris can travel quickly enough that even a piece as small as a fleck of paint might have the force to puncture a telecommunications satellite or the side of the International Space Station.
That has become an urgent problem because space is becoming increasingly cluttered. In particular, Earth’s low orbit has attracted commercial telecommunications systems such as SpaceX’s Starlink, which brings broadband internet to subscribers.
Low orbit is also home to satellites used in weather forecasting and land-cover analysis, and is the staging ground for deep space exploration.
“That increased population of objects heightens the risk of collisions, endangers manned missions and jeopardises high-value scientific and industrial missions,” Lee said. He added that collisions in space can trigger a domino effect called the ‘Kessler syndrome’, which induces a chain reaction increasing the risk of further collisions, “making space unsustainable and hostile”.
Other researchers are developing debris removal technologies such as hooks, harpoons, nets and sweepers, but those only work on large debris. The laser-based approach should be able to handle debris of almost any size.
The suite of algorithms might work on lasers that are mounted on large satellites, or they might power lasers that live on their own dedicated platforms.
When a laser beam shoots a piece of debris, it nudges it into a new orbit through laser ablation – a process where a small portion of the debris is vaporised which generates a high-velocity plasma plume, pushing it off course.
“The process of laser ablation and photon pressure induces a change in velocity in the target debris, which ultimately alters the size and shape of its orbit,” says Lee. “This is where the motivation for using lasers comes into play. The ability to change the orbit of debris can be effectively controlled by a network of lasers to nudge or de-orbit space debris, avoiding potentially catastrophic events such as collisions.”
