Abandoned satellites may be able to be remotely grabbed and removed from important orbits around Earth in the future. The University of Toulouse has developed a tracking satellite that uses magnetic forces for this purpose.
Magnetic force
A good way to clean up space debris has been sought for years. One efficient way is to collect and remove them with another object. The biggest challenge here is making sure that such an uncontrolled, fast-spinning and heavy-weighing object, clings properly and stays put.
Previously, techniques such as robotic arms, nets and harpoons were experimented with for this purpose, but all these techniques proved to be ineffective. Researcher Emilien Fabacher from the Institut Supérieur de l'Aéronautique et de l'Espace, part of the University of Toulouse, has added a new element; magnetic grasping.
"With satellite clearance, it is much better if you can stay at a safe distance, without the need to come into direct contact and risk damaging the tug and the satellite to be removed," Emilien said. "So the idea I'm exploring is to apply magnetic forces; to both attract and repel satellites."
Satellites together
This magnetic attraction is also seen as a safe method to leave multiple satellites in dense assemblies in space. Such 'satellite swarms' are well suited for astronomical observation and exploration of Earth; if their position remains stable, together they can act as a giant telescope.
In this way, the satellites to be removed also no longer need to be pre-fitted with additional attributes. Instead, such a 'space tug' influences the satellites to be removed by using their 'magnetorquers': reliable electromagnets already present on the satellite to orient themselves based on the Earth's magnetic field.
The strong magnetic field required by the 'search satellite' is created by super attracting wires that are cooled. The magnetic satellites can also help keep several satellites flying in a precise formation, according to an ESA expert.
ESA
For his PhD research, Emilien investigated how the eventual guidance, navigation and control techniques would work in practice. To do so, he combined a rendezvous simulator with magnetic interaction models, while also taking into account the constantly changing state of the Earth's magnetosphere.
His research is supported by ESA, which has also been researching the most efficient method of removing space debris for years. Among other things, he visited an ESA's technical facility in the Netherlands. His method came about partly after several discussions with ESA experts. "The first surprise was that theoretically it would indeed be possible. We were not sure, but the method turns out to work fine."
ESA, meanwhile, is also testing various techniques to remove abandoned satellites. Just last month, for example, it tested a satellite that removes old satellites using a sophisticated robotic arm.
By: Kelly Bakker
Source: Institut Supérieur de l'Aéronautique et de l'Espace
