Space

Can magnetic space tugs clean up space junk?

Artist's concept of a magnetic tug nearing a derelict satellite
Artist's concept of a magnetic tug nearing a derelict satellite
View 3 Images
The tug's technology could help satellites to fly in formation, such as with the Darwin telescope array
1/3
The tug's technology could help satellites to fly in formation, such as with the Darwin telescope array
Artist's concept of a magnetic tug nearing a derelict satellite
2/3
Artist's concept of a magnetic tug nearing a derelict satellite
Derelict satellites could in future be grappled and removed from key orbits around Earth with a space tug using magnetic forces
3/3
Derelict satellites could in future be grappled and removed from key orbits around Earth with a space tug using magnetic forces

An ESA-funded scientist is developing a magnetic space tug to combat the growing problem of space debris. The tugs could lock onto derelict satellites and deorbit them before they become a hazard to navigation, and because they use cryogenic magnets, they wouldn't have to even touch the derelicts and the targets wouldn't need to be specially modified for towing.

Depending on how it's defined, there are over 500,000 pieces of debris or "space junk" orbiting the Earth, ranging in size from old launch vehicles and dead satellites down to flecks of paint. Because they travel at tens of thousands of miles per hour, even the smallest object can strike with the force of a meteor, and if a large one should hit a satellite, the impact could turn them both into deadly clouds of shrapnel.

So how do we remove this debris before the number of objects grow and it becomes a hindrance to space travel itself. Many solutions are being studied, and one key area is figuring out how unmanned space tugs can grapple with derelict satellites so they can be towed down into the Earth's atmosphere or out to so-called graveyard orbits.

Derelict satellites could in future be grappled and removed from key orbits around Earth with a space tug using magnetic forces
Derelict satellites could in future be grappled and removed from key orbits around Earth with a space tug using magnetic forces

Funded by ESA's Networking/Partnering Initiative, Emilien Fabacher of the Institut Supérieur de l'Aéronautique et de l'Espace at the University of Toulouse has come up with a system using magnetic fields generated by superconducting wires cooled to cryogenic temperatures. For his PhD research, he has been using a rendezvous simulator with magnetic interaction models to study how to guide, navigate, and control such tugs.

"With a satellite you want to deorbit, it's much better if you can stay at a safe distance, without needing to come into direct contact and risking damage to both chaser and target satellites," says Fabacher. "So the idea I'm investigating is to apply magnetic forces either to attract or repel the target satellite, to shift its orbit or deorbit it entirely."

The tug's technology could help satellites to fly in formation, such as with the Darwin telescope array
The tug's technology could help satellites to fly in formation, such as with the Darwin telescope array

The beauty of the method is that it not only eliminates physical contact with the target, but the satellites doesn't need to be specially designed for the magnetic tug to lock on. Low-Earth satellites are equipped with magnetorquers, which use the Earth's magnetic field to keep them oriented and prevent tumbling. The cryogenic magnets would be strong enough to use these magnetorquers like a built-in towing eye.

A bonus of the technology is that it could also be used to help keep satellites flying in formation for complex arrays, such as space telescopes. Using their attraction and repulsion, the satellites could be kept within 10 to 15 m (32 to 50 ft) with a precision of 10 cm (4 in) and an attitude of one to two degrees.

Source: ESA

4 comments
Bob
You've got to be kidding. Even an extremely strong magnetic field doesn't have much range in comparison to the size of the magnet. Decelerating junk would require getting very close and would likely also slow down the chaser satellite. Theoretically, you could transfer the kinetic energy from the object being slowed to the chaser but that would be nearly impossible to balance at such close distances. The ferro magnetic composition of most of the objects will be little to none. Besides, the larger dead satellites can be tracked and are small in number compared to the junk.
Douglas Bennett Rogers
This material took a lot of energy to put up. It ought to be collected and put into a higher orbit for future use.
Catweazle
Not much satellite junk is made of ferromagnetic material AFAIK.
ljaques
This will be perfect training for the future Space Corps cadets, flying grabber ships to take the space junk out to the orbiting salvage yard.
Thanks for reading our articles. Please consider subscribing to New Atlas Plus.
By doing so you will be supporting independent journalism, plus you will get the benefits of a faster, ad-free experience.