Magnetic Manipulation of Space Junk (Astronomy)

The solution to remotely deflecting potentially dangerous space debris, or to slowing damaged satellites into uncontrolled rotation in order to repair them, is called magnetic manipulation. In particular, the one proposed by the University of Utah exploits the currents induced by moving magnetic fields in the metal pieces constituting the space debris. All the details on Nature

They call it space junk, but it looks more like a volley of bullets. 27 thousand debris, the size of tennis balls that travel up to 28 thousand kilometers per hour: many would be over our heads, according to NASA. And this (of) discharge risks causing serious damage to satellites or spacecraft that are still functioning.

As on Earth, the garbage problem becomes more and more burdensome as the population (of orbiting objects, in the case of space) increases. The problem, in this case, is to understand how to handle it properly and – possibly – how to recover it where it is possible to repair the damage. A study published in Nature has discovered a new method to deflect orbiting debris without touching it through the use of rotating magnets .

Password: deviate but do not touch. The advantage of magnetic manipulation is precisely the possibility of performing it without contact, avoiding dangerous and destructive collisions between manipulator object and target. The concept is well proven and even reaches six degrees of freedom of movement in the case of ferromagnetic material . In the case of space debris , however, the metal of which they are composed is electrically conductive but does not contain an appreciable amount of ferromagnetic material.

When metal debris is subjected to a time-varying magnetic field , however, the electrons circulate inside in circular cycles, generating eddy currents that interact with the magnetic field itself. In the new study, the scientists showed that this physical feature allows the manipulation, with six degrees of freedom, of conductive objects by means of rotating magnets: the process transforms the debris into a real electromagnet, whose motion can then be controlled remotely. .

To be honest, the idea of ​​using induced magnetic currents to move objects in space is not new either, but until now it was limited to just one degree of freedom, such as a horizontal thrust. By using multiple sources of magnetic field in a coordinated way, however, the researchers figured out how to move objects in six degrees of motion, including rotation.

“What we wanted to do was manipulate it, not just push it, just like we do on Earth,” says Jake J. Abbott , professor of mechanical engineering at the University of Utah and head of the team that devised this new method. “This form of skillful manipulation has never been done before.”

With this new technique, it would be possible, for example, to stop a damaged satellite in uncontrolled rotation to repair it, a maneuver that – under normal conditions – would be highly risky. “You have to take this crazy object floating in space, and bring it to a position where it can be fixed by a robotic arm,” explains Abbott. “But if it’s spinning out of control, it could break the robot arm, creating even more debris.”

This method also allows you to manipulate particularly fragile objects. While a robotic arm could damage an object by applying excessive force, these magnets would apply a softer force to the entire object so that no sections are damaged.

To test the new technique, the team used a series of magnets to move a copper sphere on a plastic raft in a water tank (the best way to simulate slow objects in microgravity). The magnets not only moved the sphere into a square, but they also managed to rotate it.

“NASA is tracking thousands of space debris in the same way air traffic controllers track planes. You have to know exactly where they are to avoid accidentally crashing into them, ”says Abbott. “The US government and the governments of the world know about this problem because there is more and more stuff piling up with each passing day.”

To know more:

Watch the YouTube video of the University of Utah:

Featured image: 70 percent of all cataloged objects are in a low Earth (Leo) orbit, extending up to 2000 kilometers above the Earth’s surface. To observe the Earth, the probes must orbit at such a low altitude. The spatial density of objects increases at high latitudes. Note that the debris field shown in the image is an artist impression based on real data. However, the image does not show the debris in its true size or density – the debris is shown in an exaggeratedly large size to make it visible at the scale shown. Credits: Esa


Provided by INAF

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