This story is part of The Salt Lake Tribune’s ongoing commitment to identify solutions to Utah’s biggest challenges through the work of the Innovation Lab.
If you feel Earth is a little too plain compared to some of its flashier neighbors like Saturn with its fancy rings there may be good news for you.
“Earth is on course to have its own rings,” said University of Utah professor Jake Abbott. “They’ll just be made of junk.”
There are 170 million pieces of space junk in orbit around the Earth. Most of them are quite small, but 23,000 of those are larger than a softball and concerning enough to be tracked by the Department of Defense. Space junk endangers space flights, orbital missions, and the astronauts who pilot them.
Space junk even falls to Earth. Usually, it breaks up in the atmosphere, but not always. An estimated 200 to 400 pieces of debris fall each year.
Earlier this year, a portion of a Falcon 9 launch vehicle made an “uncontrolled reentry” and lit up the night sky. A 5-foot section of the vehicle survived reentry, landing on a farm in Washington State.
Space junk, considered a type of pollution, has grown dramatically since 1957. We have 7,500 metric tons of junk in orbit – the equivalent of 1,100 elephants floating over our heads. The size of the herd is projected to continue to grow exponentially unless we do something about it.
“Most of that junk is spinning,” Abbott said. “Reach out to stop it with a robotic arm, you’ll break the arm and create more debris.”
So how do you get junk out of space? The answer, Abbott says, is magnets.
Abbott is a professor of robotics at the University of Utah, but what really pulls him in are magnets.
He recalls a presentation he saw as a graduate student at Johns Hopkins University.
“Under a microscope, they had this tiny maze with almost a little submarine in it. It moved forward and backward and turned,” said Abbott, “working its way through the maze.” A task completed entirely with magnets.
“Way simplistic compared to what we do now,” Abbott said, “but it seemed like magic.”
The magic led to post-doctoral studies at the University of Zurich in Switzerland where Abbott worked mostly on applications of magnets to surgery. He spent years working with a team on how to get a microscopic “submarine” to swim down through a human eye and deliver drugs to the retina.
“It took years to develop but the math used is the foundation for everything we do now,” said Abbott.
“Everything” includes using magnets to guide precision virtual reality eye surgeries.
“If it takes 30 surgeries before a surgeon is really competent, we want those first 30 or more surgeries to be on virtual patients, and we want them to be as realistic as possible.”
Abbott’s system uses magnetic fields to create the sensation of real surgical pressure with a virtual eye.
“I work a lot with the Moran Eye Center,” Abbott said.
His lab is also working on making colonoscopies more palatable. Using capsule-based cameras, they are developing a system for moving the capsules with precision using magnets. Their current design is a two-part capsule-cam where the two ends are connected with a short, rubbery chord.
“The magnets would move the cam through you like an inch worm,” said Abbott. “Swallow a capsule, lie on a table for a couple hours, you’re done.”
He notes that fear and hesitancy around colonoscopies are a major barrier to early detection of colon cancer.
Then, there’s space junk.
You might imagine space junk as a lot of metal, and much of it is, but it’s not all magnetic.
So magnets won’t work, right?
“They will work,” Abbott said, “because of eddy currents.”
The principle and his team’s findings applied to space junk are spelled out in a recent article for Nature, but let’s break it down.
You have a spinning piece of nonmagnetic space junk that can conduct electricity.
You extend magnets toward it on the end of robotic arms.
The magnets spin. When they spin, they activate eddy currents - electrical currents shaped like eddies (or whirlpools) in the object - that create their own magnetic field.
These activated magnetic fields push back on the field that created them.
Use a lot of careful math and modeling, and suddenly you can use controlled force and torque to slow the spinning object, move it around, collect it.
The short version: “We’ve basically created the worlds first tractor beam,” said Abbott. “It’s just a question of engineering now. Building and launching it.”
Science in practice
Eddy currents are a strange concept. See it in practice as this MRI machine makes a heavy block of (non-magnetic) aluminum fall in slow motion:
Want to understand the underlying principle (and be deeply entertained)? Here’s Youtube hero Mehdi Sadaghdar (aka, ElectroBoom)’s heavily bleeped explanation of eddy currents: