Over 14,000 pieces of junk are clogging up low Earth orbit, but this number could be reduced by a new invention that involves a satellite using the plasma exhaust of its ion engine to knock dangerous chunks of space junk into the atmosphere where they can burn up safely.
The huge amounts of space junk in orbit, ranging from nuts and bolts to rocket fairings and dead satellites, pose a serious hazard to satellites and the International Space Station, which has to regularly take evasive action to dodge space shrapnel, much of which is moving faster than a bullet.
Therefore, scientists and engineers have been working on ways to clean up low-Earth orbit. Most solutions proposed have included spacecraft that could grab space junk with robotic arms, nets and tethers. The problem with these ideas, however, is that much of the junk is tumbling. This means there’s a risk of the spacecraft getting caught up in the chaotic motion.
A non-contact method would be safer, and one proposal is to use the exhaust of a spacecraft’s ion engine to gradually but firmly push against a piece of space debris, slowing the debris down until it falls out of orbit and into the atmosphere.
However, an ion engine is designed to push a spacecraft forward. Firing an ion engine’s plasma exhaust at a piece of space junk would therefore push the removal satellite away from the junk.
Now though, Kazunori Takahashi of Tohoku University in Japan has developed a solution. Rather than having just one exhaust, a removal satellite could have two exhausts pointing in opposite directions. The thrust from each exhaust would cancel the other out, allowing the removal satellite to hold station while it goes about its job of deorbiting space junk.
Takahashi calls his system a “bidirectional plasma ejection-type electrode-less plasma thruster.” An ion engine works by using an inert gas as a propellant; often this gas is xenon, but Takahashi used argon.
“It can be operated using argon to a similar efficiency as with xenon, but providing a reduced cost for the propulsion device,” Takahashi told Space.com.
The gas fills a chamber, with a cathode on one side producing a cloud of electrons that are then attracted to a positively charged discharge wall. On their way, they interact with the gas and ionize it. Ionized gas is called a plasma, and it is electrically charged such that it can be directed and accelerated by electromagnetic fields out through a thruster nozzle, producing thrust.
In Takahashi’s system, “the plasma can flow along the field lines towards both sides, providing the bi-directional plasma ejection,” he said.
Source & full article: Future Inc.
