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A Bi-Directional Plasma Thruster Could Deorbit Space Junk Safely

There are plenty of labs working on solutions to Kessler Syndrome, where there’s so much debris in low Earth orbit that rockets are no longer capable of reaching it without being hit with hypersonic parts of defunct equipment. While we haven’t yet gotten to the point where we’ve lost access to space, there will come a day where that will happen if we don’t do something about it. A new paper from Kazunori Takahashi of Tohoku University in Japan looks at a novel solution that uses a type of magnetic field typically seen in fusion reactors to decelerate debris using a plasma beam while balancing itself with an equal and opposite thrust on the other side.

Researchers have been working on two main categories of systems for the type of deorbiting work that might save us from Kessler Syndrome – contact and non-contact. Contact systems physically make contact with the debris, such as by a net or a grappling hook, and slow the debris to a point where it can deorbit safely. This method faces the challenge that most debris is rotating uncontrollably, and could potentially destroy the satellite trying to make contact with it if it move unexpectedly – adding to the problem rather than solving it.

Therefore, non-contact forms are in the accendency, as they allow a system designed to deorbit another satellite to stay a few meters away while still affecting its speed. Typically they use systems like lasers, ion beams, or in the case of Dr. Takahashi’s invention, plasma beams, to slow their intended target to a point where it can safely deorbit.

https://www.youtube.com/watch?v=dft7-yNSabc

Avoiding the Kessler Syndrome with Moriba Jah (https://www.youtube.com/watch?v=dft7-yNSabc)

Fraser discusses how to avoid Kessler syndrome with Dr. Moriba Jah

The problem with plasma beam based deorbiting systems is Newton’s third law – as the plasma is being directed toward the target, it is pushing the operational system away from the defunct one, essentially acting as a small plasma thruster. As the distance between the two increases, the slowing effect of the plasma decreases. To solve this problem, Dr. Takahashi, along with Christine Charles, Rod Boswell, and Akira Ando, presented a bi-drectional thruster in a paper in 2018 that counteracted the pushing force of the plasma used to slow the target with an equal force in the opposite direction, allowing it to maintain its position.

However, in that original paper, the thrust was too weak to effectively deorbit some of the larger potential targets for such a mission. So Dr. Takahashi set about improving the design by implementing a “cusp” type magnetic field. These are typically used in fusion reactors to ensure the plasma doesn’t interact with the wall of the magnetic chamber. The “cusp” of a field is a point at which two opposing magnetic fields meet and cancel out, creating a quick change in direction for the forces they apply. Ideally, this results in a stronger plasma beam.

That is what happened when Dr. Takahashi set up an experiment to test the new cusp system with the previous “straight-field” system that had proved too weak. He was a 20% improvement in the force the plasma thruster exerted on the target, resulting in a 17.1 mN push at the same power level. When he bumped up the power level to 5 kW (compared to the 3 in the original test), it showed an improved deceleration of about 25 mN, which is approaching the level of 30 mN expected to be needed to decelerate a 1 ton piece of debris in 100 days. It also had the added benefit of using argon as fuel, which is cheaper compared to the xenon typically used in plasma thrusters.

https://www.youtube.com/watch?v=D9Jf41w1ChI

How Do Satellites NOT Crash. And How Can We Keep It That Way? (https://www.youtube.com/watch?v=D9Jf41w1ChI)

Fraser discusses the difficulties of keeping satellites in orbit properly.

Even with this success, there’s still a lot of work to do before this becomes a fully fleshed out system. The experiment was run in a vacuum chamber, with the plasma thruster only 30 cm away from the target, as compared to the meters that would be required in a real orbital environment. In fact, the debris target will also move in comparison to the deorbiting system as it slows down, so it will have to strike a balance of maintaining distance from a slowing object as well as continuing to fire the decelerating beam at it. And finally, there is the disadvantage of it using literally twice as much fuel as other solutions that don’t require thrusters operating is opposite directions – while fuel might not be much of a concern for plasma thrusters, operating one over 100 days is sure to consume a lot of it.

With all that being said, any new solution to this potentially catastrophic problem is welcome, and Dr. Takahashi will likely continue work on developing this prototype. Someday soon you might even be able to watch a dual-thrust plasma engine blasting away at a large piece of space junk.

Learn More:

Tohoku University – Improved propulsion system may help remove space debris without contact

K. Takahashi – Cusp-type bi-directional radiofrequency plasma thruster toward contactless active space debris removal

UT – Orbital Debris is Getting Out of Control

UT – A new Method to Capture High-Resolution Images of Space Debris

News

California lawmakers pass bill banning law enforcement officers from covering their faces

The California Legislature on Thursday passed a pair of bills to prohibit on-duty law enforcement officers, including federal immigration agents, from masking their faces and to require them to identify themselves.

Senate Bill 627, written by Sens. Scott Wiener (D-San Francisco) and Jesse Arreguín (D-Berkeley), includes exceptions for SWAT teams and others. The measure was introduced after the Trump administration ordered immigration raids throughout the Los Angeles area earlier this year.

Federal officers in army-green neck gaiters or other face coverings have jumped out of vans and cars to detain individuals across California this summer as part of President Trump’s mass deportation program, prompting a wave of criticism from Democratic leaders.

Representatives for the U.S. Department of Homeland Security defend the face coverings, arguing that identifying officers subjects to them to retaliation and violence.

If supported by Gov. Gavin Newsom, the law would apply to local and federal officers, but not state officers such as California Highway Patrol officers. Wiener, when asked about that exemption on the Senate floor, declined to elaborate.

Leaders in Los Angeles County are exploring a similar measure to ban masks despite some legal experts’ view that the supremacy clause of the U.S. Constitution dictates that federal law takes precedence over state law.

The bill’s backers argue that permitting officers to disguise themselves creates scenarios where impostors may stop and detain migrants, which undermines public trust and ultimately hinders legitimate law enforcement operations.

“The idea that in California we would have law enforcement officers running around with ski masks is terrifying,” Wiener said in a brief interview. “It destroys confidence in law enforcement.”

Wiener’s bill allows exceptions for masks, including for undercover officers. Medical coverings are also allowed. .

Senate Bill 805, a measure by Sen. Sasha Renée Pérez (D-Alhambra) that targets immigration officers who are in plainclothes but don’t identify themselves, also passed the state Legislature on Thursday.

Her bill requires law enforcement officers in plain clothes to display their agency, as well as either a badge number or name, with some exemptions.

News

One Country Knew What to Do When Its President Tried to Steal an Election

Brazil just succeeded where we failed.

News

Charlie Kirk shooter remains at large. Here’s what we know about the search for a suspect.

A search was continuing Thursday for the person who shot and killed Charlie Kirk at an event at Utah Valley University. Kirk, a prominent conservative activist who co-founded the right-wing advocacy group Turning Point USA, was 31.

Authorities have not yet identified or apprehended a suspect nor specified a motive, but on Thursday officials revealed new details about the shooter’s movements, a weapon that was recovered and the investigation.

The Utah Public Safety Department and the Salt Lake City FBI office also posted two images of someone they called a “person of interest,” showing an individual appearing to be wearing a dark long-sleeve shirt, and a hat and sunglasses. It asked for the public’s help in identifying the person.

The FBI released 2 photos of a — The FBI said it is seeking the public’s help in identifying this person of interest in connection with the fatal shooting of Charlie Kirk at Utah Valley University.

FBI

Officials took two people into custody Wednesday in the wake of the shooting but later said neither was tied to the shooting and both were released.

Here is what we know so far about the ongoing investigation.

Suspect at large

Authorities said the suspect remained at large Thursday and that a manhunt is underway to identify and capture the person responsible. The FBI said it is offering a reward of up to $100,000 for information that leads law enforcement to identify and arrest the person or people involved in Kirk’s assassination.

Two law enforcement sources told CBS News Thursday that U.S. Marshals were assisting the FBI in tracking down the suspected shooter. The FBI remains the lead investigating agency but is working with Utah officials.

Utah Public Safety Commissioner Beau Mason said the suspect was a male who “blended in” with the college community and appears to be “college-age.”

Mason said investigators have been able to track the shooter’s movements before and after the assassination. He said the gunman is believed to have arrived on campus at 11:52 a.m. local time Wednesday and moved through stairwells to the roof of a building near where Kirk’s event was taking place, which was the shooting location.

Mason said the shooter moved to the other side of the building after firing a single shot, then jumped off and fled into a neighborhood off campus. Investigators contacted homeowners with cameras, and witnesses, to identify leads, he said.

Mason also said authorities “have good video footage” of the suspect, which they hope will help as they work to identify him.

Weapon recovered

FBI special-agent-in-charge Robert Bohls said Thursday that investigators recovered a “high-powered, bolt-action rifle,” which they believe was the weapon used in the assassination. It was found in a wooded area where the shooter fled and will be analyzed by the FBI, according to Bohls.

Investigators also have a footwear impression, palm print and forearm imprints that will be analyzed, the FBI official said.

The FBI’s Salt Lake City field office established a tip submission form where people can share information about the shooting. The agency said it has “full resources devoted to this investigation, including tactical, operational, investigative and intelligence.” It is investigating along with Utah state authorities.

A “targeted attack”

Kirk was struck in the neck at around 12 p.m. local time Wednesday by a single gunshot, which the perpetrator fired as Kirk addressed a large crowd at an outdoor “Prove Me Wrong” debate on Utah Valley University’s campus in Orem, Utah.

The “Prove Me Wrong” debate is a trademark event for Kirk’s Turning Point USA, a conservative organization focused on young people, where he would hold political debates with a group that usually consisted of left-leaning attendees. Kirk had visited the Utah school as part of a nationwide tour of college campuses that was scheduled to continue for the next two months. About 3,000 people attended the outdoor event, the Utah Department of Public Safety said in a statement.

While authorities have not specified a potential motive for the shooting, Mason said they believe it was a “targeted attack toward one individual.” Only one shot was fired, and Kirk was the only victim, according to the commissioner.

Utah Gov. Spencer Cox called the shooting “a political assassination,” while President Trump, in a video posted to Truth Social, blamed it on “radical left political violence,” which he said “has hurt too many innocent people and taken too many lives.” Mr. Trump vowed to “find each and every one of those who contributed to this atrocity.” Kirk was a close Trump ally and was credited with galvanizing younger voters during his campaign.

Bohls reiterated Thursday that investigators consider the shooting to be a “targeted event,” and do not believe there are lingering risks to the public.

Shooting location

A map produced by CBS News’ Confirmed team shows where Kirk was when he was shot — in the central courtyard of Utah Valley University, which is surrounded by campus buildings.

A university spokeswoman said Wednesday they believed the shot was fired from the Losee Center. A law enforcement source told CBS News that the gunman appeared to have fired from the building’s roof.

Video verified by CBS News shows a person running across the building’s roof in the moments after the shooting, about 400 feet from where Kirk was speaking. Authorities have not confirmed whether that person is connected to the attack. Drone video captured afterward shows police tape on the roof where the person was seen.

On Thursday, Bohls of the FBI said investigators had received over 130 tips and that those tips and other leads were being “fully investigated.”

Joe Walsh and

contributed to this report.

Emily Mae Czachor

Emily Mae Czachor is a reporter and news editor at CBSNews.com. She typically covers breaking news, extreme weather and issues involving social justice. Emily Mae previously wrote for outlets like the Los Angeles Times, BuzzFeed and Newsweek.