Dealing with "space junk" is imminent

For centuries, astronomers have marveled at the complex constellations, swept comets, and stable phases of the moon. However, in the 60 years since humans first broke through Earth's atmosphere in the 1950s, the skies have been packed with something less exciting: this is "space junk."

Space experts say at least 25,000 objects are currently racing over Earth, including abandoned rocket boosters, scrapped satellites and tiny pieces that disintegrate after various space missions are completed, some at speeds of 8 kilometers per second. Debris is increasing, hitting other debris, causing more debris and putting the spacecraft still in operation at risk.

If existing debris is not cleaned up to prevent further accumulation, such collisions are likely to grow exponentially. The resulting buildup makes orbital conditions dangerous, threatens astronauts' lives, and endangers valuable space technology and research. The entire track may be contaminated and unusable.

Space powers need to prioritize this issue to ensure the security and sustainability of the space economy for generations to come, but this will require large-scale cooperation and a lot of innovation.

Common "mess", shared responsibility

According to Newsweek, the recent high-profile collision has drawn expert attention to space debris. In 2009, the Iidium 33 communications satellite launched by the United States collided with Russia's abandoned Kosmos-2251 satellite, causing thousands of new pieces of debris to fly at high speeds in space. Although some of it burned up in Earth's atmosphere, more than 2,000 traceable pieces of debris still exist in space.

In 2021, debris from Russian anti-satellite tests caused crew members on the International Space Station (ISS) to hide in space capsules, ready to be evacuated. While they were unharmed at the time, earlier this year a piece of debris pierced a 5-millimeter-wide hole in the heat shield of one of the international space station's robotic arms.

From paint bucket-sized debris to school-bus-sized boosters, "space junk" in low-Earth orbit poses an almost immeasurable risk to decades of research and exploration efforts by scientists. As giant satellite networks like SpaceX's Starlink continue to launch, the risk is greater than ever.

Darren McKnight, a senior technology researcher at LeoLabs, a tech startup affiliated with stanford's Institute for International Studies, recognized the need to address this challenge. He said it would take leadership, but he said why can't we work together to clean up the accumulating "mess"?

Solution: Four-armed robot vs. magnet satellite

Due to concerns about debris, multiple organizations around the world issued a space industry debris statement in 2021, pledging to work to reduce debris and protect Earth's orbit, ensuring sustainability and safety for future generations.

Signatories include Airbus and Lockheed Martin, as well as many other well-known companies in the space manufacturing and travel sector. Some signatories, together with the Global Space Council for the Future, have brainstormed a "unified traffic management system" to prevent collisions, agreed on sustainability policies to which all stakeholders adhere, and created end-of-life removal technologies for decommissioned satellites and other debris.

The European Space Agency (ESA) is already working to clean up low-Earth orbit, where debris poses the greatest threat. The agency chose Swiss company ClearSpace to sign a $104 million contract to capture the large pieces and derail them. Lead engineer Muriel Richards said a space debris removal mission is scheduled to launch in 2025, launching a four-armed robot called ClearSpace-1 that will run like a claw.

"Debris rolls randomly," Richards said, "and the robot's movements match the speed of the object, slow down the roll, and then grab it." Finally, the robot places itself in an orbit back to the atmosphere. "Bringing debris into Earth's atmosphere causes them to burn or land harmlessly into the Pacific Ocean.

Another Japanese space startup, AstroScale, is working on a similar project. AstroScale is developing a spacecraft called ELSA-d, weighing up to 200 kilograms, which will be the world's first satellite to use magnets to collect space junk, linked to the U.S. Space Force's Orbital Prime Program.

Alternative: "locally sourced" reuse

Other plans include sending the debris further into "graveyard orbit," where they cannot interfere with most space travel and existing satellites or space telescopes. Some engineers hope that larger objects, such as scrapped rocket fuselages, could be reused for small space stations. Marshall Smith, senior vice president of NanoRack, a subsidiary of Voyager Space, believes this could be a cost-effective way to dispose of debris. They are currently working on how welding works in space so that materials in orbit can be put into use without the need to return to Earth.

As for smaller objects, such as debris from the International Space Station that has been damaged, there is still a responsibility for spacecraft and satellites in service to navigate to avoid potential impacts. Limiting the production of more tiny pieces is also crucial. Dylan Taylor, chairman and chief executive of Voyager Aerospace Holdings, wrote that on Earth, this means global cooperation between state and private companies that must avoid repeating the Iridium collision or the anti-satellite test collision at all costs.

Some companies have even partnered with the World Economic Forum to create a Spatial Sustainability Rating (SSR), which is expected to be launched in 2022. Any organization that voluntarily submits a form on its sustainability work during the implementation of a mandate will receive a score based on the mission's debris mitigation approach, measures taken to avoid collisions, consistency with international norms, etc. Taylor hopes the SSR will encourage the industry as a whole to reduce waste and increase transparency.

Warnings about "Kessler syndrome" are staged in real time

The European Space Agency warns that if the world "goes as usual", we may see "Kessler syndrome" playing out in real time. Named after former NASA scientist Donald Kessler, the term describes a potentially catastrophic domino effect similar to the fictional storm of debris in the 2013 sci-fi movie Gravity.

"Satellite collisions create orbital debris, and each collision increases the likelihood of further collisions, leading to an increase in debris bands around Earth," Kessler wrote in 1978, "and the flux of debris in such earth orbital zones could exceed the flux of natural meteoroids, affecting future spacecraft designs." ”

Accepting this challenge means saving lives and daring to spend money. In addition, it can also promote a stronger space economy. Newer tools for clean space and collision avoidance purposes, such as ELSA-d or ClearSpace-1, will need to be maintained indefinitely, and being responsible for debris will reassure satellite manufacturers, commercial astronauts and space organizations that space travel is safe.

Taylor said seizing the time to clean up space junk will demonstrate the space industry's commitment to sustainable development and pave the way for future space development.

Compiler: Nandu reporter Shi Minglei