The Growing Threat of Space Junk

For six months, astronaut Ron Garan lived and worked on the International Space Station (ISS), experiencing our planet from a vantage point few can imagine. From this perspective, he witnessed the breathtaking beauty of Earth—the glowing Caribbean, the majestic Himalayas, and the diverse landscapes of the Middle East. However, this “God’s eye view” is increasingly overshadowed by a looming danger: space debris.

A History of Space Junk

For nearly 60 years, humanity has launched rockets and spacecraft into Earth’s orbit. The result is a growing cloud of space debris, ranging from tiny screws and bolts to defunct satellites, encircling our planet. This transformation of the space above us into a cosmic junkyard poses a significant threat to ongoing and future space missions.

On February 10, 2009, a stark reminder of this threat occurred. In orbit above Siberia, a Russian military satellite collided with an American communication satellite. Traveling at nearly 36,000 kilometers per hour, the collision created thousands of pieces of debris, adding to the already congested orbital pathways. This was the biggest satellite collision in history and an eye-opening warning about the worsening crisis of space debris. The remnants of this collision remain in orbit, contributing to the millions of human-made objects posing a risk to space activities.

The ISS in the Crosshairs

The ISS, which symbolizes human achievement in space exploration, is now in the crosshairs of this debris. The station has already been struck by small fragments of space junk on several occasions. Although it has survived these minor impacts, there are no guarantees that larger, more destructive collisions won’t occur in the future.

Monitoring this debris is the responsibility of the military, specifically the team at Vandenberg Air Force Base in California. These men and women track approximately 23,000 objects in space, including about 1,300 active payloads or satellites. The rest is space debris from previous launches and collisions. This task is crucial because even a piece of debris as small as a screw can destroy the ISS or other satellites, severely degrading our ability to perform everyday activities reliant on satellite technology, such as ATM withdrawals and GPS navigation.

In June 2011, Ron Garan experienced this danger firsthand. During his mission, a piece of space debris was detected too late for the ISS to change its orbit and avoid a potential collision. The astronauts had no choice but to prepare for the worst, racing to the Soyuz capsules—essentially lifeboats for the ISS crew—and bracing for impact. Fortunately, the debris passed within a football field’s distance of the ISS, but the incident highlighted the ever-present risk posed by space junk.

The Impact of Anti-Satellite Tests

On March 27, 2019, Indian Prime Minister Narendra Modi announced India’s first successful anti-satellite test. A three-stage missile launched from Abdul Kalam Island destroyed the military satellite Microsat-R, creating hundreds of pieces of debris. This test, like others before it, was condemned globally for contributing significantly to the space debris problem. Such political posturing only exacerbates the already critical situation in Earth’s orbit.

Anti-satellite tests aren’t the sole contributors to space debris. Every launch deposits unwanted waste into space, from aluminum-oxide particles from solid-fuel rockets to paint chips and fragments from explosive bolts. Even tiny particles can cause significant damage, as evidenced by the numerous impacts on the Space Shuttle windows during its missions.

The Rising Probability of Collisions

The likelihood of collisions in space is continuously rising. In 2007, the probability of a collision between any satellite in low Earth orbit and a piece of debris over 1 centimeter in size was 17-20% per year. This increased to 25-33% after China conducted an anti-satellite test later that year. By 2010, the chance of a 1-centimeter piece of debris striking a satellite had increased to 50% annually, following the collision between Iridium 33, a US communications satellite, and Kosmos 2251, a retired Russian communications satellite. This collision produced over 1,000 fragments larger than 10 centimeters, creating a dangerous environment for all space missions.

Designing for Safety

To mitigate the risk, space agencies must design satellites capable of withstanding small impacts and dodging larger ones. The ISS, for example, can withstand objects up to 1 centimeter in size and has systems to evade larger, trackable objects. However, objects in the intermediate size range pose a significant threat as they are often untrackable but large enough to cause serious damage.

When the ISS was being planned, NASA established a risk management policy ensuring that the probability of any critical component being penetrated by space debris would be less than 19% over 10 years. Critical components are those whose damage could lead to loss of life, and extensive testing on Earth helps categorize these components and determine appropriate shielding measures.

Innovative Solutions to the Space Junk Problem

Innovative solutions are necessary to address the space junk crisis. One such solution is the ClearSpace-1 mission, set to launch in 2026. This mission involves a robotic claw designed to capture and remove space junk. Developed by researchers in Lausanne, Switzerland, ClearSpace-1 aims to grab a discarded rocket fragment and bring it back to Earth. This mission represents a bold and unexpected approach to tackling the space junk problem. The claw, equipped with machine learning capabilities, will autonomously locate, capture, and deorbit space debris, demonstrating a potential path forward for cleaning up our orbital highways.

Addressing the Problem with Lasers

nasa laser broom for space junk
Credit: NASA

One of the most promising technologies for space debris removal involves the use of lasers. Ground-based and space-based laser systems can be employed to nudge debris into lower orbits, where it can burn up in the Earth’s atmosphere. This method, sometimes referred to as a “laser broom,” was proposed by NASA’s Project Orion in 1996. According to NASA’s 2023 cost and benefit analysis, laser systems are the most cost-effective way to address space debris, especially for objects in the 1 to 10 centimeter range, which are too small to track but large enough to cause significant damage.

International Cooperation and Future Steps

Cleaning up existing space junk is only part of the solution. We must also prevent the creation of new debris. This involves planning the full lifespan of every object sent into space and ensuring it can be safely deorbited at the end of its mission. International cooperation and regulations are essential to enforce these practices, as space is a shared resource under no single country’s jurisdiction.

The European Space Agency’s Zero Debris Charter, announced in June 2023, emphasizes mitigation of space debris – preventing the creation of new debris going forward. By committing to things like designing satellites that reenter Earth’s atmosphere on their own after completing their missions – instead of sitting in space as trash. In the US, the FCC introduced a new five year rule in September 2022 that said US-based spacecraft put into low Earth orbit must de-orbit themselves within five years of mission’s end.

Conclusion

The beauty of Earth from space is a sight worth preserving. To continue exploring and utilizing the space environment safely, we must address the problem of space debris with urgency and ingenuity. The survival of current and future missions, including the ISS, depends on our ability to clean up the space junkyard we’ve created. The time to act is now, before our “God’s eye view” becomes permanently clouded.

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