The year 2025 brought an alarming orbital emergency, a stark reminder of the growing threat posed by space debris. Our planet is encircled by an ever-increasing amount of human-made junk, and the situation is only getting worse.
Space debris experts estimate that nearly 130 million pieces of orbital waste are hurtling around Earth at high speeds. This includes remnants from rocket explosions, abandoned satellites, and even small fragments from space hardware deployments. What's more, some of this mess is a direct result of anti-satellite weapon testing, where spacecraft are deliberately demolished.
The presence of this space clutter significantly increases the risk of collisions, leading to a chain reaction known as the Kessler syndrome. This phenomenon was first described by NASA scientists Donald Kessler and Burton Cour-Palais in their groundbreaking 1978 paper. Despite their warning, the problem has escalated over the years, and recent debris strike incidents highlight our inability to effectively address or even slow down the accumulation of orbital debris.
One such incident occurred in November 2025, when China's Shenzhou-20 astronauts discovered tiny cracks in their spacecraft's viewport window. The cause was attributed to an impact from space debris, rendering the craft unsafe for the crew's return. This led to the first emergency launch mission in China's human spaceflight program, with an uncrewed Shenzhou-22 spaceship carrying cargo being launched on November 25.
Fortunately, the Shenzhou saga had a positive outcome, with the Chinese astronauts safely returning to Earth aboard the Shenzhou-21 spacecraft. However, Moriba Jah, a space debris expert and professor at the University of Texas at Austin, emphasized that the Shenzhou-20 landing delay is more than just a procedural note. It serves as a warning sign about the state of our orbital commons.
Jah explained that the decision to postpone the crew's return due to a compromised spacecraft window reflects responsible risk management based on incomplete knowledge. It also reveals a deeper issue - our collective inability to maintain a continuous and verifiable understanding of what's moving through orbit. Every fragment we leave in space, Jah said, contributes to a rising tide of uncertainty.
This uncertainty is not just statistical; it's epistemic, Jah argued. When the rate of uncertainty growth surpasses the rate of knowledge renewal, safety margins deteriorate. Jah advocated for the design of missions, governance frameworks, and information systems that can regenerate knowledge faster than it decays.
The cracked window of the Shenzhou-20 spacecraft, according to Jah, is a result of gaps in global tracking, attribution, and accountability. Until nations and companies prioritize data fidelity and transparency as part of safety engineering, similar near-misses will continue to occur.
China's decision to delay the Shenzhou-piloted vessel's re-entry until engineers were confident in their assessment was an act of epistemic humility, Jah noted. It recognized the unknown and adjusted accordingly. Such humility, he said, should be the norm, not an exception.
In Jah's view, the Shenzhou-20 episode should prompt the international community to embrace auditable stewardship. This includes establishing common baselines for orbital situational awareness, interoperable knowledge graphs, and certification programs that recognize missions that restore order rather than add risk.
"Only by aligning engineering, policy, and information ethics can we prevent 'routine' anomalies from becoming precursors to catastrophe," Jah said. "If we learn the right lesson, this will not be remembered as a lucky escape but as a turning point." He added that it's crucial to understand that safety in orbit begins with honesty about what we know and don't know, and with the will to regenerate knowledge faster than we lose it.
Darren McKnight, a senior technical fellow at LeoLabs, a group dedicated to space domain awareness, highlighted two major issues in 2025. The first was the proliferation of satellite constellations, some responsibly managed like Starlink, Iridium, and OneWeb, and others poorly managed like China's "Thousand Sails" megaconstellation and its "Guowang" satellite internet payloads. The second issue was the abandonment of rocket bodies in orbits that will linger for more than 25 years. While there is potential for a 30% reduction in debris-generating potential in low Earth orbit by removing the top 10 statistically concerning objects, the global community is leaving rocket bodies at an accelerating rate, ignoring the known long-term negative effects.
"Some operators in low Earth orbit are ignoring known long-term effects of behavior for short-term gain," McKnight said, drawing a parallel to the early stages of global warming. "Some will not change behavior until something bad happens."
The United Nations Environment Program (UNEP) has also raised concerns, releasing a document titled "Safeguarding Space: Environmental Issues, Risks, and Responsibilities." The document identifies a set of space debris woes as "emerging issues," highlighting the exponential growth of the space sector and the resulting environmental challenges at all layers of the atmosphere.
The UNEP specifically flagged air pollution from launch emissions, spacecraft emissions in the stratosphere, and space debris re-entry, which has the potential to alter Earth's atmospheric chemistry and dynamics, with implications for climate change and depleting stratospheric ozone.
"A multilateral, interdisciplinary approach is needed to better understand the risks and impacts and how to balance them with the essential daily services and benefits that space activity brings to humanity," the UNEP document concludes.
