Importance Score: 85 / 100 🟢
The imminent surge in crewed operations within Low Earth Orbit (LEO) faces a significant threat from escalating space debris, which endangers missions and jeopardizes astronaut safety.
With the International Space Station (ISS) scheduled to retire by 2030, private space stations are stepping in to fill the void. Projects like Starlab, Orbital Reef, Axiom Station, and Haven-1 are preparing to replace the ISS. Concurrently, SpaceX’s Crew Dragon is actively transporting astronauts to the ISS and other locales, with missions such as Fram2 and Axiom Mission 4 showcasing the expanding prospects. Starship might eventually function as an orbital hub for research and development.
Nevertheless, orbital waste will present a formidable obstacle to the next stage of manned space exploration. More than half of all collision threats in LEO are attributable to debris, which encompasses defunct satellites, rocket stages, and smaller fragments resulting from breakups, explosions, and anti-satellite (ASAT) tests. Over the last five years, the ISS has had to execute 14 evasive maneuvers to avoid this debris.
As commercial space stations and manned missions become more prevalent, the chances of a severe collision escalate. Tackling this issue will demand a comprehensive strategy to mitigate hazardous debris, encompassing the prevention of new fragmentation events, reduction of launch-related waste, enhancement of sub-10 centimeter object detection, and the deployment of active debris removal technologies.
The future of human endeavors in LEO hinges on our capability to maintain a secure orbital environment. Without urgent measures, the very infrastructure intended to propel space exploration could evolve into its most perilous hazard.
Strategies to Mitigate Orbital Debris
Preventing Fragmentation Events
Inadvertent satellite breakups persist as a primary source of harmful debris in LEO. Numerous occurrences stem from foreseeable failure modes, including energy system malfunctions, propulsion system breakdowns, and structural wear.
Essentially, these concerns necessitate more rigorous satellite design and operational measures throughout its lifecycle to mitigate the risk of orbital failures.
The top priority is passivation. Although NASA mandates passivation for U.S. missions, operators should adopt more stringent protocols, incorporating autonomous passivation as a safeguard in case of communication loss with ground control. Other initiatives, such as propellant depletion valves, battery disconnect circuitry, and software safeguards to prevent latent energy buildup, should be employed to further diminish fragmentation risks.
Energy system anomalies, particularly battery explosions, remain an under-addressed catalyst for in-orbit fragmentation. Lithium-ion batteries, without adequate insulation, monitoring, and design modification for venting gas, are vulnerable to catastrophic failure. The Defense Meteorological Satellite Program Flight 13 mission underscores how battery rupture events can generate persistent debris fields.
Beyond design enhancements, operators should also focus on lifecycle risk mitigation, encompassing rigorous end-of-life planning, fault analysis, and training for anomaly response. Post-mission disposal verification should be accorded the same significance as launch readiness.
Reducing Launch-Related Debris
Frequent launches constitute another substantial contributor to space debris. As launch activities intensify, stepped-up efforts are needed to ensure these standard missions do not leave perilous objects in orbit.
Inconsistent global protocols enable numerous upper stages to linger in orbit for extended periods. Although U.S. commercial launch providers, particularly SpaceX and Rocket Lab, have enhanced deorbit rates, further progress is essential. 2023 saw The Federal Aviation Administration propose a rule mandating companies to deorbit their launch vehicle upper stages within 25 years. However, a more expedient deorbit timeline of five years or less is imperative to significantly enhance orbital safety. It is also vital for other nations, notably China, Russia, the European Space Agency, Japan, and India, to adopt more stringent measures to curtail upper-stage debris. China’s megaconstellation launches are particularly worrisome, as neglecting upper stages at orbital altitude could heighten collision risks for over a century.
Launch providers should ensure upper stages are passivated to avert explosions and that components disintegrate completely upon reentry. Deployment systems should be engineered to minimize the release of secondary debris, such as bolts and covers. Sharing detailed orbital decay predictions and post-mission disposal telemetry is also crucial for enhancing space traffic coordination and transparency.
Enhancing Detection of Small Debris
Tracking debris smaller than 10 centimeters with current radar and optical sensors proves challenging. This uncertainty impacts space operations, given the millions of such objects in orbit.
At typical orbital speeds around 7.8 kilometers per second, these small objects can inflict substantial damage in a collision. Objects just below 10 centimeters, weighing approximately 0.5 kilograms, carry kinetic energy akin to 3.5 kilograms of TNT, posing risks to pressurized modules and orbital human habitats. Even smaller fragments can be highly destructive. A single centimeter fragment, weighing around 10 grams, can possess energy equivalent to a hand grenade and may compromise exposed equipment. In 2016, an object estimated at a few thousandths of a millimeter caused a notable chip in the ISS’s Cupola module window.
Several endeavors aim to bolster our small debris tracking capabilities. Ground-based radar networks are beginning to enhance sensitivity but encounter difficulties detecting sub-10 centimeter debris, especially at high inclination orbits. Optical tracking stations, capable of prolonged exposure imaging and multi-angle triangulation, are also being developed, although deployment remains limited. Greater emphasis should be placed on advancing in-situ observation sensors and algorithms for detecting and maintaining surveillance of small debris objects.
Accelerating investment and cooperation in these initiatives is pivotal to reducing uncertainty, enhancing catalog completeness, and improving collision risk prediction.
Initiating Robotic Cleanup Efforts
More than 3,000 defunct satellites and over 2,000 rocket bodies remain in Earth’s orbit, many large enough to induce catastrophic collisions.
Active Debris Removal (ADR) technologies must transcend demonstration to functional deployment. Capture mechanisms such as net systems, robotic arms, and magnetic docking technologies have attained Technology Readiness Level 6+ in various programs. Astroscale’s ELSA-d, NASA’s Active Debris Removal Vehicle (ADRV), and ESA’s ClearSpace-1 exemplify potential targeted debris rendezvous and removal.
The U.S. government should incentivize procurement for missions aimed at removing high-risk debris or testing ADR platforms in orbit. A “debris-as-a-service” model, subsidized by NASA or the Space Force, could address commercial viability challenges.
Entering a new phase of orbital activity, crewed operations will be constrained by deteriorating conditions unless drastic measures are implemented. Uncontrolled debris triggers tens of thousands of daily conjunction events in Earth’s orbit, many necessitating evasive maneuvers. Within a typical 72-hour period, the ISS encounters half a dozen conjunction events within its 200-kilometer safety zone.
Without targeted action, routine activities around commercial space stations, research platforms, and transport vehicles will become increasingly intricate and dangerous.