The Growing Challenge of Orbital Debris: Engineering Solutions for a Sustainable Space Environment

A crisis has been quietly brewing for decades in the vast expanse above our planet. The orbital regions surrounding Earth, particularly low-Earth orbit (LEO), have become increasingly congested with human-made objects—from operational satellites providing essential services to defunct spacecraft, discarded rocket stages, and fragments from collisions and explosions. As we launch more satellites to meet our global communication, observation, and scientific needs, the risk of collisions and the creation of additional debris escalates, potentially threatening future access to space.

The Scale of the Problem

Since the launch of Sputnik in 1957, humans have placed thousands of satellites into orbit. As of early 2025, more than 7,500 operational satellites circle the Earth, with commercial satellite constellations like Starlink accounting for a significant portion. However, these functioning satellites represent only a small percentage of tracked objects.

The U.S. Space Surveillance Network tracks approximately 27,000 pieces of orbital debris larger than 10 cm. Beyond these trackable objects lie an estimated 900,000 objects between 1-10 cm and tens of millions smaller than 1 cm. Even these tiny fragments pose significant threats—travelling at orbital velocities of approximately 7-8 km/s, a collision with an object as small as 1 cm can damage or turn off a satellite, while impacts with larger debris can be catastrophic.

The problem is self-perpetuating. In 2007, China conducted an anti-satellite missile test, destroying one of its weather satellites and creating over 3,000 trackable debris fragments. Two years later, a defunct Russian Cosmos satellite collided with an operational Iridium communications satellite, generating another 2,000 trackable pieces of debris. These two events alone increased the trackable debris population by nearly 40%.

The Kessler Syndrome, theorized by NASA scientist Donald J. Kessler in 1978, describes a scenario where the density of objects in LEO becomes high enough that collisions between objects could cause a cascade—each collision generating debris that increases the likelihood of further collisions. This runaway chain reaction could render specific orbital ranges unusable for generations.

Engineering Challenges of Debris Removal

The technical challenges facing engineers attempting to solve the orbital debris problem are formidable:

Before anything can be removed, it must be precisely located and identified. This requires:

• Advanced radar systems capable of detecting small objects at orbital distances
• Optical tracking systems for higher orbits
• Complex algorithms to process sensor data and maintain a catalog of objects
• Predictive models to forecast orbital paths and potential conjunctions

Engineering teams must develop systems that can distinguish between different types of debris, assess their tumbling rates, and determine their physical characteristics—all essential information for planning a removal operation.

Approaching an uncooperative, potentially tumbling object in orbit presents significant challenges:

• Precise orbital mechanics calculations for fuel-efficient intercept trajectories
• Real-time sensing and navigation systems capable of operating in the harsh space environment
• Autonomous decision-making algorithms for final approach phases
• Collision avoidance protocols to prevent the remediation mission from creating more debris

These operations require engineering solutions that combine spacecraft propulsion, sensor fusion, and artificial intelligence systems capable of making split-second adjustments.

Once a debris object is reached, it must be securely captured without creating additional fragments. Engineers have developed several approaches:

• Robotic arms with specialized gripping mechanisms
• Net-based capture systems for tumbling objects
• Harpoon-like devices for robust attachment points
• Electromagnetic systems for metallic debris
• Adhesive or tether-based solutions

Each approach requires extensive testing on Earth and space-like conditions to ensure reliability. Material scientists must develop components that can withstand the space environment’s extreme temperature variations and radiation exposure while maintaining their mechanical properties.

After capture, debris must be removed from crowded orbital regions:

• For objects in LEO, controlled re-entry into Earth’s atmosphere (requiring precise trajectory control to ensure burn-up over unpopulated areas)
• Objects in higher orbits transfer to “graveyard orbits”, where they pose minimal risk.

These manoeuvres demand sophisticated propulsion systems, thermal protection for re-entry, and careful mission planning to minimize risks to ground populations and other space assets.

ClearSpace’s CLEAR mission represents one of the most advanced attempts to address these challenges. Their engineering approach incorporates several innovative elements:

The ClearSpace servicer spacecraft employs a modular architecture that allows for:

• Separation of critical subsystems to enhance reliability
• Radiation-hardened computing systems for operating in the LEO environment
• Redundant propulsion and power systems to ensure mission completion

This modular approach enables iterative improvements in future missions based on operational experience gained during initial debris removal operations.

Successful debris removal relies heavily on accurate sensing capabilities. ClearSpace’s system incorporates:

• Multi-spectral optical sensors for visual tracking and identification
• Custom-developed image processing algorithms that can differentiate between debris objects and the Earth or space background
• Lidar systems for precise distance and orientation measurements
• Radar technology developed with Plextek specifically for rendezvous and proximity operations

These sensors must function reliably despite challenging lighting conditions, reflection issues, and the potential for equipment degradation in the space environment.

At the heart of the ClearSpace approach is its innovative capture system:

• A four-armed robotic mechanism capable of adapting to differently shaped objects
• Computer vision-guided grasping algorithms
• Force-feedback systems to regulate grip pressure and prevent fragmentation
• Mechanical damping to absorb the kinetic energy of tumbling debris

The robotic system underwent rigorous testing to ensure it could withstand launch loads—experiencing forces several times Earth’s gravity—while remaining precise enough to handle delicate operations in orbit.

Due to communication delays and limited windows for ground control, significant portions of the mission must be performed autonomously:

• Real-time trajectory planning algorithms
• Decision-making systems with fail-safe protocols
• Self-diagnostic capabilities to detect and resolve anomalies
• Machine learning components that improve performance over time

The software architecture, developed with Critical Software using their Karvel Onboard Software Platform, integrates these autonomous functions while maintaining strict safety parameters.

Precision is essential for debris removal operations. ClearSpace’s navigation system includes:

• Star trackers for absolute positioning
• Relative navigation algorithms developed with Indra-Deimos
• Cold gas thrusters for delicate manoeuvring during approach phases
• Collision avoidance systems that continuously recalculate safety margins

These systems must perform reliably in an environment where GPS is unavailable and visual references change constantly due to orbital movement and lighting conditions.

The Role of Engineers in Solving the Debris Problem

The orbital debris challenge exemplifies the complex, multidisciplinary problems that modern engineers must tackle. Several engineering disciplines converge to create viable solutions:

Aerospace Engineering

Aerospace engineers design the spacecraft structures, propulsion systems, and thermal control mechanisms essential for debris removal missions. They must balance competing requirements, including:

• Structural integrity to withstand launch and orbital manoeuvres
• Mass optimization to minimize launch costs
• Thermal management in the extreme temperature environment of space
• Radiation tolerance for electronic components

The structural testing performed by Spirit AeroSystems during ClearSpace’s Phase 2 reflects this critical aspect of mission development.

Robotics and Mechatronics

The capture of uncooperative objects in space represents one of the most challenging applications of robotics:

• Developing mechanisms that function reliably in vacuum conditions
• Creating end effectors capable of adapting to various shapes and surfaces
• Implementing control systems that can manage the complex dynamics of two free-floating bodies
• Ensuring mechanical reliability despite extreme temperature variations

Robotics engineers must address these challenges within strict mass and power budgets.

Software and AI Engineering

Software forms the backbone of modern space missions, with debris removal requiring particularly sophisticated systems:

• Computer vision algorithms for object detection and tracking
• Guidance, navigation, and control software for precise manoeuvring
• Autonomous decision-making systems for time-critical operations
• Fault detection, isolation, and recovery systems to ensure mission continuity

Critical Software’s work on ClearSpace’s flight software demonstrates the essential role of software engineering in enabling complex space operations.

Systems Engineering

Perhaps most importantly, systems engineers integrate these diverse technologies into a coherent, reliable mission architecture:

• Defining interfaces between subsystems
• Establishing verification and validation procedures
• Managing technical risks across the entire mission profile
• Ensuring regulatory compliance and mission safety

The successful completion of ClearSpace’s Phase 2 milestone reflects effective systems engineering practices that brought contributions from multiple partners into a cohesive design.

While engineering solutions are essential, addressing the orbital debris problem comprehensively requires complementary policy and economic frameworks. No single nation can solve the debris problem alone, so engineers must work within international frameworks that facilitate the work.

Of course, prevention remains more cost-effective than fixing the problem after it occurs. Engineers are already implementing design approaches that minimize future debris:

• Passivation systems to deplete onboard energy sources at end-of-life
• Drag enhancement devices to accelerate orbital decay
• Design-for-demise principles to ensure complete burn-up during re-entry
• Standardized grappling fixtures on new satellites to facilitate future removal if necessary

If the CLEAR mission succeeds, it will represent a technical achievement and a paradigm shift in how we approach space operations—moving from a “launch and forget” model to sustainable, responsible stewardship of the orbital environment.

Today’s engineers working on debris removal are pioneering techniques that will become standard practice in future decades, ensuring that access to space remains available for generations. Their work exemplifies how engineering can address humanity’s most complex challenges, combining cutting-edge technology with environmental responsibility and international cooperation.

As we continue to rely on space-based infrastructure for communications, navigation, Earth observation, and scientific discovery, the importance of these engineering efforts will only grow. The orbital debris problem presents a crisis and an opportunity to demonstrate how human ingenuity can correct past oversights and create a sustainable path to space exploration and utilization.