Since the dawn of the Space Age in 1957, the number of human-made objects in Earth orbit has grown exponentially as more satellites, spent rocket stages, and other materials have been left in space following missions. According to official estimates, there are around 34,000 pieces of debris larger than 10 cm currently in orbit. However, the true number of objects both tracked and untracked is likely much higher when you consider debris and objects smaller than 10 cm. This large and growing amount of orbital clutter poses risks both to operational spacecraft and to any future plans for human exploration and industrial development beyond Earth. With more actors than ever launching satellites and performing missions, ensuring safety of flight and preventing collisions that could generate even more debris has become a top priority.

Tracking and Cataloguing Orbital Objects

A key aspect of improving safety and sustainability of space activities is boosting global Global Space Situational Awareness (SSA) capabilities. At its core, Space Situational Awareness (SSA) involves consistently monitoring objects in orbit, carefully tracking their locations and movements, and maintaining accurate catalogs of observational data. Currently the United States Space Surveillance Network is the most advanced entity for SSA, but other nations like Russia, France, Germany, Japan, India and China are also developing independent tracking networks. International data sharing on object locations helps provide a more comprehensive picture, but jurisdictional gaps remain. Commercial enterprises are also scaling up their abilities to observe low Earth orbit and provide specialized services. The challenge lies in integrating systems, standards and policies across military, civilian and commercial domains on a global scale.

Challenges of Tracking Smaller Debris

While objects 10 cm and larger can currently be reasonably well tracked, debris and fragments smaller than 10 cm represent the vast majority of the millions of pieces in orbit. These tiny but still hazardous objects are extremely difficult to detect and monitor due to limitations in current ground- and space-based sensor capabilities. Radar systems struggle to differentiate small debris from natural noise, and visual sensors have resolutions too coarse to reliably image millimeter-sized debris. Techniques like debris laser ranging hold promise but remain prototypes. Without robust tracking of sub-10 cm debris, collision avoidance is mostly reactive rather than proactive. Improving observation of smaller debris through next-generation radars, laser ranging payload deployments, and innovative new sensing methods will be critical to gain a holistic understanding of the changing near-Earth space environment. International collaboration will likewise be needed to optimize limited tracking resources.

Coordination of the Diverse Space Operations Environment

In addition to tracking debris of all sizes, fully realizing the goal of safe and sustainable space operations requires comprehending the complex interactions between myriad operational spacecraft, planned missions, and uncooperative objects. Low Earth orbit in particular is becoming increasingly congested as mega-constellations of hundreds or even thousands of satellites are launched. Coordinating maneuvers, conjunction assessments, and collision avoidance among such dense populations of cooperative spacecraft presents immense logistical and computational difficulties. This is exacerbated further by the need to consider defunct but potentially hazardous objects along with active spacecraft from government, commercial and other non-traditional actors that may not follow established norms. Developing protocols and standards to facilitate information exchange between operators while preserving proprietary and national security sensitivities will be an ongoing challenge.

The Role of On-Orbit Inspections and Services

One promising avenue for enhancing understanding of orbital dynamics as well as mitigating the growth of debris is deploying dedicated inspection and servicing satellites. These space robots could rendezvous with dysfunctional or derelict satellites to gather close-up observations and material samples not possible from ground sensors. In some cases repair or refueling of valuable assets may even be achievable to extend missions. Space Situational Awareness (SSA) data could also be directly collected and downlinked. Commercial firms are prototyping such ambitious capabilities which may one day be deployed en masse to systematically survey the orbital environment. However, on-orbit proximity operations introduce technical complexity and safety risks that will need extensive vetting and standards development to realize the potential SSA and debris management benefits.

International Cooperation is Key to Global Progress

Considering the inherent difficulties of the Space Situational Awareness (SSA) problem along with its importance to all spacefaring nations and stakeholders, boosted international cooperation will be essential to make meaningful strides. While certain military and intelligence data will understandably remain restricted, greater transparency on basic orbital element data and conjunction predictions for all operational entities would significantly help global coordination efforts. International forums like the UN Committee on the Peaceful Uses of Outer Space provide a platform for establishing non-binding best practices, data sharing standards and future governance arrangements. Bilateral partnerships between technologically advanced space agencies can also advance joint SSA capabilities development. Commercial data sources present opportunities for public-private intelligence integration models. Ultimately developing a shared comprehensive understanding of near-Earth space traffic conditions will require aggregating diverse sensing networks and datasets on a collaborative global scale.

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