The UN Guidelines for the Long-term Sustainability of Outer Space Activities recognize that “The Earth’s orbital space environment constitutes a finite resource”. Yet, we see limited discussion on how this finite resource is managed and more importantly (given its finite nature) how much of its capacity is currently consumed. 

Orbits, by definition common pool resources, face the problem of congestion as they are universally accessible, not excludable, and rivalrous in consumption. Reflecting on Ostrom’s first principle for managing a commons (i.e. defining the boundaries of the CPR and of those authorized to use it) the unprecedented deployment of space objects in Low Earth Orbit (LEO) compels us to raise the question of available capacity within the LEO environment, with developments at certain orbital altitudes requiring particular attention. 

Despite notable specificities of orbital environments, the reality of operations is bound by similar limits as other traffic regimes, whereby traffic density has an inherent upper limit that still allows for safe management and coordination. As more and more satellites share orbital environments, it naturally leads to an increase in conjunction warnings, which in turn increases the aggregate risk for collisions, further worsening the risk levels for all actors sharing adjacent orbital environments. 

In September 2021 the United Nations Secretary General reported on persistent calls by member states to strengthen the governance of global commons. If there is indeed political will for ensuring that the Earth’s orbital environment remains safe and sustainable, we must avoid a situation where the orbital environment would be either destroyed or monopolized by a few actors.

To ensure sustainability, we don’t necessarily need better (or more) data as often suggested – while crucial for the initial identification of phenomena, data itself does not compel individual actors to utilize the resource in line with Pareto optimal. 

A quantitative metric focused on the available and consumed capacity in the Earth’s orbital environment, would allow us to contextualize the data and comprehend the extent to which our behaviour in this environment is (or isn’t) sustainable. Developing and agreeing on shared metrics represents a crucial enabler for setting up institutions or mechanisms to foster cooperative behaviour – a precondition for the long-term survival of any common pool resource.