The definition of SSA can mean different things depending on context. The European Space Agency (ESA) defines SSA as consisting of three distinct segments:
- Space weather (SWE): providing timely and accurate information that supports mitigation of the adverse impacts of space weather.
- Near-Earth objects (NEO): observing NEOs, predicting their orbits, producing impact warnings and when necessary involvement in potential mitigation measures.
- Space surveillance and tracking (SST): detecting space debris, cataloguing debris objects and determining and predicting their orbits.
The Space Foundation defines SSA as ‘the ability to view, understand and predict the physical location of natural and manmade objects in orbits around the Earth, with the objective of avoiding collisions’. This is an example of limiting SSA to cover those activities more accurately defined as STM. As defined by US Space Policy Directive-3, STM ‘… [means] the planning, coordination, and on-orbit synchronization of activities to enhance the safety, stability, and sustainability of operations in the space environment’. STM activities include tracking active satellites as well as the millions of pieces of debris that are found in orbit, providing data for satellite operators, and preventing collisions that could damage or destroy satellites and cause an increase in debris. While these are in no doubt essential activities for ensuring the sustainability of orbits, they do not cover all the information that is required for a full understanding of the space environment close to Earth and the most frequently used orbits.
SSA is dependent upon surveillance, environmental monitoring, domain analysis, and the status of US satellites and readiness, as well as the importance of understanding the space capabilities and intent of those who may pose a threat.
In its broadest form, SSA refers to knowledge of the near-Earth orbit environment, particularly activities in and phenomena affecting orbits that host space assets upon which much of defence and civil operations depend. This paper has adopted this broad definition as it provides the widest range of opportunities for increased European capabilities and potential cooperation with the US. The US military’s Joint Publication 3-14 Space Operations summarized this broad definition as: ‘SSA is the requisite foundational, current and predictive knowledge and characterization of objects and the OE [Operational Environment] upon which space operations depend – including physical, virtual, information and human dimensions – as well as all factors, activities, and events of all entities conducting, or preparing to conduct, space operations’. This definition notes that SSA is dependent upon surveillance, environmental monitoring, domain analysis, and the status of US satellites and readiness, as well as the importance of understanding the space capabilities and intent of those who may pose a threat.
Although in one sense SSA began with the launch of Sputnik in 1957, when both the US and USSR were attempting to understand each other’s intentions in space, the STM aspect took a step forward with the establishment in the US in 1979 of the Space Defense Operations Center (SPADOC), later called the Space Control Center, the work of which now sits within the Combined Space Operations Center (CSpOC) at Vandenberg Air Force Base in California. Because of the nature of early space operations as state activities, and within the geopolitical environment of the Cold War, SSA activities were traditionally performed within a military setting. However, as space has become more democratic with a proliferation in both state and commercial actors, SSA providers have also diversified to meet the demands of operators. As well as more countries developing indigenous SSA capabilities, commercial companies now also work to provide essential information to satellite operators.