Recently the term Space Situational Awareness (SSA) and Space Traffic Management (STM) has been doing rounds in the news. Some news snippet:

“at the 15th European Space Conference Jan. 25, representatives from the European Commission, European Space Agency and industry said they were making progress in building up European abilities in space situational awareness (SSA) and space traffic management (STM), reducing reliance on the United States.”

“Indian Space Research Organisation (ISRO) wants to develop capabilities in the domain of space situational awareness (SSA) and space traffic management (STM), said chairman of the space agency S Somanath”

A depiction of space debris in Earth orbit. Credit: The Space Foundation

Space Situational Awareness (SSA) refers to the knowledge of the space environment, including location and function of space objects and space weather phenomena. SSA is generally understood as covering three main areas:

  • Space Surveillance and Tracking (SST) of man-made objects.
  • Space WEather (SWE) monitoring and forecast.
  • Near-Earth Objects (NEO) monitoring (only natural space objects).

An SST system is a network of ground-based and space-based sensors capable of surveying and tracking space objects, together with processing capabilities aiming to provide data, information and services on space objects that orbit around the Earth. The main aim is to monitor hazards from space, determine their risk, make this data available to the appropriate authorities and where possible, mitigate the threat.

A defunct Russian satellite and rocket body nearly collided in low Earth orbit Jan. 27, according to LeoLabs. The company is one of several providing commercial space traffic management services as the Office of Space Commerce works to define the basic service it will provide free of charge. Credit: LeoLabs

Space Traffic Management (STM) is defined by the International Academy of Astronautics (IAA) as “the set of technical and regulatory provisions for promoting safe access into outer space, operations in outer space and return from outer space to Earth free from physical or radio-frequency interference.”

Space traffic includes launch vehicles, as well as orbiting objects such as satellites of all sizes and the International Space Station. Space debris risk mitigation is major concern, due to the fact that collision with space debris can destroy vehicles and other space assets. The STM system is critical for ensuring that the expanding orbital population operates safely and efficiently, avoiding collisions and radio-frequency interference while still facilitating widespread space operations in an increasingly congested space environment.

In short, SSA relates primarily to learning about the space environment, including location of space objects, while STM focuses primarily on making decisions based on that information to improve safety of space operations. The two concepts are clearly interrelated, and the latter cannot be done without the good knowledge of the former.

In our next part of this 2-part series we will describe the technologies and methodologies used for SSA and STM.

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