Space Traffic Control Architecture

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The flight paths of low-orbiting satellites, on the other hand, are not coordinated and the selection of orbits is not centrally controlled by any international agency. This situation has evolved, at least in part, because near-Earth space is thought to be “big.” In fact, it is big. But, the concept of “big” is only valid as long as the density of things in a given region is extremely low.
The number of organizations using the near-Earth space environment for applications ranging from exploration to exploitation and national security is impressive and continues to grow. Safety is a prime concern for both equipment and personnel. For government operators, the control of risk is mandatory.
For commercial operators, operational efficiency and favorable cost/benefit considerations are paramount. In recent years several government agencies have been studying space traffic management, i.e., regulation of orbital traffic. To date, there has been little control over what is placed into orbit. Each space-faring nation is able to operate independently and with little, if any, international coordination.
This is quite different from the international air traffic management system that allows the free-flow of airline traffic over a major part of the world. Every airliner uses designated airspace that is protected during its flight by air traffic controllers.
Most airliners travel at comparable speeds and collisions are avoided by horizontal and vertical separation standards. This ensures that mid-air collisions are, indeed, rare.
The flight paths of low-orbiting satellites, on the other hand, are not coordinated and the selection of orbits is not centrally controlled by any international agency. This situation has evolved, at least in part, because near-Earth space is thought to be “big.” In fact, it is big. But, the concept of “big” is only valid as long as the density of things in a given region is extremely low.
As the number of satellites and debris objects continue to grow the concept of “big” begins to shrink. In addition, objects in low orbits are all travelling at speeds between 7 and 8 km/sec. Unlike aircraft, satellite and object separations are not controlled.
At any given point in near-Earth space, objects can be flying in every direction. It is entirely possible for a head-on collision to occur, with relative closing speeds of up to 15 km/sec. The continued increase of traffic in these orbits leads one to quickly conclude that space traffic management will soon be necessary in order to sustain the viability of many current space applications.
The management of space traffic is a daunting challenge. At the moment, we lack much of the required technology, there is little international cooperation or collaboration regarding space traffic planning, and the political environment is not amenable to creating a space traffic control architecture. We lack the ability to accurately track and predict the precise movement of satellites and large debris objects.
The location, size and movement of most debris objects are not known. Finally, most things in orbit are not controllable or maneuverable. Many satellites are used for national security and their orbits are classified. Yet, they are intermingled with civil and commercial satellites. Add to this situation issues of national sovereignty and sensitivity and we quickly get into some nasty legal and policy arguments.
It is easy to conclude that any meaningful space traffic control architecture may still be decades away.