Q: What is orbital carrying capacity?
A: Orbital carrying capacity is the concept of how much “traffic” a particular orbit can safely hold. This metric is determined by the volume of satellites and space debris that can safely orbit the Earth without increasing the likelihood of collisions past an acceptable level of risk. As the number of satellites increases in near-Earth orbits, an orbital carrying capacity threshold is one important way to help avoid over-crowding and collisions in these orbits.
Q: How is orbital carrying capacity determined?
Determining orbital carrying capacity is complex and not readily available. First, the remaining amount of space will need to be calculated, which will require taking into account factors such as the mass and minimum cross-section of a satellite as well as the number of objects in space. Such calculations would entail an extensive initial effort to collect the necessary data on these factors.
Complicating matters further is the fact that the data is ever-changing and evolving. Collisions in space create radical changes in the orbital environment, where thousands of pieces of space debris can be released all at once and continue to collide with each other. That’s on top of existing space objects and orbital debris. Moreover, new objects are being launched into space all the time.
Finally, the level of risk in space will need to be measured and included in the calculations. The amount of risk humanity is willing to accept can be determined by balancing the positives of what satellites bring to Earth with the potential loss of access to space altogether. Just as we accept a certain level of risk on our highways here on Earth to facilitate mobility, we must also determine what we can tolerate in space.
Q: What happens when orbital carrying capacity is exceeded?
A: The closer an orbit gets to its carrying capacity, the more likely collisions between space objects become. At some point, the chance becomes so great that the entire orbital space can be rendered unusable for decades or longer. The “Kessler Syndrome” is the worst-case scenario where an initial collision creates even more debris that can then collide with other debris and so on and so forth until the near-Earth orbits are completely unusable. Imagine a dense dust cloud surrounding the Earth in which every particle causes devastating destruction.
Q: How are space agencies and sovereign nations applying the concept of orbital carrying capacity?
A: Amid growing concern about orbital crowding worldwide, scientists and regulators are looking at a variety of ways to address the situation. However, there are no recognized or agreed-upon orbital carrying capacity metrics to date.
If orbital environments are to be thought of as a “global common” — i.e., a limited natural resource universally accessible — then quantifying that resource is essential. Internationally agreed-upon orbital carrying capacity parameters can give global regulatory agencies an important tool to coordinate a response to orbital crowding and prevent the Kessler Syndrome from occurring.