How to clean up space debris – using game theory
A piece of debris just 10cm in diameters will cause an entire spacecraft to disintegrate and it is estimated that there are more than 29,000 objects larger than 10cm in Earth’s orbit. This poses a huge difficulty for spacecrafts and the satellites which are essential to many aspects of daily life such as weather and communication. Although the situation sounds severe enough, no entities—-governments and corporations—- has taken any serious actions so far, since the actions will be very difficult to operate and very costly. The scientists are seeking a feasible strategy to deal with this situation.
The situation described in this article is actually about game theory: the entities are players that get an outcome from their actions. If an entity choose to take an action first, it will be extremely difficult and costly, but for the following entities, it will be much easier. So only concerning for own interests, every entity would choose to wait for other entities to deal with the debris first. But that will make the situation worse and worse, as aging satellites and used rocket launchers are creating more and more debris. As a result, the low-earth orbit space would be not available for everyone, as described in the following payoff matrix:
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which can be described as a “space dilemma”.
What was proposed by the article is to create a realistic computer model of debris removal situations that can be used to perform an analysis using game theory. For example, it could predict the amount of effort each entity would be willing to invest on clean-up given the immediate and long-term risk to their space assets such as satellites. Then it enables us to determine the best strategy to clean up the debris—-the order of entities to take actions, and the proportionate of debris for each entity to clean up.