Space Debris Game Theory
In class, we learned of game theory as a situation with two or more players, where each player has a set of actions to choose from. However, the outcome for each player depends on the collective actions of every player, so each player must also take into consideration what every other player is likely to choose when making a decision.
This article applies classical game theory to the task of cleaning up space debris. The reason this is critical is because “a piece of debris just 10cm in diameter could cause an entire spacecraft to disintegrate and it is estimate that there are more than 29,000 objects larger than 10cm in Earth’s orbit” (Tuyls, phys.org). Of course, 29,000 sounds like a terrifying amount but given the size of the earth, it is perhaps not as critical to clean up space debris (yet). The article breaks this problem down into very simple game theory terms: national space agencies and private satellite companies are the players, and their two options are to either remove the debris themselves, or wait for another player to do it, and do nothing themselves. By removing the debris themselves, they equally benefit all players, but if they do nothing and wait for another player, they would get the same benefit, but without the cost to themselves. However, if all players choose to wait for another player to clean it up, the amount of debris will only grow, increasing the likelihood of a catastrophic spaceship collision.
This is known as the tragedy of the commons, where players are acting for their own benefit, instead of thinking of the group collectively. Because each strategy yields the same payoff, but doing nothing is free while cleaning up is expensive, we can assume that doing nothing is a dominant strategy IF there is an assumption that at least one player will clean it up. However, because every player is hoping somebody else will clean it up, this results in a game where all players are doing nothing.
Scientists are now trying to create a simulator using techniques from game theory, to help “design software to design strategic situations and take good decisions without human supervision” (Tuyls, phys.org). An example of this would be the automatic bidder discussed in one of the homeworks. By creating a model of the debris problem, it would be easier to get an idea of how much effort towards cleanup each player would be willing to invest in, as a distinct middle ground between all or nothing.
This is an awesome example of how game theory can be used to solve very real, very important problems. Complex problems such as space debris removal can be generalized to a “game”, following the rules of the theory, and then unique factors can be taken into consideration, to provide an agreeable best-strategy for all players to maximize the benefit.
Link to article: http://phys.org/news/2015-11-space-debris-game-theory.html