The European Space Agency’s (ESA) Sixth European Conference on Space Debris, a quadrennial event that recently concluded in Darmstadt, Germany, is a bright star of collaboration to sustain productive use of space.
In 1950, Merrill Flood and Melvin Drescher at Rand Corp. formalized the “Prisoner’s Dilemma,” which explains why individuals would not cooperate even when it is in their best interests to work together. Since then the classic differential game has been expanded to include social norms and metanorms, many players and diverse rules of engagement, such as whether players might have some knowledge of how the others respond. The fundamental two-player, non-zero-sum game almost always evolves to the worst outcome for all. However, real or societal penalties for defection and understanding that others are willing to cooperate change the outcome.
The ESA meeting exposed diligent accomplishment in the world’s space community. Virtually all stakeholders contributed, including the United States, Russia, China, Japan, France, Germany, Italy, Poland, the Czech Republic, the United Kingdom, Spain, South Korea and others in every hemisphere from Scandinavia to Argentina, Europe and Asia. All presented their operational concepts and techniques for perceiving dangerous close approaches among satellites, avoiding collisions and mitigating consequences. All emphasized the need for essential orbit and satellite architecture data and information. The consequences of the current data deficit were described and quantified.
The nature of fragmentation and collisional damage and debris production is much better understood than ever but still evolving. Although estimates of the evolution of the near-Earth debris population do not uniformly predict cascading catastrophe, it is unanimous that the rate of increase of debris must be diminished and that action is necessary to mitigate the debris risk to active and productive satellites.
No one should doubt the merits of risk reduction through removal of very large, dead rocket bodies and satellites.
There are many innovative and feasible approaches. Industry and governments should invest in developing hardware and mission architectures. The ESA Clean Space Initiative stands out. Although it was not stated specifically, the French space agency, CNES, and its companion organizations appear to have mature concepts and analysis supporting removing Envisat, which became uncontrollable last year.
The task is much more than grabbing and pushing or pulling. Forces must be applied in the right place and in the right direction, and the descent must not jeopardize other satellites or human activity on the Earth.
Envisat is an excellent subject since its mass properties and dynamics are known, its orbit is well characterized, and there are no salvage rights or serious civil legal complications.
The conference exposed sincere, worldwide concern and capability. It introduced into the adversarial commercial and political environment the factors that have been demonstrated to foster collaboration in decades of Prisoner’s Dilemma research.
The numerous civil, commercial and governmental stakeholders should join the initiative to remove Envisat and to share data and information that the conference proved essential to preserving and enhancing the productive and fragile near-Earth space environment.
David Finkleman is senior scientist in the Center for Space Standards and Innovation at Analytical Graphics Inc. in Colorado Springs, Colo.
