Amir Gohardani astutely observed that space debris might be approached as waste management and epidemics [“Adopting a New Viewpoint about Orbital Debris,” Commentary, April 28, page 15]. The similarities are more profound than he stated.
Two dramatic similarities have escaped attention: that physical systems seek equilibrium and that humankind inevitably diminishes its environment.
Debris in near-Earth space and beyond is a natural phenomenon. Mankind adds to the population but does not necessarily unbalance it. Even as we launch more and more satellites, a balance will evolve between debris creation and new objects through collisions, re-entry and other dissipative mechanisms. The new state may evolve over decades or centuries, and the equilibrium achieved could be unacceptable if we continue to pollute without constraint.
We can influence evolution to favor acceptable circumstances with well-considered mitigations, but we might not be able to restore the initial state we enjoyed. This is a fundamental precept of ecological resilience and sustainability. It applies well to space debris.
Recent papers and research identify measures that could lead to an acceptable balance by controlling launch rates, choosing carefully in what orbits we place satellites, and distributing well the sizes or cross-sections of satellites. Current practice might lead to an acceptable balance, albeit with more debris. Modest accommodations will not compromise the productivity of near-Earth space.
Active debris removal can mitigate current risk at acceptable cost, but as long as we launch 100 or more large satellites annually from a few launch sites (and hundreds more small satellites from almost anywhere), removing a handful will not have an effect commensurate with cost.
One cannot prove why something did not happen. We cannot claim that any maneuvers saved any satellites. Our threshold of concern is low, and it is usually 99.99 percent more probable that a conjunction of concern would not have evolved into a collision. Prudent resilience and sustainability practices, as pioneered by other ecological disturbances, would be well advised.
David Finkleman
Colorado Springs, Colorado
