A hierarchical approach to the sustainable management of Controlled Ecological Life Support Systems: part 1, an ecological and engineering synthesis.
In this article we present, in an expository manner, an approach to the sustainable management of a Controlled Ecological Life Support System (CELSS) based on concepts from both engineering and ecology. Our perspective leads us to express the sustainability of CELSS in terms of constraints imposed on its subsystems. These constraints are of two types: static and operational. Static constraints capture the basic sustainability requirements of the individual subsystem components--they represent the absolute limits (bounds) on the operating range of these subsystems. Operational constraints, on the other hand, represent a response to global changes in the availability of system resources. They are imposed as the system evolves dynamically to avert shortages or surpluses in resources in various subsystems. As well as having implications on design, our perspective, termed the constraint perspective, leads naturally to a management hierarchy. The second article (this issue) in this series will explore the feasibility of this approach and demonstrate some of its consequences based on a simple CELSS model.