Pleiades Fractionated Space System Architecture and the Future of National Security Space

Abstract

In recent years, national security space systems have been plagued by cost overruns, schedule slips, and requirements creep. Notable programs have received much coverage in the press after incurring multiple Nunn-McCurdy cost growth breaches (total program cost increase by greater than 25%) or being cancelled outright. While these programs are the most visible, they are merely examples of the widespread problems with the government’s and industry’s approach to military space. While a spacecraft that is never launched obviously provides a poor return on government investment, those spacecraft that have reached orbit may be equally bad investments if mission needs have changed or a critical component fails soon after launch. Recent studies suggest that fractionated space systems can produce a higher value return on investment than traditional monolithic systems. Rather than continuing to design large monolithic satellites with unrealizable and competing requirements for performance and lifetime, we plan to develop a fractionated space system architecture, informed by value-centric engineering, that enables rapid initial operational capability through staged deployment, flexibility to changing national security needs, and robustness against attack and failures. The Pleiades architecture implements fractionated space systems, where the system’s functionality is spread over multiple, heterogeneous spacecraft modules. Each spacecraft module is a free-flying entity that has its own set of typical spacecraft bus functions but carries a unique mission payload or a resource such as a mission data processor, solid state recorder or high bandwidth downlink. The spacecraft modules fly in a cluster, and communicate with each other through a shared wireless network. The Pleiades architecture allows for rapid response to operational needs, whether it be by launching new spacecraft modules to join a cluster or by retasking existing spacecraft resources. Modules carrying new payloads or resources are produced more quickly and at lower cost than traditional systems by using commercial space best practices, single string designs (system reliability is achieved through redundancy across spacecraft modules), and the benefits of economies of scale. This can lower the barrier to deploying space-based assets for agencies that cannot currently afford them. Also, the cluster is less vulnerable to attack, and can disperse itself when there is an incoming threat. When a failure does happen, the architecture provides for a smooth degradation in capability until a replacement can be launched and brought in to the cluster. The fundamental innovation of this architecture is that information integration, not physical decomposition, is the key to realizing fractionation. In current space systems, the main inhibitor to rapid evolution and adaptation is stovepiped architectures that inhibit movement of information between elements, including the ground, and prevent reconfiguration of information flow to meet evolving mission needs. A fractionated space