Operating missions include missions at the start of the Operations and Sustainmentphase of their life-cycle. This phase marks the transition from system development and acquisition activities to primarily systems operations and sustainment activities.
Missions under development are missions that are at the Final Design and Fabrication(Phase C) and System Assembly, Integration and Test, and Launch (Phase D) phases of their life-cycle. The primary activities in this category are developmental in nature, including acquisition contract execution. Phase C includes: the completion of final system design and fabrication of test and flight architecture; qualification testing; development of detailed integration plans and procedures; and test of components, assemblies, and subsystems. Phase D entails: system assembly, integration, and test (AI&T); verification/ certification; prelaunch activities; system launch; and completion of on orbit checkout or initial operations.
Under study missions include missions that are at the pre-formulation and formulation stages of their life-cycle. Pre-formulation begins the process to define a viable and affordable concept for new NASA programs and projects, via concept studies. This step is followed by the formulation stage, which consists of two sequential phases, the Concept & Technology Development phase and the Preliminary Design & Technology Completion phase. The primary activities in these phases are to develop and define the project requirements and cost/schedule basis, and to design a plan for implementation (including an acquisition strategy, contractor selection, and long-lead procurement).
Past missions are missions that have reached the Closeout phase, during which project systems are taken out of service and safely disposed, although scientific and other analyses might still continue under project funding.