AbstractThe fundamental concepts and process of systems engineering as they apply in the context of the National Aeronautics and Space Administration are described. In particular: Systems and systems engineering are defined, and the objectives of systems engineering are discussed. The doctrine of successive refinement is presented, and the associated spiral model of the systems engineering process is described. The various phases of the project cycle for major systems acquired by NASA are examined.This paper is based on material being prepared for the first draft of theNASA Systems Engineering Handbook. Consequently, the authors are seeking constructive criticism.