Aeronautics is the science or art involved with the study, design, and manufacturing of air flight–capable machines, and the techniques of operating aircraft and rockets within the atmosphere. Aeronautical engineers work with aircraft. They are involved primarily in designing aircraft and propulsion systems and in studying the aerodynamic performance of aircraft and construction materials. They work with the theory, technology, and practice of flight within the Earth's atmosphere. Aerospace is the human effort in science, engineering, and business to fly in the atmosphere of Earth and surrounding space. Aerospace organizations research, design, manufacture, operate, or maintain aircraft or spacecraft. Aerospace Engineers design and test missiles, aircraft, satellites, and spacecraft . They also create propulsion systems and evaluate the aerodynamic performance of aircrafts and assure all blueprints, prototypes, and products meet required engineering standards, environmental issues, and customer requirements. the branch of engineering that deals with the design, development, testing, and production of aircraft and related systems (aeronautical engineering) and of spacecraft, missiles, rocket-propulsion systems, and other equipment operating beyond the earth's atmosphere.