A clear distinction is usually appropriate between the technologies and development processes for space–borne and ground–based functions. Limitations in the performance of space–borne computing, storage and dissemination facilities often preclude the use of non–space software technology. The key to affordability is the creation of international standards so that despite relatively high development costs, solutions can be reused across many missions and organizations. By contrast, ground–based functions can benefit from products developed for non–space applications. The challenge is to create an architecture that benefits from existing technology and meets the mission requirements. Optimizing the organizational arrangements for space missions is perhaps where the greatest savings can be made. A management structure that ensures that end users dominate the establishment of requirements leads to more affordable missions than one that is, say, technology driven. Industry implementation teams must include expertise in the scientific disciplines and mission objectives to ensure success. Geostationary–weather–satellite, space–science and satellite–navigation missions are used to illustrate these issues.