Aeronautic and space applications require the development of sensors with capabilities beyond those of commercially available sensors. This chapter reviews a range of aerospace applications and the sensor operational requirements for those applications. These applications include leak detection, high-temperature physical parameter monitoring, emission monitoring, fire/environmental

monitoring, and ultraviolet radiation monitoring. In response to these needs, a range of nanotechnology-based sensor material work is being developed. This includes transition metal silicide nano-wires for physical measurements; palladium nanoshells, ultrathin films, and nanowires for hydrogen detection; semiconducting metal oxide nanostructures relevant to fire/environmental/ emissions monitoring; and modified zinc oxide materials for ultraviolet radiation detection. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. The advent of nano-based sensor materials can have notable effect on aerospace applications. However, these materials must be integrated into complete sensor systems and these advantages must be demonstrated for the specific application.