vehicles. Efficient transfer depends significantly on the creation of efficient interfaces between the various modes of the transportation system. Since these interfaces are frequently concerned with handling materials, they also are critically dependent on the progress that results from research on materials. It is also worth noting that the need for control of large amounts of information, often in real time, places increasing demands on the control systems and the computers that support these systems.
From the materials science and engineering perspective, the main materials of interest can be classified according to type and weight. They are (1) bulk materials such as concrete, asphalt, and aggregate, which form the over-whelming percentage of the weight of railbeds and roadbeds; (2) structural metals (primarily steel), which perform critical structural functions in the form of rail tracks, railcars, bridges, ships, pipelines, and concrete reinforcement and in new metal alloys and reinforced plastics that are being used increasingly in aircraft and ground vehicles; and (3) specialized materials such as polymeric materials used for protective clothing, coatings, adhesives, and vehicle interiors and exteriors.
Although the relevant missions of DOT have been categorized as safety and efficiency, these two functions are clearly intertwined. Deterioration, when unchecked, leads either to unsafe conditions or to less than optimal use of infrastructure capacity. Overall evaluation of the needs and opportunities for research in the U.S. transportation sector indicates that new materials technologies offer substantive possibilities for improving all areas related to the transportation infrastructure.
The National Aeronautics and Space Administration is charged with assuring that the United States remains a preeminent world power in space science, space operation, and space exploration, and with creating the necessary research and technology bases needed for the United States to maintain a competitive position in civilian and military aeronautics.
Materials issues pervade all aspects of NASA’s mission. Many of the challenges are unique and particularly difficult. Special emphasis is placed on weight reduction to enhance pay load capabilities. This includes not only lightweight materials, but also innovative processing and design concepts that can reduce weight while maintaining the desired level of performance. High-temperature materials are required to enhance fuel efficiency in combustion and to ensure protection during reentry. Cryogenic materials and insulation are needed for containment of cryogenic fuel and liquid oxygen. High-efficiency energy sources for space applications present critical materials problems. Environmental conditions include the high-vacuum conditions of outer space and the effects of atomic oxygen encountered in low