Aluminum based metal matrix composites are particularly attractive in aviation and aerospace applications because of their exceptional strength and stiffness-to-density ratios and superior physical properties. A vast range of composites have been fabricated with reinforcements such as glass, ceramic particulates and fibers, and more recently carbon nanotubes. Carbon nanotubes present considerable improvement in properties of the composite but suffer from problems of galvanic corrosion at the interfaces. Other nanotubes that are not galvanically detrimental to the composite are required for design of ultrastrong composites. Boron nanotubes are attractive in this respect, as they are lighter than carbon and are not very far removed from aluminum in the electrochemical series, thus avoiding corrosion issues, while retaining the excellent mechanical properties of carbon nanotubes. MMI's proposed technology that produces composites comprising boron nanotubes will have the considerable impact on future structural applications of NASA.