<title>Autophagous spacecraft composite materials for orbital propulsion</title>

Abstract

We are developing structural polymer composite materials that can be converted into fuels and combusted with oxidizers for orbital propulsion of spacecraft. We have identified candidate materials and demonstrated sustained combustion with nitrogen tetroxide (NTO) as an oxidizer. To improve reaction chemistry we have evaluated several energetic additives. Detailed material compatibility tests were conducted to identify stable combinations of structural polymer and energetic additives. We have also demonstrated sustained combustion of structural polymeric materials with embedded additives and NTO. In the next phase of research, we plan to investigate hydrogen peroxide as the oxidizer. Samples of composites comprising thin metallic facesheets, structural polymer propellant matrix, and metallic mesh reinforcements (that also serve as electrical heaters/igniters for pyrolysis) were fabricated and their mechanical properties were measured. Concept of a spacecraft structural stringer, which also functions as a thruster, was developed using the composite material formulation. Both all solid and hybrid stringer-thruster designs have been developed. Prototype stringer-thrusters will be fabricated and tested in Phase II.

Towards enduring autonomous robots via embodied energy

“…The structural requirements for launching vehicles into space greatly exceed those needed for normal operation; with the components consequently sized for launch, the lifetime and efficiency of these vehicles would increase by breaking down and harvesting energy from their excess materials. This same strategy could be implemented in robots, and is supported by research involving autophagous metal-air batteries 62 , structural beams pressurized with gaseous fuels 61 , and thermoplastic matrix composites that can be converted to fuel and burned with liquid oxidizers 63 .…”