3D printing of composites for space applications

Abstract

Additive manufacturing (AM) has recently been adopting a wide variety of materials ranging from plastics, metals as well as their composites and alloys. Food, fabric, concrete and cement are amongst the new printable materials that have been considered commercially. The application areas of AM have also ever been expanding toward the field of space engineering beyond terrestrial applications. Researchers and entrepreneurs are actively investigating the potential of three-dimensional (3D)-printed composites to achieve the short-term goal of affordable access to space and the long-term goal of mankind's prolonged existence beyond Earth, namely, space habitats on the Moon, Mars, etc. The short-term goal involves AM of composites and metals, whilst the long-term goal necessitates AM of new printable materials encompassing nearly all facets of our everyday lives. Materials types other than composites are left as future work in accordance with the advent of novel AM methods and space exploration campaigns [1-3]. The focus of this chapter is to introduce (1) applications where spacecraft components made of 3D-printed composites can be used and (2) how these manufactured components can be assembled into a space system or structure.The process of 3D-printing parts for space systems may occur on the ground (Earth) beforehand or in situ on orbits. There are several examples in which rocket engines or satellite components were 3D printed and then assembled into a ready-to-launch system on the ground. SpaceX first used a 3D-printed component in 2014, which was a liquid oxygen valve in one of the nine engines inside the Falcon nine rocket - nowadays, an entire engine of a small rocket can be 3D manufactured using large-scale metal printers with robotic arms, which reduce the number of assembled engine parts by an order of magnitude [4, 5]. These 3D metal printers are heavy and power-consuming because of their laser melting process. Composite 3D printers, on the other hand, are free from these constraints because composites have much lower melting points than metals. Composite 3D printers have been installed in the International Space Station (ISS) for astronauts' use. Different versions and brands of commercial 3D printers have proved their functionality under microgravity. They are not being used outside the ISS under harsh space conditions such as vacuum, radiation, micrometeorites, etc. The first automated on-orbit AM will be demonstrated in the near future to produce structural components with large dimensions and aspect ratios. In light of this background and context, the latest development of AM technologies for composite manufacturing and assembling will be discussed within mechanical, electrical, electrochemical and medical applications in space.