Exploring Microgravity Liquid Printing Based on Resin Solidification for Outer Space Applications

Abstract

Space traveling, extra-planetary exploration and even colonization requires to replicate our capabilities of manufacturing under non-entirely known environments and conditions. With the recent, yet always present, interest on colonizing spaces like the Moon or even Mars, space-based Additive Manufacturing (AM) has been considered for enabling space inhabitants to build their own tools. However, the same manufacturing techniques that are commonly used on Earth are not entirely applicable in space, especially during the considerably long traveling stage. Thus, several works have reported the study of how AM could be used in microgravity or near-zero g conditions by using the International Space Station as a laboratory. Unfortunately, the costs for doing such experiments are prohibitive, which is why experimentation in microgravity conditions on Earth is promising. In this paper, we explore the possibility of applying light-sensitive resin under Microgravity conditions using a Drop Tower facility and we propose a microgravity liquid printing technique. Our preliminary experiments focused on studying movement and extrusion velocities, extrusion nozzle diameter, UV light power, extrusion, and solidification times. The experimental runs (one catapult launch and four drops) let us find promising, although not entirely conclusive, data and practices to be considered in future works using this methodology. As expected, there is a similarity to liquid extrusion on Earth given that the initial shape and speed of extrusion influences the liquid material. Our findings also suggest that an initial contact point would help to increase the contact force due to surface tension and that the extrusion and solidification times are less than 5 seconds, which implies faster printing processes than in earth gravity conditions because the microgravity provides us less layer mixing during extrusion. The hardware, material and Microgravity drop tests used confirm the feasibility of this technique and they become an initial step for this printing process and liquid materials.