Additive Manufacturing of Polyether Ether Ketone (PEEK) for Space Applications: A Nanosat Polymeric Structure.

Recent improvements in additive layer manufacturing (ALM) have provided new designs of geometrically complex structures with lighter materials and low processing costs. The use of additive manufacturing in spacecraft production is opening up many new possibilities in both design and fabrication, allowing for the reduction of the weight of the structure subsystems. In this aim, polymeric ALM structures can become a choice, in terms of lightweight and demisability, as far as good thermomechanical properties. Moreover, provided that fused-deposition modeling (FDM) is used, nanosats and other structures could be easily produced in space. However, the choice of the material is a crucial step of the process, as the final performance of the printed parts is strongly dependent on three pillars: design, material, and printing process. As a high-performance technopolymer, polyether ether ketone (PEEK) has been adopted to fabricate parts via ALM; however, the space compatibility of 3D-printed parts remains not demonstrated. This work aimed to realize a nanosat polymeric structure via FDM, including all the phases of the development process: thermomechanical design, raw material selection, printing process tuning, and manufacturing of a proof of concept of a technological model. The design phase includes the application of topology optimization to maximize mass saving and take full advantage of the ALM capability. 3D-printed parts were characterized via thermomechanical tests, outgassing tests of 3D-printed parts are reported confirming the outstanding performance of polyether ether ketone and its potential as a material for structural space application.

Can 3D bioprinting be a key for exploratory missions and human settlements on the Moon and Mars?

Fifty years after the first human landed on the Moon mankind has started to plan next steps for manned space exploration missions. The international space agencies have begun to investigate the requirements for both a human settlement on the Moon and manned missions to Mars. For such activities significantly improved medical treatment facilities on-board the spacecrafts or within the extraterrestrial settlements need to be provided as no fast return opportunities to Earth would exist anymore in case of severe trauma or illness. Bioprinting is believed to play a significant role as it could offer the possibilities to produce patient-specific tissue constructs in a semi-automated manner. Therefore, both the space agencies and the bioprinting community have started to study possible applications of bioprinting technologies in space. Besides utilisation of bioprinted tissue constructs for the treatment of injured astronauts bioprinting will become relevant for the fabrication of three-dimensional tissue models for basic research, e.g. concerning effects of microgravity and cosmic radiation on cells and tissues. This perspective article describes the current state of the art including medical scenarios for new far-distant space exploration missions, first approaches towards establishment of bioprinters in space and which limitations have to be resolved to use bioprinting under the specific conditions of space flight like altered gravity conditions.

Regenerative medicine and 3D bioprinting for human space exploration and planet colonisation.

3D printing also known as additive manufacturing (AM) is seen as one of the key enabling technologies for a large number of high-end industrial sectors including the automotive, aerospace and medical industry. Recent advances and breakthroughs in the last years have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine, addressing the need for tissues and organs suitable for transplantation. Bioprinting implies additional complexities related to the sensitivities of living cells such as printing parameters and conditions, material selection, cell types etc. Despite these challenges, beating artificial heart cells, cartilage implants, skin repairs, functional kidney tissues have been printed successfully on Earth. The present paper addresses the possibility of performing regenerative medicine in space, which may guarantee sustainable life support on long term/long distance planetary exploration missions, opening to stable planet colonisation.

Challenges in Additive Manufacturing of Space Parts: Powder Feedstock Cross-Contamination and Its Impact on End Products.

This work studies the tensile properties of Ti-6Al-4V samples produced by laser powder bed based Additive Manufacturing (AM), for different build orientations. The results showed high scattering of the yield and tensile strength and low fracture elongation. The subsequent fractographic investigation revealed the presence of tungsten particles on the fracture surface. Hence, its detection and impact on tensile properties of AM Ti-6Al-4V were investigated. X-ray Computed Tomography (X-ray CT) scanning indicated that these inclusions were evenly distributed throughout the samples, however the inclusions area was shown to be larger in the load-bearing plane for the vertical specimens. A microstructural study proved that the mostly spherical tungsten particles were embedded in the fully martensitic Ti-6Al-4V AM material. The particle size distribution, the flowability and the morphology of the powder feedstock were investigated and appeared to be in line with observations from other studies. X-ray CT scanning of the powder however made the high density particles visible, where various techniques, commonly used in the certification of powder feedstock, failed to detect the contaminant. As the detection of cross contamination in the powder feedstock proves to be challenging, the use of only one type of powder per AM equipment is recommended for critical applications such as Space parts.