Speaker
Description
To allow a zero-waste circular economy in space, technologies to turn heterogeneous metal-rich waste streams into new usable products in situ must be developed. While recycling space debris is one target application, such a system can also be used to process byproducts from space resources utilization. Such byproducts are for example generated by the molten salt electrolysis (MSE) process currently under development to produce oxygen from the lunar regolith. Recent work from ESA and its partners showed that MSE can remove up to 96 wt.% of the oxygen present in regolith simulant, leaving behind solid waste rich in useful metallic elements (e.g. Si, Al, Fe) [1]. The productive use of those metallic byproducts however still has to be demonstrated. A candidate technology to manufacture mechanical parts directly in space from those recovered metals is Metal3D, a system developed by Airbus & ESA to demonstrate metal based additive manufacturing in space [2].
The presented work aims to combine MSE of lunar regolith with the Metal3D technology, to demonstrate a first ever end-to-end process from lunar material to metal alloy parts. This starts with a detailed characterization of the metal-rich byproducts of the MSE process. Post-processing steps are then designed accordingly, to yield specific alloys in sufficient quality and quantity to be used for additive manufacturing. A key consideration is the variability in material composition throughout the process, linked to changes in the regolith feedstock and to the repeatability of the MSE process. Assessing the overall resilience of the proposed solution to such changes is critical in evaluating its potential to process metallic waste from both space resources processing and space debris removal.
We propose to present first characterization results of metals derived from the molten salt electrolysis of regolith simulants, with an evaluation of material variability. The heterogeneous nature of the material will be highlighted, together with the presence of intermetallic phases from the Al-Si-Ca & Al-Si-Fe systems. The alloy feedstocks that can be gained from this (e.g. Aluminium, Silumin) and potential post-processing strategies will be discussed. Finally, the overall vision for an end-to-end process will be presented, highlighting its potential for a zero-waste approach to the use of space resources, and its possible synergies with the recycling of space debris.
References:
[1] Lomax, B.A., Conti, M., Khan, N., Bennett, N.S., Ganin, A.Y., Symes, M.D., 2020. Proving the viability of an electrochemical process for the simultaneous extraction of oxygen and production of metal alloys from lunar regolith. Planetary and Space Science 180, 104748. https://doi.org/10.1016/j.pss.2019.104748
[2] Airbus Defence & Space, 2022. In space manufacturing and assembly. https://www.airbus.com/en/newsroom/news/2022-05-in-space-manufacturing-and-assembly (accessed 12/07/2023).
