Space Resources – From the Moon to Near-Earth Asteroids and Back
Dennis Harries1
European Space Resource Innovation Centre (ESRIC), Luxembourg Institute of Science and Technology/Luxembourg SpaceAgency. 41, rue du Brill, 4422 Belvaux, Luxembourg (dennis.harries@esric.lu)

1Space exploration is a frontier that challenges creative and sustainable use of extraterrestrial materials. Whilst space missions
during the past decades entirely relied upon supplies brought from Earth, future missions aiming at long-term human androbotic activity outside of Earth’s atmosphere require technologies to produce propellants, life support, and construction
materials from local extraterrestrial resources. This in-situ space resource utilization (ISRU) is key for the exploration of theMoon and Mars and to make space transportation more economical and environmentally sustainable. Examples are in-orbit
fuelling and refuelling of spacecrafts, as well as the resource-efficient and circular processing of materials for building habitats
and photovoltaic energy infrastructures.
The Moon’s south polar region will a primary target for long term exploration starting with the international Artemis missions
led by NASA. This area is particularly interesting due to its permanently shadowed regions (PSRs) inside polar craters, which
are expected to hold water ice and other volatiles trapped by the very cold temperatures within. Remote sensing and the impact
experiment of NASA’s LCROSS mission places constraints on the amount and composition of volatiles, confirming thepresence of water ice at several volume percent of the regolith [1]. Hydrogen gas produced from PSR ices or imported fromEarth is the basis of oxygen generation from lunar ilmenite through redox reaction (FeTiO3 + H2 -> Fe + TiO2 + H2O) andelectrolysis of the produced water. Alternative to this is the electrolysis of lunar regolith itself in the FFC Cambridge process
employing a molten calcium chloride electrolyte. The FFC process reduced not only ferrous oxides but almost the entire oxide
components of the regolith to produce a high yield of oxygen. Both processes require volatiles (hydrogen, chlorine) that need
to be efficiently recycled due to their limited abundance on the lunar surface.
Carbon and nitrogen compounds such as CO2 and NH3 are present in PSRs, but their overall abundance is uncertain and in caseof CO2 suitable traps may be rare [2]. With typical carbon and nitrogen concentration of 10s to a few 100s of ppm in theaverage lunar regolith, mainly through solar wind implantation, both elements are geochemically highly limited but, besideshydrogen, essential for life support and most propellants. For propellants a sustainable circularisation of volatiles is obviously
not possible.
Ryugu and its potential near-Earth asteroid (NEA) siblings are now confirmed to containup to ~6.8 wt% H2O [3] chemically bound in serpentines and smectites. Up to ~4.6 wt%
of carbon are present as carbonates and organic matter that also contains considerable
amounts of nitrogen. As discussed above, hydrogen, carbon, and nitrogen are criticalresources for extended lunar presence and chemical manufacturing of propellants inspace. As carbon and nitrogen are especially limited on the lunar surface, the retrieval ofsuch resources from NEAs might become a long-term option for a sustained spaceeconomy. These asteroids are comparably easy to reach with low Δv requirements fromand into cis-lunar space [4]. Exploratory heating experiments of C-type chondritic
meteorites using high-vacuum extraction and mass-spectrometric detection of released
volatiles indicated complex release patterns of H2O, CO2, CO and nitrogen compounds(Fig. 1). Thermodynamically valuable CO appears to be a major species and likely theresult of redox reactions involving the carbonates, organic matter and magnetite.
Extraction yields, energy requirements, and catalytic chemical conversion of thispotential feedstock into further products, such as fuels and oxidizers, are some of the tobe-studied process constraints for NEA-based ISRU. Operating on small, nearlycohesionless rubble-pile asteroids is another extreme challenge for both small body Figure 1: Volatile species detected byquadrupole mass spectrometry duringexploration and any future ISRU.
References[1] Colaprete A. et al. 2010. Science 330:463–468. [2] Schorghofer N. et al. 2021.
Geophysical Research Letters 48:e2021GL095533. [3] Yokoyama T. et al. 2022. Scienceeabn7850. [4] Jedicke R. et al. 2018. Planetary and Space Science 159:28–42.

controlled high-vacuum heating of theMurchison CM2 chondrite at 10K/min. A. normalized ion currents. B.
Species after fragment patterndeconvolution.