The major space programs such as Artemis all attempt to establish a permanently manned
base on the surface of the Moon. To achieve the old dream of a space colony, humanity must
ensure astronauts’ long-term autonomy in extreme environments like the Moon’s surface. In-Situ
Ressources Utilization (ISRU) is an acronym created to cover any technology that can help to
replace material that has to be brought from Earth otherwise. The lunar soil, so-called regolith,
has been investigated as a source material for manufacturing objects in a wide range of scales,
with a huge focus on additive manufacturing which allows great flexibility.

Lunar regolith is a complex mineral material, mostly in powder form, composed of a wide variety
of oxides and of grain shapes and sizes, in both crystalline and amorphous phases, due to
its formation mechanism and space weathering. To demonstrate the viability of ISRU technologies,
the use of ground natural Earth rocks as lunar regolith substitutes called either simulants or
analogs has become prevalent. The idea of Powder Bed Fusion techniques applied to regolith
is recent but not new: its feasibility under variable physical parameters (pressure, gravity) has
already been experimented by a few laboratories across the world. However, there is still a
lack of understanding regarding the links between the process, the initial composition, and the
obtained microstructures and properties.
Focused on selective laser melting, this current work aims at establishing relationships between
the different parameters involved in the process and the obtained mechanical properties
and microstructures, using two complementary approaches:
On the one hand, a fundamental study has been conducted on a series of analogs, prepared
from an unweathered basaltic lava flow in the Pic d’Ysson (Massif Central, France), then doped
with different amounts of amorphous or crystalline oxides to encompass all the diversity of the lunar
regolith. The behavior of those granular materials during thermal cycles through their phases
transformations (XRD, DSC, and TMA curves), thermal conductivity, and absorptivity is a first
indicator of what happens when the regolith is exposed to a laser beam.
On the other hand, additive manufacturing trials complemented by corresponding micro indentation
and compression tests have been done, offering the opportunity to evaluate the impact
of four SLM machine-related parameters: laser power, scanning speed, hatching distance, and
laser spot size. An optimal range of volumic energy supplied to the mineral powder could thus
be identified to reduce melt defects and porosities of the resulting ceramic objects. With further
developments, the coupling of the fundamental and applied approaches should lead to a coherent
strategy for processing optimized ceramic materials directly from lunar soils.