Title: ''Solar 3D printing of lunar regolith "
Abstract: In-Situ Resource Utilization (ISRU) has become in the last decades one of the most prominent approaches for the building of a settlement on the Moon. The use of local resources to reduce up-mass, cost and risk of mission is now an essential consideration in future exploration scenarios. Within this trend, lunar regolith, the loose layer of crushed rock covering the Moon surface, has a key role to play. Its high metallic oxides content could offer a sustainable way of producing oxygen and it could also be used as a construction material via, for instance, a sintering process. By means of solar concentration, microwaves or radial heating elements, this process would create solid building elements that could be used for roads, launch pads or habitats. Additive manufacturing (AM) technology, commonly called 3D-printing, is widely used on Earth. Building parts layer by layer allows the realization of complex shapes, does not create wasted material, and requires low post-processing work. The shift from casting to AM in aerospace and automotive industries shows the leading place given today to such technology. AM in microgravity has already been used in space since 2014 with a first polymer 3D printer on-board the International Space Station (ISS). Combining AM with ISRU offers a way of building-up a permanent lunar outpost with a limited amount of upload from Earth. Proof of concepts using lunar regolith as main building material were given with the contour crafting and D-shape approaches. Both technologies create a mixture similar to concrete with the lunar soil and terrestrial consumable materials. Making any large-scale construction is therefore dependent on Earth shipments which is not viable for long term missions. In this work we demonstrate how, only using concentrated sunlight, we can 3D print a solid material from lunar regolith.
In the DLR solar oven, a custom solar 3D printer was constructed capable of sintering building elements using only lunar regolith simulants and concentrated sunlight. The realisation of various shapes has proven the concept, opening the path to further improvements and more challenging constructions designs.
1. Solar 3D printing of lunar regolith
Alexandre Meurisse
April 12th 2018
2. The project aims at developing a 3D-printing process for fusing/melting/sintering model lunar soil
material with the use of concentrated solar energy. The intended first result is a brick-sized model
building block of a lunar base outer shell made from model material. The project shall study various
parameters of the production process as well as of the model lunar soil in order to better understand
and optimise the overall process also in view of application on the Moon.
ESA-GSTP: 3D printing of a model building block for a lunar base outer shell (2015-2017)
Background & Context
The establishment of a permanent base on the lunar surface will require the construction of roads and
habitats shielding from meteoroids and space radiation. In-Situ Resource Utilisation (ISRU) would be a
solution to reduce up-mass, cost, and risk of such lunar mission.
Solar sintering of lunar regolith
3. ESA-GSTP: 3D printing of a model building block for a lunar base outer shell
Solar 3D printing of lunar regolith
DLR-Cologne Solar Oven
8. Xenon High-Flux Solar Simulator
Steady light conditions
Higher sintering quality
Closer to the lunar environment
Power density
1.2 MW/m²
ESA-GSTP: 3D printing of a model building block for a lunar base outer shell
9. ESA-GSTP: 3D printing of a model building block for a lunar base outer shell
Solar 3D printing of lunar regolith
10. Solar 3D printing of lunar regolith
ESA-GSTP: 3D printing of a model building block for a lunar base outer shell
14. Solar 3D printing of lunar regolith
ESA-GSTP: 3D printing of a model building block for a lunar base outer shell
ESA-RAL AML: Particle size analyser
17. Traditional sintering
Commun sintering parameters
Pre-compaction 255MPa
Sintering time 3h
Heating rate 400°C/h
JSC-1A sintered in air JSC-1A sintered in vacuum
25mm
20mm
Simulant JSC-1A JSC-2A DNA FJS-1 NULHT
Environement Air Vac. Air Vac. Air Vac. Air Vac. Air Vac.
T(°C) 1125 1100 1130 1090 1100 1070 1125 1090 1200 1200
20. Radiation shielding
HZE, High energy ions
neutrons
- “The purpose of shielding is to reduce exposure […] as low as reasonably achievable.”
Ref: Turner, Ronald. "Solar particle events from a risk management perspective." IEEE transactions on plasma science 28.6 (2000): 2103-2113.
Ref: C. Zeitlin, S. B. Guetersloh, L. H. Heilbronn, and J. Miller. Measurements of materials shielding properties with 1GeV/nuc 56Fe. Nuclear
Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 252(2):308–318, 2006.
21. ISIS Neutron and Muon Source
RAL Space
Harwell Science & Innovation Campus
23. Radiation shielding
We count the neutrons with a silicon detector before and after the samples
Samples
Powder samples were
placed in an aluminium
tube and then wrapped
in aluminium foil.
Neutron
flux
Si Detector
Si Detector
Sample
holder
24. Radiation shielding
Experimental set-up
We count the neutrons with a silicon
detector before and after the samples
A second device « ESA-SRAM »
cross-checks the neutron counts
Counter 1, 2 and 3 is the same
counter with different
thresholds
25. Radiation shielding
Interaction Depth: X= ρ . 𝑑𝑟
Results
We measured JSC-2A at powder state,
traditionally sintered in vacuum and solar
sintered. Also aluminium for comparison
purposes.
The results are compared with Monte-Carlo
simulations
The depth is in g.cm-2 as the material density
is integrated by its thickness in order to plot
all the results together.
In principle, all JSC-2A samples should be
aligned.
ρ: 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙′ 𝑠 𝑑𝑒𝑛𝑠𝑖𝑡𝑦
26. TRL 5
TRL 4
TRL 3
TRL 2
TRL 1
TRL 6
p.
26Funded by EU-Horizon 2020
Planning the next step
• First solar 3D
printing of lunar
regolith
• Mobile 3D printing head
• Solar sintering in
vacuum
• Traditional sintering
of lunar regolith
* Building bigger
elements in a relevant
environment (vacuum,
reduced gravity)
* Mission scenario &
Readiness
* Improved mechanical
properties
* Material scientific
understanding of material
27. p.
27Funded by EU-Horizon 2020
Solar sintering
Mobile 3D printer
• demonstrates printing operations
in an operational setting closer in
scale to one that would be used
on the moon surface
• comprised of a lightweight lens
oriented in a 3-dimensional space
• lens moves, as opposed to the
sintering bed
• allows the construction of larger
building blocks
reuses:
feeder (FEMA)
software components (NCGU)
28. p.
28Funded by EU-Horizon 2020
Solar sintering
Mobile 3D printer
Campaign II - Example of printed layer with
enhanced resolution of mobile printing head
29. p.
29Funded by EU-Horizon 2020
Solar sintering
Vacuum 3D printer
• similar to the ambient 3D printing
system
• compatible with a vacuum
chamber
• modifications include:
• reduction in capacity of the
hopper (FEMA)
• disposition and geometry of
the auger conveyors (FEMA)
30. p.
30Funded by EU-Horizon 2020
Building Elements
Interlocking building elements
• Extensive geometric studies
were undergone
• geometries are adapted in an
iterative process after each
sintering campaign in
coordination with the material
tests
Tetrahedron
• self-centers during construction
- eliminating the need for
external scaffolding
• has sharp edges and allows the
construction of a completely
sealed habitat envelope
Optimization of the tetrahedron interlocking
building element; final geometry pictured in version
13.
31. p.
31Funded by EU-Horizon 2020
Building Elements
Lunar habitat envelope
constructed through tetrahedron
elements
The interior can be outfitted with
inflatable pressure-bearing
volumes to create inhabitable
zones
