Evolution of 3D printing processes and applications will have significant importance to near-term and long-term planetary space program initiatives. Long-term Martian missions will require large amount of supplies to be transported to Mars. In-situ Resource Utilization and 3D printing will reduce the interplanetary material transportation needs and thereby will contribute to more efficient Mars colonization.
In recent days, houses have been already 3D printed on Earth. Infrastructure and time required for printing makes this method very unique. The composition of Martian soil enables it to be used as a 3D printing material. Martian atmospheric composition and presence of water allows production of 3D printing binder material to be produced on the surface. The elements of Matian soil that are essential for 3D printing are Hydrogen, Oxygen, Silicon, Iron and Carbon. The binder material to be used is Polyethylene. Polyethylene is also a good radiation shielding element. Availability of Carbon Dioxide in the atmosphere and water in the soil will be important for production of Polyethylene.
It begins with deployment of central module containing all the equipment including small 3D printer.A small 3D printer will print the structural elements of large scale 3D printer. Large scale 3D printing will take place around the central module.
All essential robotics and power sources will be delivered to Mars prior to the initial settlement. Power source will be Kilowatt. Once 3D printing of habitats is finished, they will bemade Human-rated to ensure the habitability of 3D printed domes. Due to change of the physical state of material for 3D printer, there is a possibility of outgassing from a solid printed structure.
Polychlorotrifluoroethylene (PCTFE) material which has a very low permeability to CO2, O2 and N2.The spray of PCTFE will be used inside 3D printed habitat structures to minimize possible outgassing.
Multiple 3D printed domes will serve different functionalities: habitation, science and medical labs and green house. These are the essential functions that will be needed during initial settlement on Mars.
Responses
Founder of Space Architecture as a Discipline
Pratik, you raise some important points about the potential role of 3D printing to construct habitats on Mars.
However, before I address those points, let me give my standard disclaimer that Mars does not have soil,
considered as the product of a biological process of decomposition. What Mars has on its surface is REGOLITH.
You are correct that the essential elements
for your Martian concrete exist in the Mars regolith, but where are you going to get the polyethylene? On Earth, manufacturers produce polyethylene from petroleum-derived hydrocarbons, Poly(ethene) is made by several methods by addition polymerization of ethene, which is principally produced by the cracking of ethane and propane, naphtha and gas oil.
Also, a new plant in Brazil is producing polyethylene from ethene, that is made from sugar cane via bioethanol.
See: http://www.essentialchemicalindustry.org/polymers/polyethene.html
Also, please note that the form of polyethylene with the favorable radiation-shielding properties is high density polyethylene (HDPE), which requires its own particular processing to make. If you are talking about HDPE as the binder in a Mars regolith concrete mix, melting point and chemical reactions emerge as critical aspects. For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 180 °C (248 to 356 °F).
https://en.wikipedia.org/wiki/Polyethylene
But would not be enough to just melt HDPE, mix it with sand and aggregate, and expect it to bind like concrete when it cooled. Instead, you would just get a kind of polyethylene Swiss cheese with rocks in the rubbery holes. Instead, what you would need to do probably is use a thermoplastic variant, such as polyethylene terephthalate (PET), a form of polyester. PET thermosets at 500° C and probably could bind chemically to a regolith aggregate, or at least form tightly around it.
Another alternative to consider on Mars is using sulphur concrete. There are large sulphur deposits in certain regions of Mars that should be possible to extract and refine. Sulphur concrete develops approximately seven times the strength in compression of conventional hydrated Portland cement concrete. Another potentially positive feature of sulphur concrete is that it can be made with larger and coarser aggregate than Portland cement concrete. http://www.dtic.mil/dtic/tr/fulltext/u2/a101464.pdf
The one drawback of sulphur concrete is that it forms its bond when the sulphur melts after being heated above its melting point of 140° C. However, there are plenty of metals that can easily withstant that temperatiure to serve as the applicator head for the 3D printer using HOT sulphur concrete feedstock.
To make credible design and engineering progress in this exciting area of research, we would need to conduct extensive testing with the several methods of casting or 3D printing Martian concrete, and probably some additional methods as well.
