The future of Mars habitats using concrete 3D printing is promising, with significant potential for cost savings, customizability, and safety compared to traditional construction methods.
The notion of colonizing Mars has been a dream of scientists, engineers, and entrepreneurs for several decades. However, in recent years, there have been significant strides in developing the technology needed to make a human presence on the red planet. Concrete 3D printing technology has received much attention in the digital world due to its potential benefits include high level of automation, minimal wastage, and robustness. Moreover, this technique can be used to construct habitats on Mars. The Red Planet’s harsh and inhospitable environment requires structures that can withstand extreme temperature fluctuations, high levels of radiation, and atmospheric pressure that is much lower than Earth’s. This 3D printing technology also allows building structures on the Red Planet without transporting large amounts of building materials from Earth. Instead, the abundant materials on Mars such as Martian soil, rock, and ice could be used to produce the concrete mixture on-site.
The use of conventional methods in the construction of habitats on Mars is not feasible due to the harsh environment. Mars is a planet with high level of radiation making it difficult for humans to survive without the protection of human habitat. The cost and logistic challenges of transporting traditional building materials and equipment from Earth to Mars is uneconomical. Concrete 3D printing, however, offers a solution to these challenges using locally available materials and autonomous robots for the construction process. Mars has abundant deposits of regolith, which is a mixture of sand, gravel, and dust that covers the planet’s surface. Regolith can be processed into a form of concrete called “Marscrete,” which can be used to build structures .
Another advantage of concrete 3D printing is the potential for increased speed and efficiency in construction. However, the conventional construction methods require a significant amount of time and, human labor, which is not feasible on Mars due to the inhospitable environment and limited resources. The use of concrete 3D printing could significantly reduce the amount of materials that need to be transported from Earth to Mars, enables the creation of large and complex structures without relying on expensive and resource-intensive launches. Overall, the use of concrete 3D printing has the potential to revolutionize human exploration and settlement on Mars by enabling the creation of functional, sustainable, and cost-effective habitats.
In addition to the benefits of using local materials and autonomous construction, concrete 3D printing also offers a high degree of design flexibility. The layer-by-layer deposition of concrete allows for the creation of complex and organic structures that would be difficult or infeasible to build using conventional construction methods. This opens new possibilities for designing habitats that are optimized for the ambient conditions of Mars.
Challenges of concrete 3D printing for Mars habitat
Despite the potential benefits of concrete 3D printing for Mars habitat construction, there are still many challenges that need special emphasis to make this technology feasible. One of the biggest challenges is the development of a 3D printing system that can operate in the extreme conditions of Mars. In addition, the system must be able to operate autonomously with minimal human intervention, as it may not be feasible to send human operators to Mars to oversee the construction process.
Mars has a gravity of 3.721 m/s2 and an average atmospheric pressure of 655 Pa, with a thin atmosphere. However, the planet is exposed to harmful radiation due to the low atmospheric density. The temperature on Mars varies greatly depending on location, season, and time of day, with a range of -153° to 20° Celsius. One Martian year is equal to 687 days on Earth. Mars has a different daily and seasonal cycle than Earth due to its longer rotation and orbital period. These extreme planetary conditions pose a challenge for engineers to develop materials that can withstand the harsh environment, including resistance to erosion, corrosion, and radiation, while having a low working temperature range and being non-ferromagnetic. Materials used for space habitats must act as radiation shields to protect human life.
The study conducted at Northwestern University  focuses on the formulation of 3D printable Marscrete. Marscrete is composed of Martian soil of seventy-five percentage and twenty-five percent of molten sulfur by heating in the range of 120° to 140° C in the form of viscous slurry, and it shows better mechanical properties than conventional sulfur concrete. The addition of mission-recycled polyethylene fibers ensures the buildability of 3D-printing Marscrete. It also highlights the rheological behavior of fresh printable Marscrete and its structural performance.
Molten sulfur mixed with grains can be used for space construction due to its accessibility and recyclability. It does not require water and hardens rapidly. However, high temperatures can cause to fail, and synthesizing sulfur is a challenge. Sulfur may be present on the Martian surface, but melting under vacuum conditions remains a challenge. Sulfur concrete can withstand extreme conditions in space, however the production process must be designed well. Researchers have been exploring the use of different binders and additives, such as sulfur and iron oxides to improve the durability and strength of Martian concrete. Iranfar et al.  have explored the potential of geopolymer as the best binder for construction on Mars with consideration of fourteen technical criteria with the utilization of the Multi-criteria decision-making system.
It is also challenge to ensure that the 3D printers should have the potential to work efficiently in low-gravity and harsh environment of Mars. Developing a robust 3D printers with the ability to withstand harsh conditions enables the creation of large, complex structures that provide ample living and working space for astronauts, and offer protection from the harsh Martian environment.
There are, of course, significant technical challenges to overcome in using concrete 3D printing for Mars habitats. Developing robust 3D printable material that can withstand harsh Martian environments with structural efficacy is a crucial part of Mars habitation. Finally, ethical and legal considerations need to be considered when designing and constructing habitats on Mars. The habitats must be designed to minimize the environmental impact on the planet, and any waste generated during the construction process must be properly managed. In addition, the construction of habitats on Mars must be done as per international space law and other legal frameworks to ensure the responsible and sustainable use of space resources.
Future of concrete 3D printing for Mars habitat
Despite these challenges, there has been significant progress in developing concrete 3D printing technology for Mars habitats in recent years. NASA. in 2018, awarded a $14 million contract to AI Space Factory, a New York-based architecture and technology firm, to develop a 3D-printed habitat design for Mars. The resulting design, called Marsha, uses a cylindrical shape and a double-layered shell to protect against radiation and provide insulation and is intended to be printed using Martian soil.
In addition to NASA, several private companies are also working on developing concrete 3D printing technology for Mars habitats. For instance, ICON, a construction technology company based in Austin Texas has developed a 3D printer called Vulcan, that is capable of printing a 2,000 square foot house in 24 hours using locally sourced materials. The company has partnered with NASA to explore the use of Vulcan for building structures on Mars.
Overall, the future of Mars habitats using concrete 3D printing is promising, with significant potential for cost savings, customizability, and safety compared to traditional construction methods. While there are still some technical challenges to overcome, ongoing research and development in this area are likely to lead to increasingly sophisticated and effective 3D printing technologies for use on Mars and beyond. As the researchers continue to explore the potential of space exploration and colonization, concrete 3D printing is likely to play an increasingly important role in shaping the future of human habitation in the cosmos.
 Matthew Troemner, Elham Ramyar, Raul Marrero, Kavya Mendu, Gianluca Cusatis, Marscrete: A Martian Concrete for Additive Construction Applications Utilizing in Situ Resources, in: 17th Biennial International Conference on Engineering, 2021.
 S. Iranfar, M.M. Karbala, M.H. Shahsavari, V. Vandeginste, Prioritization of habitat construction materials on Mars based on multi-criteria decision-making, Journal of Building Engineering. 66 (2023). https://doi.org/10.1016/j.jobe.2023.105864.