Universe Today
All long-term plans for human space exploration and research depend upon habitats that allow for long-duration stays. To date, most concepts involve surface habitats that leverage in-situ resource utilization(ISRU) for building materials and construction techniques. However, additional planning has been directed towards habitats that take advantage of underground recesses, such as stable lava tubes. These features have been noted on both the Moon and Mars and offer several advantages over surface habitats.
For example, subsurface recesses maintain comfortable living room temperatures and are shielded from cosmic radiation, meteorites, and surface dust. Through the NASA Advanced Innovative Concepts(NIAC) program, several interesting technologies are being researched to help build and maintain these habitats. In a recent study, a team of researchers explored candidate lava tubes and dike tip voids and how developments funded by the NIAC program could be utilized to build bases in them.
The study was conducted by Christopher Maurer, the Principal Architect at redhouse studio architecture;Prof. James Head, the Louis and Elizabeth Scherck Distinguished Professor Emeritus Professor of Geological Sciences at Brown University; and Lynn J. Rothschild Maurer, a Senior Research Scientist and the Bio and Bio-Inspired Technologies, Research and Technology Lead at NASA's Space Technology Mission Directorate(STMD). Their paper was presented at the 2025 Lunar and Planetary Science Conference(2025 LPSC) from March 10^th^to 14^th^in Woodlands, Texas.
Possible Locations:
Planetary research has revealed that multiple rocky bodies in the Solar System—including Mercury, the Moon, and Mars—have stable lava tubes and underground recesses. Like Earth, these are attributed to volcanic activity, which all these bodies experienced early in their history. These volcanoes produced lava flows whose surfaces cooled and solidified, leaving behind subsurface tubes that are usually accessible through collapsed sections of holes in the roof (known as "skylights.")
Whereas lava tubes on Earth typically measure 10 to 100 meters (33 to 330 ft) in diameter, these features are much larger on the Moon and Mars. Orbiter missions have identified tubes on Mars that are 100 times wider, while lunar tubes have been observed that are 1000 times wider - large enough to fit entire cities within! Recent research has also revealed how eruptions on the Moon and Mars often consist of "dikes," where magma rises into an existing fracture or creates a new crack by forcing its way through the existing rock.
These eruptions often stall due to gas separation as they approach the surface, creating "linear dike-tip voids" extending several kilometers in length and about 250 m (820 ft) in height. These two candidates, near-surface lava tubes and linear dike-tip voids, provide a potentially abundant source of habitats on the Moon and Mars that protect against the elements but do not require significant construction on the surface.
Methods:
To summarize, ISRU techniques require significant building materials, energy resources, and water, all of which must be harvested locally. Various methods have been proposed for leveraging 3D-printing technology and using lunar or Martian regolith as the feedstock. These include mixing the regolith with a bonding agent to create "lunacrete" and sintering the regolith with microwaves to create a molten ceramic that can be printed on the surface.
However, other concepts have been explored through the NIAC program, including synthetic biology, structures grown using fungal mycelium (Myco-architecture), and flexible, foldable, and inflatable forms. Whereas ISRU techniques already reduce the total mass that needs to be launched from Earth, the ability to grow structures on-site via Myco-architecture-enabled techniques dramatically reduces it further. As Maurer told Universe Today via email:
"The concept in this abstract is based on our work together in the NIAC program. We're currently in phase III of the program to develop buildings and building assemblies that can be grown off-planet. By growing materials at the destination, we can save trillions of dollars in the mass transport of materials and do not need to rely on in situ resources that are nowhere near as multifunctional as our biomaterials. The materials we're developing utilize fast-growing fungi to create thermal and radiation-insulative materials that are outperforming current industry leaders. When used in conjunction with tightly packed inflatables it solves all of the architectural needs of structure, thermal insulation, pressure barrier, and radiation shielding. "With the Lava tube study, we envision using an axially growing tube to form a solid, structural, insulative, radiation attenuating barrier to shore and seal the lava tubes for safe building. It's very similar to a system plumbers use to fix broken pipes that cannot be accessed called cured in place pipe - CIPP. A liner is released and inflated, then UV light is used to cure embedded resins that harden in place. Here, we replace the UV-cured resins with microorganisms that grow within bioreactors in the liner."
Challenges:
Despite the advantages of lava tubes and voids, building habitats underground presents numerous challenges. For instance, there is the danger of wall and ceiling collapse, the necessity of airlock systems at the skylights, and the potential of regolith from collapsed sections and openings elsewhere along the tube or void. To address these issues, the authors present advances in inflatable structures and Mycoarchitecture, which could work in tandem to create and reinforce structures.
Regarding the former, they cite advances in "soft robotics" (aka. apical expanding robots) inspired by fungal hyphae growth, which has applications in search and rescue, construction, and medicine. Examples include inflatable tube robots that can increase their size by 250 times at a rate of 10 m/s (33 ft/s). There has also been significant research into UV-cured plumbing liners - cast-in-place pipes (CIPPs) - used to repair damaged pipes and create new ones.
Per their proposal, they envision an outer inflatable shell coated with UV-curing resin to form a structural lining in long lava tubes, followed by an apical extended tube that forms the interior environment. The space between the two is then filled with water and hydrogel to form a matrix for the growth of a bioengineered radiation-resistant fungus. Once the hydrogel and fungi are fully integrated, it can be frozen to produce an aerogel.
These proposals present opportunities for future robotic and crewed missions to explore shallow lava tubes and dike tip voids on the Moon and Mars. They also highlight how the development of new technologies is creating opportunities for NASA's "Moon to Mars" mission architecture.
Further Reading:USRA