Growing fungi for space structural materials

Diagram depicting the mission architecture of a Mars habitat built from mycelia growth. Credits: 2018 Stanford-Brown-RISD iGEM Team / NASA

Lynn Rothschild, a scientist at NASA’s Ames Research Center in California, has just been awarded a NASA Innovative Advanced Concept (NIAC) Phase 2 grant to continue her synthetic biology studies using mycelium, the branching, thread-like structures of fungi, to “grow” space structures such as habitats, furniture and more. Rothchild previously advised a team working on mycelium production, or what she calls Myco-architecture, for habitats on the Moon and Mars. The project took place at NASA Ames as part of the iGEM Competition in the summer of 2018, and was funded by a NIAC Phase 1 award. Called Stanford-Brown-RISD or Myco for Mars as the they called themselves, the team was composed of students from Stanford University and the duel degree program of Brown University and the Rhode Island School of Design.

This new phase of the research will continue development of mycelia production, fabrication, and testing techniques. Rothschild describes the process on the NASA Myco-architecture Project site: “On Earth, a flexible plastic shell produced to the final habitat dimensions would be seeded with mycelia and dried feedstock and the outside sterilized. At destination, the shell could be configured to its final inner dimensions with struts. The mycelial and feedstock material would be moistened with Martian or terrestrial water depending on mass trade-offs, and heated, initiating fungal (and living feedstock) growth. Mycelial growth will cease when feedstock is consumed, heat withdrawn or the mycelia heat-killed. If additions or repairs to the structures are needed, water, heat and feedstock can be added to reactivate growth of the dormant fungi.”

Artist rendering of a habitat grown on Mars from mycelia. Credits: Emilia Mann / 2018 Stanford-Brown-RISD iGEM Team / NASA

This research joins other studies in synthetic biology advancing space settlement such as using fungi to seed asteroids for making soil to be used in space settlement agriculture, microbial lawns for radiation shielding, or cyanobacteria for life support systems.

A simple inflatable Mars Habitat

Called “Space Nomad” the concept, conceived by Gábor Bihari at the University of Debrecen, Hungary and Thomas Herzig, CEO of Pneumocell Co., Vienna, Austria is described in paper available on Academia.edu. The elegant design takes into account the payload capacity of spacecraft of the near future and in situ resources available on Mars to arrive at a safe and feasible solution.

Artist’s rendering of a cross section of the Space Nomad habitat. This option of the settlement is made of several longitudinal inflatable tubes. The regolith ceiling protrudes to provide the proper shielding. The mirrors reflect sunlight into the structure all day. Credits: Gábor Bihari, Thomas Herzig

The main side wall is a tri-layer membrane with two gaps to provide insulation. The outer wall gap contains a vacuum and the inner one is gas-filled. The protruding ceiling provides shielding from radiation and protection from micrometeorites that impinge at high angles to the structure. The habitat is not completely closed as the design has a system for processing the Martian CO2 atmosphere, conditioning it for use by the greenhouses while producing breathable air and replenishing losses.

Artist’s illustration of the wall and roof structure of Space Nomad. Credits: Gábor Bihari, Thomas Herzig

A modified version of the habitat could be deployed at the Moon’s polar region as a preliminary step toward validation of the design before a Mars mission. Unlike the Mars settlement, this structure would have to be airtight and changes would be required to the mirror system.

Illustration of a modified circular version of Space Nomad as a proving ground for technology at the Moon’s polar region. Credits: Gábor Bihari, Thomas Herzig

Lava Hive: ISRU Mars habitat

Stepwise illustration of the casting process to produce the Lava Hive; (1) deposition of foundation base, (2) regolith is gathered and sintered into a flow channel, (3) molten basalt from the sand/regolith is poured into the channel and allowed to solidify, (4) the next layer of regolith is spread across, and another channel sintered, (5) layer by layer the structure is constructed, (6) loose, un-sintered regolith is excavated from the structure, revealing the completed dome. Credits Aidan Cowley, et al.*

In a paper posted on Academia.edu, the 3rd prize winner for the 2015 NASA 3D Printed Mars Habitat Centennial Challenge called Lava Hive is described by a team* of European researchers. The habitat is produced by additive manufacturing via a ‘lava-casting’ construction technique and utilizing recycled spacecraft structures. Innovations include ‘re-use’ of discarded landing vehicles as part of the central habitat, 3D printed adjacent structures connected to the central habitat and use of a novel ‘LavaCast’ process to fabricate solid structures resistant to radiation and thermal cycling.

Illustration of the Lava Hive. The central habitat core is shown with the smaller 3D printed satellite structures clustered around it. Credits: René Waclavicek, LIQUIFER Systems Group, 2015

The Lava Hive Mars settlement has a number of advantages including a modular design with the ability to expand or adapt to changing mission requirements while “living off the land” with a simple ISRU process utilizing Martian soil, thereby reducing the amount of mass that would need to be launched from Earth.

* Authors of this paper are: Aidan Cowley, Barbara Imhof, Leo Teeney, René Waclavicek, Francesco Spina, Alberto Canals, Juergen Schleppi, Pablo Lopez Soriano