offbeat
A low-energy 3D-printing method could turn engineered yeast, gelatin, and Martian soil into durable structures.
If humans eventually reach Mars, they will need suitable shelters. One possible approach is to use yeast, gelatin, and Martian soil to 3D-print structures, according to researchers in Hong Kong.
A new paper from The Hong Kong University of Science and Technology and The Hong Kong Polytechnic University describes a method for constructing on Mars without the energy-intensive heating normally required to process regolith into building materials. Instead, the team combined bioengineered yeast, artificial gelatin hydrosol, and simulated Martian soil.
“My inspiration came from freeze-dried fruits that become harder,” said senior author Jishen Qiu, an associate professor at Hong Kong University of Science and Technology.
The proposed process begins with yeast engineered to produce adhesive proteins that bind materials together. The yeast is mixed with gelatin hydrosol to provide a growth medium, followed by Martian soil. The resulting mixture can then be extruded through a 3D-printing nozzle.
In the dry, freezing Martian atmosphere, the printed material would likely freeze-dry as its ice content sublimated. The researchers expect this to leave behind a lightweight, porous material with considerable strength.
“The hardened material achieved mean compressive and flexural strengths of approximately 12 and 6 MPa, respectively,” the team reported. Those measurements are comparable to low-grade concrete on Earth. The process also requires roughly one to two orders of magnitude less energy than methods that heat-process Martian or lunar regolith.
The material may also be breakable down and reused if at least one yeast cell survives the process. Whether yeast could remain viable under Martian conditions remains uncertain, although future builders could potentially maintain a supply for subsequent projects.
The researchers tested the concept by printing small, beehive-shaped structures under simulated Martian conditions. Each specimen stood just 45 millimeters, or less than two inches, tall.
Qiu said he sees no physical law or fundamental mechanism preventing the process from working at a larger scale.
Scaling the technology remains one challenge. Another is determining whether the yeast-gelatin foam can maintain the pressure needed to protect occupants from the Martian environment, an area that the researchers said was outside the scope of this study.
The paper notes that a practical lunar or Martian habitat would also need to provide gas tightness, structural support, thermal regulation, radiation shielding, dust protection, repairability, and resource recycling. Such a habitat may therefore require hybrid construction combining the printed foam with more conventional materials and systems.
Avoiding high-temperature processing could significantly reduce the energy and heavy equipment needed for construction, although further testing is required before the material can be considered for human habitats.