In 2015, NASA Administrator Charles Bolden named 2030 as a target date for landing on Mars.
If humans end up on Mars in the next ten years, astronauts will need to use as much of the planet’s resources as possible, and potentially build habitats to stay there.
Researcher Javier Gomez Fernandez and his team have an answer for how to build homes on Mars, and it involves a mysterious, high-strength material found in nature.
Listen to this episode of Here's an Idea to learn about the key ingredient that Fernandez wants Mars explorers to take along on their journey: Chitin. The podcast also reveals why we may just need bring 100 cricket eggs on the nine-month trip, too.
Chitin, found in the exoskeleton of insects and hard structures in invertebrates, can combine with components like calcium carbonate to make super-hard surfaces like a clam shell.
And the natural substance is everywhere, almost as abundant as cellulose. Over 1 billion tons of chitin are synthesized each year by organisms.
When combined with soil from the surface of the Red Planet, the chitin forms a kind of muddy concrete that can be used to make everything from a wrench to a Mars habitat. There is a significant increase in the material's flexural strength as regolith is added and approaches a 1:75 ratio.
Such a sustainable, eco-friendly approach to manufacturing has its benefits on Earth as well.
We spoke with Javier Gomez Fernandez from the Singapore University of Technology and Design about how Mars explorers can make the most out of chitin.
- (2:47) Can We Really Envision a Mars Habitat Made Entirely from Chitin?
We have like this amazing molecule that nature is using. It makes the structures of the wings of insects, the joints so you can make elastic or stiff components. Why can't we use this component in the same way?
- (3:57) What Does the Finished Material Look Like?
It feels like concrete, but it's much lighter than concrete.
- (6:09) Are We Really Bringing Bugs to Mars?
- (7:05) What Can You Make?
We demonstrated that indeed you can reproduce the structural properties of chitin. In the last 10 years, we moved from this kind of conceptual idea of merging natural components and natural designs to technologies that are able to produce, like, turbine blades.
- (14:25) What Does NASA Think of the Idea?
Additional Resources: A Q&A with Fellow Researcher Shiwei Ng
We also spoke with Javier's colleague Shiwei Ng via email.
Here's an Idea: To create the concrete, what is the ratio of chitin to Mars regolith?
Shiwei Ng: The ratio we used is 1:75. Meaning that for every gram of dry chitin component, there is 75g of regolith.
Here's an Idea: Also, to make something like a wrench: What machinery is required? Do you feed the concrete-like material into a 3D printer?
Shiwei Ng: To make a wrench, it is just casting it manually into a mold. The casting process needs no machinery at all. But to make the mold, you might have to 3D print one first and then we will be able to reuse the same one over again.
You can choose to print a wrench with the same material but we have not demonstrated that aspect. Here, we chose to 3D print a model of a Martian habitat instead. Rather than a conventional desktop 3D printer that uses plastic filament, it might help to think about the set-up we used as one that is nearer to a concrete printer that extrudes cementitious material.
Here's an Idea: How is the chitin obtained, especially for the first trip to Mars? Is the idea that we bring a load of insects on the trip to Mars?
Shiwei Ng: For the first trip, we could bring insect eggs instead of live insects. Upon arrival, stored insect eggs such as cricket eggs can be hatched within 14 days and fed with food waste and/or human waste that was accumulated during the transit to Mars (which takes about 6-8 months). Cricket farming can then be scaled up in tandem with vertical agriculture/ hydroponics. Excess human waste not directed towards cricket farming can be bio-converted by black soldier flies into manure and reintroduced back into vertical agriculture. Because insects have a relatively short reproduction/ life cycle, we don’t have to bring a load of insects but just enough to first maintain a starting population. As an adult female cricket easily lays 100 eggs in its life, it is easy to imagine insect breeding to not only be sustainable but scalable.
The initial amount of eggs to bring depends on the availability of other food source (quantity and quality), number of crew members, and how we plan to transition between the different phase of settlement. It would make perfect sense to bring more if we depend on it as our primary source of protein and bring less if there is enough food brought from Earth for a while.
Here's an Idea: If you bring insects to Mars, for example, is the chitin in insects already available to use, or must a process occur to make the chitin available to be used?
Shiwei Ng: Chitin is present within the exoskeleton of insects and an extraction process needs to occur to make it available for us. After separating the bulk of insect protein from the exoskeleton, it would need to undergo the process of deproteinzation, demineralization (we have chitin at the end of this stage), and deacetylation (we have chitosan at the end of this stage which we used). The processes remove the proteins, minerals, and the acetyl group (which makes it soluble in weak acidic solution, i.e. 1% acetic acid).
There are ways to eliminate the use of chemicals by using enzymes, fermentation treatment, or even obtaining chitin from fungi which does not need to remove protein or minerals.
Here's an Idea: How does, say, a black soldier fly create chitin from waste? And how much chitin can the BSF create? Is the chitin taken from dead flies? Live flies?
Shiwei Ng: Chitin is the main structural component of the cuticle of BSFs, which is present across all instars [developmental stages between two periods of molting in the development of an insect larva]. It can be extracted during the prepupal stage due to its high protein content. Chitin constitutes about 6-9% of the BSF.
Here's an Idea: Can you provide a kind of simplified explanation of how the chitin is gathered, and then how that chitin is brought into the “concrete”-making process?
Shiwei Ng: From exoskeletons of crickets (protein complement) to heterotrophs such as black soldier fly (waste management), chitin can be extracted chemically or through fermentation. Working with chitosan (deacylated form of chitin) which is soluble in weak acidic solution, it is dissolved to form a binder that can be mixed directly with Martian regolith for manufacturing purposes.
What do you think of the idea? Share your questions and comments below.