After someone finally leaves the first footprints on the moon since the Apollo era, seeing the first boots on the Red Planet may sound even more exciting — but where is the astronaut wearing those boots going to take them off and kick back?
Martian habitats made of everything from prehistoric lava tubes to living fungus have been proposed. Some are inflatable, many are 3D-printed, and others could be mistaken for space origami. Now scientists have come up with an idea that is not for the squeamish. Chitin is the second most common polymer on Earth after cellulose, and anyone who has ever peeled a cocktail shrimp or cracked open a lobster has eaten something that produces it. It is the primary material in the shells of arthropods.
The idea incorporates insects being a main food source on the journey to Mars and throughout an extended stay, but if crunching on crickets and other things you’d rather swat sounds nightmarish, think about it. What really are shrimp and lobsters but oversized sea bugs?
“We know that there are several organisms containing chitin that can survive in outer space, in much more challenging conditions than Mars,” Javier Fernandez, who co-authored a study led by Shiwei Ng and recently published in PLOS ONE, told SYFY WIRE. “Tardigrades have a chitin-based exoskeleton, but there are many other examples of fungi and lichens with similar ability. Now we are in the process of finding out how much radiation it can handle.”
Whether those tardigrades that crashed onto the moon actually survived remains unknown, but chances are they haven’t perished yet. These creatures are just about the closest you can get to immortal. Ng, Fernandez and their team want to give Martian habitats the toughness of arthropod exoskeletons while creating a sustainable biolith that uses up food waste instead of creating more useless trash. Uneaten mushrooms count since the chitin in fungi is the easiest to work with. Chitosan, or chitin that has been chemically altered with acetic acid, can be mixed with water and Martian regolith to give extraterrestrial cement some backbone.
“An important aspect of the work, maybe the most important, is the fact that the material is made specifically for Mars, is not a derivation of a technology conceived within the paradigm of Earth,” said Fernandez. “As a result, the material itself has embedded its production within an artificial circular ecosystem supporting a human population, and assuming the lowest energy and simplest chemistry that can be produced within that artificial ecosystem.”
Regolith is already found all over Mars. Perseverence will be crawling over regolith in its search for signs of life, and red dust and rocks are the first thing human astronauts will step on once they touch down. No wonder the stuff of the Martian surface will be the main component of the cement that Fernandez, Ng and their team are developing. Launch costs go up $4,000 for every two pounds you add to your payload. If all that Mars-tronauts bring with them are edible insects and fungi to sustain them during the journey, and then recycle those shells into the dirt and rocks that are already there after landing, the savings are astronomical.
Fernandez envisions the chitin cement being used in conjunction with parts made of other materials to put together an entire Martian habitat or complex. Think inflatable habitats and even parts of the spaceship that are no longer needed once it arrives on Mars. You just have to ditch any preconceptions about what would work on Earth, where it would be subject to Earth’s gravity and other conditions specific to our planet. Mars has only a third of Erath’s gravity and its atmospheric pressure 100 times less. While the team was able to make a superstrong wrench out of the chitosan-regolith cement, which came just short of the strength of iron, would you really need an iron substitute for Mars?
“We developed this technology because we work on a transition to a sustainable manufacturing paradigm on Earth, based on bioinspired manufacturing,” Fernandez said, “but the technologies for doing that are the same ones that would allow us to become an interplanetary species.”