One of the many challenges of colonists away from Earth will be construction. Gravity, temperature, atmosphere, and environment will affect the materials and methods we will choose to build future homes on other planets or moons. A new process published in Chem Circularity by Dr. Ning Liu and collaborators of the Hong Kong University of Science and Technology explores alternatives to concrete for houses built on the Martian surface, further paving the way for future extraplanetary colonists.
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Astro Brief is a podcast collaboration between KSMU, the Missouri Space Grant, and MSU's Department of Physics, Astronomy and Materials Science. Hosted by Dr. Mike Reed, Astro Brief focuses on astronomical events, the field of astronomy, and astronomy-related guests. It airs Thursdays at 9:45 am on KSMU.
Transcript
In this episode, we're going to talk about an interesting idea to make houses on Mars. Let's begin by reminding ourselves about the environment on Mars.
The first place to begin is that Mars is 10 times less massive than Earth. That means gravity is only 38% what it is on Earth's surface. Mars also has a very dry surface — though there is ice frozen into the dirt at mid-latitudes — and Mars also has polar ice caps made both of water ice and dry ice — which is frozen carbon dioxide.
And Mars' atmosphere is also 95% carbon dioxide, yet less than 1% the density of our atmosphere. That means no ozone layer — which exposes the surface to dangerous ultraviolet radiation.
Also Mars does not have a global magnetic field like Earth, but it does have magnetic rocks — which indicates that it used to. That magnetic field would have provided protection from charged particles in the solar wind — so there's no water on the surface now — the atmosphere is extremely thin without ozone, and there's no protective magnetic field.
But allow me to read a long quote from an article by D.K. Buckner and A. Mojarro titled An Organic's Forward Approach to Searching for Life on Mars.
They write,
"Geological evidence suggests ancient Mars was more Earth-like and characterized by warmer temperatures, widespread fluvial activity, a thicker atmosphere, and a protective magnetic field shielding the surface from radiation. Habitable conditions continued until cessation of the Martian Dynamo terminated the planetary magnetic shield, leading to solar wind-induced atmospheric erosion and the loss of surface liquid water. Nevertheless, early environments inferred to be analogous to those found on Earth."
Despite all the current drawbacks and considering Mars' intriguing history, Mars has long been a fascination to us Earthlings, and it does have some advantages.
We know there is liquid water beneath the Martian surface in aquifers, it does have some quantity of atmosphere which could be useful for growing plants — which could then provide oxygen — it's not too much colder than Earth — though always below freezing — and the Martian day is only 40 minutes longer than ours.
As such, we have long considered colonizing Mars for our own use.
President Kennedy wanted to send a mission to Mars and in 1989, President George H.W. Bush announced the Space Exploration Initiative to go back to the Moon and then to Mars. Now we have Elon Musk and SpaceX with what's called Mars and Beyond.
Musk's plan is to colonize a million people on Mars making humans an interplanetary society. That's really the whole point of SpaceX's Starship Heavy Lift rockets, and the idea is to make humanity safe by living on two separate planets. So if one of them dies out, we have sort of a backup planet. Not quite as crazy an idea as it sounds, particularly with the recent warnings about AI.
Besides the enormous endeavor it would take to get a million people to Mars, they'd have to live somewhere once they got there, and that's quite difficult.
Firstly, you cannot make concrete on Mars, which requires water and time for it to cure. Water on the Martian surface quickly freezes and then sublimates, breaking up the concrete as it does. That means a process called sintering is required. In that process, the Martian dirt is heated to a thousand degrees centigrade to create useful material, but that requires huge quantities of energy.
But now a new process has been published in Chem Circularity by Dr. Ning Liu of the Hong Kong University of Science and Technology and collaborators using yeast.
Yes, you heard correctly, yeast. The yeast has been genetically modified to create muscle foot proteins — mussels like in oceans, not in your arms. Those proteins act like a glue, allowing the yeast to stick directly on Martian sand. The method also requires a gelatin and with those ingredients — once some material is made — it actually would cure in the lower Martian pressure.
The process does require water, but the genetically modified yeast also contains peptides — sort of like an antifreeze that allow the liquid water to sublimate directly to gas without freezing. The process requires substantially less energy and can also be recycled and reused.
In a prototype material, Dr. Liu's group could reheat it until the gelatin liquefied and then recast it four times before it broke down. However, there are some drawbacks, most notably the gelatin has to be transported to Mars as it can't be made there and the material itself is not airtight.
It would require some sort of internal membrane to keep the air inside, but it is certainly a step in the right direction to having humans living on Mars.