If we ever hope to build a base, a city, or a full-fledged colony on another world, the first steps are to build structures that can support human existence. The Moon is the closest option, but has many limitations: its gravity is greatly reduced, it has practically no atmosphere at all, and nearly all of the resources humans would need must be brought from Earth. Mars is a little more interesting, with substantial reserves of (solid and gaseous) water, a different mineralogy from Earth, and a thin but meaningful atmosphere: the eighth thickest in the Solar System, just one spot behind Earth.
Importantly, Mars is a sand-rich world, and with sand, an interesting possibility arises as far as construction materials go: concrete, with sand serving as an aggregate. In the past, studies have shown that the type of sand found on Mars is made of a very different composition than sand on Earth, and with a different grain size as well. If one were to try to make concrete using conventional means out of Martian sand, a problem arises: it winds up with large numbers of porous voids within it, making the concrete structurally weak.
Back about a decade ago, a new method was devised for making Martian concrete, but a novel key ingredient was required: sulfur, in its pure form and in large quantities. With NASA’s Curiosity rover recently finding pure, elemental sulfur on Mars for the first time, the prospect of building, cities, and even larger structures on Mars suddenly falls into the realm of possibility. All of the necessary ingredients are now known to copiously exist on the red planet.
The Sphinx of Giza next to the Pyramids in Egypt, as photographed in 2006. The oldest surviving Pyramids date back nearly 5,000 years, and are the largest, oldest surviving human-created monuments. The Pyramids are an early example of the use of concrete: the oldest building material and the most commonly used building material on Earth, even after more than 8000 years of history.
Here on Earth, concrete is one of the most ancient building materials that’s still in widespread use today. In what is now the middle east, people discovered that by mixing lime with sand, stone, and water, a hard, sturdy, and naturally waterproof material would be created. When it dried and cured, it was useful for creating underground water storage systems (cisterns) and foundational structures (floors) for homes and communities.
Concrete was an essential material used in construction throughout history, including in the building of Egypt’s famed pyramids. Advances in which materials were mixed in with the concrete led to harder, sturdier versions of concrete, which in turn led to the ability to construct larger, more complex structure that could bear more weight. Today, more than 8000 years after the earliest version of it was first developed, concrete remains the most widely-used building material on planet Earth.
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