Making Synthetic Martian Dirt
Spring 2019 | By Bree Watson聽鈥�04
Imagine a big, metal machine, similar to a food processor. But instead of shredding cabbage for coleslaw or pureeing chickpeas for hummus, it鈥檚 pulverizing rocks and minerals to make out-of-this-world dirt.
This is a familiar scene for Kevin Cannon, a researcher who founded the nonprofit , an extension of . Cannon and his team of undergraduate students crush, sieve and carefully combine pure minerals to create research-grade聽simulants that replicate the physical, chemical and spectral makeup of soil on the moon, Mars and asteroids.
鈥淏efore humans ever set foot on Mars, scientists need to perform a lot of experiments,鈥� says Cannon. 鈥淲e need Martian soil to do that.鈥� Even though NASA has landed multiple rovers on our neighbor planet, they are years away from ferrying even a small amount of material back to Earth. In the meantime, researchers prefer to use soil simulants like those made by Exolith Lab聽because they can be produced in large quantities with consistency.
Here鈥檚 the scoop on Mars simulant:
Not-so-secret Recipe
Mars Global Simulant (MGS-1) is made up of 11 minerals and non-crystal materials, including聽plagioclase and basaltic glass. Small amounts of ferrihydrite and hematite provide the soil鈥檚 signature reddish hue. The team recently returned from a trip to Montana, where they gathered more than two tons of pure silicate rock from the Stillwater Mine.
Analyze This
NASA鈥檚 Curiosity rover, which landed on Mars in 2012, used X-ray technology聽to analyze soil samples taken from the Rocknest site in the Gale crater. This is the basis for Cannon and team鈥檚 MGS-1 recipe.
Organic Matters
鈥淎 lot of [researchers] are interested in plant growth,鈥� says Cannon. 鈥淎nd it turns out if you try to grow plants with just the default simulant [that we produce], they will not grow. There鈥檚 no organic carbon, no nutrients. And the particle size is too coarse 鈥� like sand.鈥� Cannon says that to be able to grow plants, the soil will likely need to be sifted and supplemented, perhaps with clay found on a different part of Mars or enriched with help from common earthworms.
Building Blocks
鈥淭here鈥檚 also a lot of interest in making building material,鈥� says Cannon. Researchers are developing 3D printers that use simulants as ink to create bricks, tools and other objects. Other engineers are using a high-pressure hammer to smash the simulant and form small but strong blocks that do not require a binding agent.
A Ton of Interest
At $20 per kilogram of MGS-1, the price is within reach for fans of the red planet 鈥� however, the simulated interstellar soil is only available to space agencies and other researchers. To date, the largest request for Mars and lunar simulants has been for 1,000 pounds, which was ordered聽by NASA.