On Martian Regolith

The living harmony of soil

On Earth, the word “soil” encompasses a vital entity composed of a number of symbiotic organisms.

There is a microcosmos contained within soil, a menagerie of bacteria, algae, fungi, protozoa, nematodes and earthworms, a wealth of minerals and gas and water. The combination of these elements is what makes soil a dynamic composite capable of sustaining life.

Like soil, the human body is also a composite of smaller pieces. In truth, our bodies are less “human” than they are bacteria and water. Or perhaps it is this amalgamation of smaller living organisms which makes us human.

On Mars, the soil is inert, and often poisonous to life due to the high amount of perchlorates. There are no microbes, no thriving and vital organic matter which could support the growth of something as demanding as a growing marigold seed. Martian soil is called regolith, mostly to distinguish it from rocks. A sample has not yet been successfully brought back to this planet, but Martian regolith has been studied remotely through the use of Rover technology. Nothing can grow in regolith, unless it is mixed with living, vital earth.

On Earth, scientists make regolith simulant to be as similar to Martian dirt as possible. Texture, chemical composition, and grain size are all identical to samples studied by Rovers inside Martian craters. This means the powder I’m about to use for planting marigolds is lethally soft. If inhaled over long periods of time, tiny-grained regolith can cause grievous harm to human lungs.

I unscrew the cap on the glass vial and pour out a palm-sized amount.

I run my fingers through the fine dust. It’s dry and powdery, like the wings of a butterfly the color of old blood. When I push a finger into it, the tip sinks easily.

I show Ethan how to fill his pot with potting mix. I go fast because I don’t want him handling the regolith for long. We pour in the ashy substance, which feels like adding poison to this mixture of dark, spongy earth. We each plant several porcupine-quill marigold seeds a fingertip deep.

I tell Ethan to keep the soil and regolith amalgam damp, and to put a piece of saran wrap on the top of his pot to encourage seed germination through concentrated heat and light. Ethan looks like he is paying attention to anything but me when I tell him this. I have come to recognize this is when he is listening intently to what I say.

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On a night with no moon, nearly three weeks ago, I sowed nine marigold seeds in a mixture of rust-colored Martian dust and loamy potting soil. I wasn’t sure if the salt and chlorine content in the regolith would poison the seeds.

Today, there are tender green sprouts straining joyously toward the sun.