Soil and Survival
Worms: The Backbone of Civilization
Why the first Martians will need a bucket of worms more than another rocket
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I have spent forty-one years building things in one of the harshest places on this planet, the Alaska North Slope. It will teach you lessons that no engineering school ever will. Getting to a place is only the beginning. Staying there is the whole job.
That is the part of the Mars conversation that nobody seems to be talking about.
Right now the entire public argument about Mars is transportation. How big is the rocket, how many tons to orbit, how many launches to make the window. It is a very hard problem and there are brilliant people working on it. But it is a delivery problem, and delivery is a truck. Nobody has ever built a town by admiring the truck that brought the lumber.
And I want to be fair to the people doing that work, because it is genuinely getting done. Private enterprise has taken over the hard part. SpaceX is ahead of everyone, Blue Origin is building, China and Japan are moving. These are serious people making real progress, and I am not knocking a single one of them.
But every one of those programs is a transportation program. It doesn't appear that anybody is looking much past the landing. I am not saying nobody is — I am saying it does not appear in the public conversation, and it should. The survival problem takes longer to solve than the rocket problem, because you cannot test a closed food system in a fiscal quarter. Soil takes years to build. Worms take generations to prove out. That work pays dividends if we start it now, and it costs us a decade if we wait until the transportation problem is finished.
So let me ask the question that keeps me up at night. Once the door opens and the first crew walks out onto that rusty gravel — what are they going to eat in year three?
Dirt is not soil
Here is the thing most people get wrong, and I include myself in that for most of my life.
Soil is not dirt. Dirt is ground-up rock. Soil is a living animal.
A single teaspoon of healthy garden soil on Earth holds something on the order of a billion bacteria, several yards of fungal thread, and thousands of protozoa and nematodes all eating each other in the dark.1 That mob is what makes nitrogen available to a root. It is what builds the little crumb structure that lets water soak in instead of running off. It is what fights off the diseases that would otherwise take a crop. Take a healthy field and sterilize it, and you do not have a field anymore. You have gravel.
Mars has gravel. Beautiful, iron-red, perfectly sterile gravel. And it is worse than sterile — the regolith is loaded with perchlorate salts, which are toxic to a plant and toxic to a person.2 That dust is not neutral. It is actively hostile.
You cannot solve that by shipping soil. Do the arithmetic sometime. Topsoil runs somewhere near a hundred pounds a cubic foot. Feeding one adult out of a garden takes a few hundred square feet of bed, and a bed needs a foot of depth to mean anything. That is tens of tons of dirt per person, before you have shipped a single seed, a bolt, or a sandwich. At the price of putting weight on Mars, you would be freighting the single cheapest substance on Earth across a hundred and forty million miles.
Nobody is doing that. Which means the first colony does not import soil.
It grows it.
Which brings me to worms
You cannot ship the soil. But you can ship the machine that makes it, and that machine weighs almost nothing and reproduces itself for free.
A red wiggler is about a gram. A five-gallon bucket holds a couple thousand of them, and under decent conditions a worm population roughly doubles every two to three months.3 Ship one bucket. In two years you have a herd.
And look at what they actually do for you, because it is not one job, it is four:
They convert waste into fertility. Every crew is going to generate garbage — food scraps, crop stalks, human waste, paper, packaging. On a closed station all of that is a disposal problem you have to spend energy on. Hand it to worms and it stops being waste and becomes the input to your farm. That is the whole game in a closed loop: nothing is trash, everything is feedstock for the next thing.
They make regolith into a growing medium. Worm castings are not just fertilizer. Running material through a worm gut coats the particles in mucus and microbes, and that is what forms aggregates — the crumb structure that lets a soil hold air and water at the same time. Dead dust plus organic matter plus worms, run long enough, starts to behave like soil.
They carry the biology. This is the piece I think gets missed. The worm is not really the point. The worm is the delivery vehicle for the bacteria. A worm's gut is a bioreactor, and castings come out with microbial counts far higher than what went in.4 You are not shipping a bucket of animals. You are shipping a live, self-propagating starter culture of an entire soil ecosystem, packaged in a container that feeds and reproduces itself in transit.
They are protein. Nobody wants to say it out loud, but a worm bed is also a standing emergency food supply, and it is a very good one. That may never get used. It is comforting that it is there.
There is no other single organism I am aware of that does all four of those jobs at once, for a launch mass measured in pounds.
What we actually don't know
I am not going to sit here and pretend this is solved, because it isn't, and this magazine has never been in the business of pretending.
Nobody knows what a third of a gravity does to a worm over generations. Nobody has run a worm colony through a nine-month transit with the radiation dose that entails and then had it perform on the other end. We have decent lab work on plants in Mars simulant, and some of it is genuinely encouraging once the perchlorates are washed out and organic matter is added — but simulant is made on Earth, and it is not the real thing.5
Those are answerable questions. They are cheap questions. You could run most of them for less money than a single Starship static fire costs, and to my knowledge, almost nobody is funding them at any serious scale.
That is the imbalance I want this magazine to keep pointing at. We have poured a generation of money and genius into the rocket, and comparatively pocket change into the question of what happens after the ramp comes down.
The unglamorous foundation
My father was a miner. One of his ideas — and we traded a lot of them, we used to call it swapping million dollar ideas — was to tunnel into a mountain, hollow out a room, and put a greenhouse down there under artificial light. Let the rock do the insulating. He never had the money or the time to chase it, but people are doing versions of it now in old mines in Britain and Japan.6 He was thirty years early.
He was also solving exactly the right problem. Not how to get somewhere. How to eat once you are there.
Every civilization in human history has been built on top of six inches of living soil and the fact that it rains. Every single one. We stopped noticing because we have never once had to make it ourselves.
On Mars, we will have to make it ourselves. And when the first Martian farmer stands over the first bed of dark, crumbly, honest-to-God soil grown out of dead red dust, the thing that built it will not have been a rocket.
It will have been a bucket of worms.
From one explorer to another, we appreciate you reading this far. We are excited about what this endeavor brings, and we would like you along for the rest of it.
Come join us. Because we are Star Bound.
John LangEditor
Ideas in Star Bound are published open — take them, build them better. Our open proposal.
A note on where this comes from. I am not a metallurgist, a spacecraft engineer, or a degreed engineer of any kind. But I am a practical one, with more than forty years in heavy industrial construction: welding, millwright work, hydraulics, mining, and thirty-three years of electrical construction and commissioning on the North Slope of Alaska, in a place that punishes anything built wrong. Much of that time I have worked as a field engineer, which means I am the one standing in front of the equipment when the drawing turns out to be wrong, and the fix has to be made on the spot, with what is on hand, and has to work the first time. Anyone who has done that long enough learns that a lot of engineering gets corrected in the field by people with more experience than the people who drew it. That is the eye I bring to these subjects: not what should work on paper, but what actually gets built, and what breaks. The facts I take from other people are footnoted so you can check them and read further. The ideas built on top of those facts are my own, and I would rather see them knocked down by somebody who knows better than left standing because nobody looked.
Sources
- University of Nebraska–Lincoln Extension, Soil Microbes and Their Role in Soil Health (NebGuide G2327) — a teaspoon of soil holding more than a billion bacteria plus yards of fungal mycelium. The same order-of-magnitude figures appear in USDA NRCS soil-biology material. ↩
- Hecht et al., Detection of perchlorate and the soluble chemistry of martian soil at the Phoenix lander site, Science 325 (2009) — 0.4 to 0.6 percent perchlorate by mass at the Phoenix site. Whether that figure holds planet-wide is still an open question; see NASA JPL, Phoenix Mars Team Opens Window on Scientific Process. ↩
- NC State Extension, Wormy Facts and Interesting Tidbits — under good conditions a red wiggler population can double its collective mass in about 60 days. Two to three months is the conservative end of what growers report. ↩
- The bacterial and fungal enrichment of castings relative to feedstock is a standing result in the vermiculture literature; the reference text is Edwards, Arancon & Sherman (eds.), Vermiculture Technology (CRC Press, 2011). ↩
- Wamelink et al., Can Plants Grow on Mars and the Moon: A Growth Experiment on Mars and Moon Soil Simulants, PLOS ONE 9(8), 2014 — the first large controlled trial; the authors themselves flag that simulant may not represent the real soil. Later work by the same group and others added organic matter and dealt with perchlorate separately. ↩
- Growing Underground, Clapham, London — a commercial farm in a Second World War shelter tunnel, described in ScienceAlert, World’s first underground urban farm opens for business in London. The Japanese examples I have seen are press reports and are not footnoted here. ↩
Topsoil density and the general biology of soil structure are standard soil-science figures and are not footnoted individually. The launch-mass arithmetic is my own back-of-envelope.
More from Star Bound
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- Light Is the ThrottleWhat a mine in Idaho and a garden in Alaska taught us about growing things fast — and what continuous daylight does to a plant that never gets to sleep
- Commission It FirstWe have already run phase one. It cost one man 150 million dollars of his own money, and it very nearly killed the people inside.
- Life in the BarrelO’Neill gave us the barrel in 1976 and got very little of it wrong. What he did not finish was the inside — and the standard the inside has to meet isn’t twenty years. It’s forever.
- Send the Robots FirstWhy the road to Mars runs through the moon, and why the first lunar miners will never leave Earth
- Wet the Ground and WaitA passive water generator for the desert, and why we should build one before we need one on Mars
- Send the Refinery, Not the OreWhy the belt gets mined by factory ships, and why that is the one job we cannot run from a chair
- Grind the Asteroid, Print the PartWhy there will never be a steel mill in space, and what replaces it
- Powder or WireThe two ways to print metal, why neither one is ready for the Belt, and the questions somebody has to answer first
- Bones Don't Travel WellThe one problem no rocket solves, and why Gerard O'Neill worked out the answer in 1976
- Blow the Rock Like GlassMy father's answer to how you build something big enough to spin, and the man who worked it out in 1963
- Built for Earth, or Built for Something Bigger?The tools a colony needs are being perfected right now, by people who say they are building them for us
- Mission Watch: September 2026What private enterprise and the agencies actually did this summer, in the order that matters
- The Question I Asked Buzz AldrinIn 1996 I asked the second man on the Moon what part private enterprise would play in space. Thirty years later, the answer is checkable
- A Thousand GaragesBefore there is a printer in space, there has to be a shipyard on the ground, and the shipyard does not have to be in one place
- Sixteen Inches of SteelThe number that breaks the mile-wide barrel, four ways around it, the one we would bet on, and a file you can print tonight
- Launch the Parts, Not the ShipYou cannot launch a habitat big enough to spin. So you launch a shipyard, and you let the robots build it.
- Fish, Salt, or DirtThree ways to feed a habitat, what each one costs you, what each one can't survive, and a question for the reader.
- Thirty Thousand Volts and a Piece of Tin FoilI drove an hour and a half to call a man a liar. He turned on a computer monitor instead, and I have been thinking about it for twenty years.
- A Message in a Bottle, Thrown HardEvery article in this magazine is about how to build something. This one is about how to pay for it.
- The Box Nobody TestedIn 1991 eight people were sealed inside three acres of glass to prove a closed world could keep them alive. It nearly didn't, and the reason was sitting in the walls the whole time.
- Out the Side of the MountainTwenty miles of vacuum tube under a Hawaiian volcano, and a freight train that never comes back down. What a ground-based mass driver would actually take, and why it exits the flank instead of the summit.
- That’s Not a Rocket, It’s a Freight TrainHow I wired the one on my bench in 1994, the one I drew and never built, and why a mass driver runs on railroad logic, not rocket logic.
- Cold, Vacuum, and a Hundred Thousand JointsWhat geosynchronous orbit does to the ten-inch panels in "A Thousand Garages," starting with the question every steel man asks first — and one thing that article got wrong.
- One Press or Ten ThousandElon Musk casts a car underbody in one shot with a machine the size of a house. We proposed ten thousand garages. It turns out we may both be right, on different walls — but nobody knows until somebody breaks fifty panels on purpose.
- Cast It or Print ItThree ways to make a hundred thousand habitat panels. What each one buys you, what each one costs you, and where each one belongs. The first entry in a department that exists to write both columns down.
- Powder or PlateThe garages stay. What's in them changes.
- Refuel It or Strip ItThe graveyard belt is the closest junkyard we've got.
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