Martian Regolith from Arcadia Planitia – First‑Generation Simulant for Early Colonies
“If we want SpaceX’s first crew to plant salad on Sol‑30, the seeds need to meet the dirt before the rocket ever leaves Earth.”
Why Arcadia Planitia?
- Chosen landing zone – Musk & co. favour Arcadia because it’s flat like a parking lot and sits just below datum (–3 to –4 km), trimming velocity on landing burns and leaving plenty of solar hours.
- Ice in the backyard – Ground‑penetrating radar shows a continent‑sized ice sheet a metre or two beneath the surface. Basiacally a free water and radiation shielding.
- Starter pressure, but not too much – Ambient pressure hovers around 7–8 mbar: lower than Hellas, but enough to take the edge off greenhouse wall forces once you inflate to 200 mbar.
- Focus – rapid‑cycle crops and nursery stock: lettuce, radish, wheat, dwarf tomatoes. Trees come later; here we care about speed and scalability.
Mixing Arcadia Planitia simulant in 11 minutes
The basalt problem
A follow‑up clip shows me burning an afternoon hammering 10–15 cm basalt chunks into 0.1-1 cm gravel – and still nowhere near the 0.1–0.3 mm dust that dominates Martian regolith. Buy pre‑milled basalt or rent a mortar grinder. Don’t waste your time.
Recipe
- Basalt dust (50 %) – opt for 0.1–0.3 mm. The video shows why.
- Quartz sand (25 %) – 0.4–0.8 mm adds skeleton and SiO₂.
- Red Fe₂O₃ pigment (10 %) – iron + the iconic colour.
- Dolomite flour (8 %) – CaCO₃ + MgO, buffers pH.
- Gypsum (CaSO₄, 3 %) – matches Martian sulfate load.
- Epsom salt (MgSO₄, 2 %) – extra Mg and sulfate.
- Bentonite clay (2 %) – water retention.
- Coarse basalt chips (trace) – 1 cm stones for realism/aeration.
- NaCl (≤ 1 %) – optional trace chlorides; skipped in this batch.
Total mass ≈ 1 kg. Cost ≤ 5 USD. Build time ~30 min if you buy the basalt dust.
Full Composition Table
| Component | Weight % | Role |
|---|---|---|
| Basaltic Lava Rock | 50 | Major silicates & mafic oxides |
| Quartz Sand | 25 | Silica, aeration |
| Fe₂O₃ Pigment | 10 | Iron source, colour |
| Al₂O₃ / Kaolin | 7 | Secondary aluminium |
| CaCO₃ | 5 | pH buffer, calcium |
| MgO / Dolomite | 3 | Magnesium, additional buffering |
| Sulfate Salts (MgSO₄ + CaSO₄) | 5 | Sulfates, Mg, Ca |
| NaCl | 0.5 | Trace chlorides, ionic charge balance |
| Bentonite Clay | 2 | Water-holding capacity |
| Target pH | 8.3 | Matches in-situ data |
Mental hygiene: why dirt equals sanity
Plants aren’t just calories; they’re a piece of Earth for the brain. A park‑size greenhouse under a thin sky beats grey walls and red dust for crew morale. That’s why even this fast‑crop simulant matters – it seeds the psyche as much as the soil.
Arcadia vs. Hellas in one breath
| Parameter | Arcadia Planitia | Hellas Basin |
|---|---|---|
| Elevation | –3 km | –7 km |
| Surface Pressure | 7–8 mbar | 11–12 mbar |
| Ice Availability | High (shallow subsurface) | Moderate |
| Greenhouse Focus | Short-cycle annuals | Long-lived trees |
| Simulant Grain Size | Coarser basalt preferred | Finer, clay-rich |
| Stress on Dome Walls | Higher | Lower |
Ingredient Cheat-Sheet
| Ingredient | Quickest source |
|---|---|
| Basalt dust | Garden store “rock dust” |
| Quartz sand | Pool filter medium |
| Fe₂O₃ | Concrete pigment – red |
| Dolomite flour | Garden lime (dolomitic) |
| Gypsum | Drywall scraps, plaster |
| Epsom salt | Pharmacy garden aisle |
| Bentonite | Unscented cat litter |
References
- Video tweet – process: https://x.com/i194wisp/status/1938838168666808362
- Video tweet – basalt crushing: https://x.com/i194wisp/status/1934200322416632178
- Soil sheet: https://docs.google.com/spreadsheets/d/1p6y9mfRsjVSnz9jFGhxnw41mjvcu-vK6_ELHifunWNg#gid=1184354963
- Soil Ingredients sheet: https://docs.google.com/spreadsheets/d/1p6y9mfRsjVSnz9jFGhxnw41mjvcu-vK6_ELHifunWNg#gid=946184608