Ganymede Subsurface Initiative — Natural Sciences Museum

Astrobiology · Planetary Science · Interactive Exhibit

Mission: Ganymede

Subsurface Life Initiative — Jupiter System · Sol

Ganymede, Jupiter's largest moon, conceals beneath 800 km of ancient ice a vast subsurface ocean heated by hydrothermal vents. This exhibit simulates a hypothetical terraforming mission to seed that ocean with microbial life — and ultimately crack the ice shield to establish a breathable atmosphere. Your home laboratory participates directly. Real measurements from kitchen experiments feed live into the mission simulator.

Exhibit C-07b · Visitor Lab Programme

Replicate Ganymede — Home Microbiology Protocol

Sulfate-reducing bacteria as an analog for subsurface ocean chemosynthesis

MATERIALS — ~$60 TOTAL

Chemicals

Sodium sulfate (Na₂SO₄)	pool supply, ~$10
Ferrous sulfate (FeSO₄·7H₂O)	garden iron, ~$8
Sodium bicarbonate	baking soda, $2
Yeast extract (nutritional yeast)	Bragg's, ~$8
Sodium lactate 60% syrup	Modernist Pantry, ~$12
Ascorbic acid powder (Vit C)	reductant, ~$6
Sodium thioglycolate (optional)	Sigma, ~$15

Equipment

Ball mason jars (pint, wide mouth)	$12 / 12-pack
Disposable syringes 10mL + blunt tips	$10
pH strips	$7
Pressure cooker (or boil sterilize)	optional

Inocula (free): Scrape the black layer just beneath the surface of stagnant pond mud, ditch sediment, or marsh soil. The black colour is already FeS — you have the right organisms.

POSTGATE'S MEDIUM C — 1 LITRE

          KH₂PO₄           0.5 g

          NH₄Cl            1.0 g

          Na₂SO₄          4.5 g

          CaCl₂·2H₂O      0.06 g

          MgSO₄·7H₂O      0.06 g

          Na-lactate 60%   7.0 mL ← electron donor

          Yeast extract    1.0 g

          FeSO₄·7H₂O      0.004 g

          Ascorbic acid    0.1 g  ← reductant

          NaHCO₃          0.5 g

          dH₂O to 1 L · pH 7.0–7.2

PROCEDURE

Mix all ingredients. Bring to boil, simmer 5 min to drive off O₂.
Dispense 50 mL per mason jar while still hot. Seal tightly.
Autoclave or pressure-cook 121 °C / 15 min. Cool to room temp.
Inoculate 5–10 mL pond mud through a small hole in the lid, reseal with foil + tape.
Incubate at room temp (25 °C) or refrigerator (4 °C) for psychrophile analog.

✓ POSITIVE

Black precipitate (FeS) + rotten egg smell (H₂S) within 1–2 weeks

✗ NO RESULT

Brown or clear media — check seal, pH (needs 6.8–7.4), inocula source

Ganymede analog note: Run a parallel jar at 4 °C with +50 g/L NaCl (brine proxy). Slower growth, same endpoint. This is the closest home-lab approximation of the subsurface ocean chemistry.

Safety: H₂S is toxic — work near ventilation, keep jars sealed. Autoclave all cultures before disposal.

Phase II — Once SRBs confirmed: add sealed headspace vials, N₂/CO₂ cylinder, and rice paddy sediment inocula to attempt methanogenesis (3–4 weeks).

Play the Mission Simulator →

Ice Cracking Progress

Turn 1

          Cards played: 0
        

          Phase progress: 0/4
        

          Nuclear incident · Boston Dynamics droids · Magnetic storm launch · Augusta → Ganymede
        

Sourdough / Yeast

Fermentation → CO₂, organic acids

Egg + Vinegar

Acid bath → H₂S analog, pH drop

Algae / Aquarium

Photosynthesis → O₂ production

Iron Nail + Water

Oxidation → Fe cycling, pH shift

Compost / Soil

Mixed decomposition → CH₄, N₂ cycling

Sourdough starter — mix flour + water, leave uncovered 24h. Bubbles = CO₂ from yeast + bacteria. pH drops as lactic acid builds.

Egg in vinegar — vinegar dissolves shell over 24h. H₂S smell = sulfur chemistry analog. Measure pH of vinegar before + after.

Rusty nail jar — submerge iron nail in salt water. Rust (Fe₃O₄) forms over days. pH rises as Fe²⁺ oxidizes.

Algae culture — aquarium water in a jar + light. Oxygen bubbles from photosynthesis. CO₂ drops as algae consume it.

🪙 VOTIVE Token Donation