Every mission in the solar system needs propellant. Every mission currently carries all of it from Earth at enormous cost and mass penalty. Pro-Pel changes that. A network of asteroid-supplied propellant depots from Earth departure orbit to Mars, fuelling any spacecraft, any propulsion system, any mission profile — from the first depot at Month 4.4 of L4 arrival.
Pro-Pel depots are positioned at every major mission waypoint in the inner solar system. Asteroid-derived propellant at zero raw material cost. No Earth launch required for resupply after the seed ship. Every depot is DRAD-1 autonomous — no crew, no ground operator per transaction.
Pro-Pel stocks every propellant used by any operational or planned spacecraft propulsion system. Chemical, electric, nuclear thermal, and fusion propellants — all produced from asteroid feedstock at L4, zero Earth launch cost. If your mission uses it, Pro-Pel has it.
| Propellant | Production method | Applications | Depots stocked | Availability |
|---|---|---|---|---|
|
Liquid Methane (LCH₄)
CH₄ · bp -161.5°C
|
Sabatier reaction: CO₂ + 4H₂ → CH₄ + 2H₂O. CO₂ from C-type asteroid outgas. Hydrogen from asteroid water electrolysis. | SpaceX Starship (Raptor), Blue Origin New Glenn (BE-4), future Mars ISRU. Primary chemical propellant for all Speculāris FPP boost vehicles. | L4 Primary · NEO · L5 · Mars L4 · Earth Departure | Month 4.4 |
|
Liquid Oxygen (LOX)
O₂ · bp -183°C
|
Water electrolysis from asteroid ice. High-voltage electrolysis powered by L4 mirror array. Co-produced with LH₂. | All bipropellant chemical engines as oxidiser. Raptor, BE-4, Merlin, Vulcain, LE-9, RS-25 and all future engines. | L4 Primary · NEO · Lunar · Mars L4 · Earth Departure | Month 4.4 |
|
Liquid Hydrogen (LH₂)
H₂ · bp -252.9°C
|
Asteroid water electrolysis. Highest Isp chemical propellant. Cryogenic storage requires active refrigeration — provided by L4 solar power. | RL-10 upper stage, J-2, Vinci, LE-5, H-3 second stage, nuclear thermal (NTR) propellant, fuel cell power systems, lunar surface power. | L4 Primary · Lunar · Earth Departure | Month 6 |
|
Hydrazine (N₂H₄)
N₂H₄ · monopropellant
|
From asteroid nitrogen and hydrogen. Asteroid outgas contains NH₃ — catalytic processing yields hydrazine. Month 12 first production. | Spacecraft attitude control, station-keeping, orbit maintenance. Drop-in replacement for existing satellite fleet — no modification required. Every operational satellite in GEO uses hydrazine or MMH variants. | L4 Primary · NEO · Earth Departure | Month 12 |
|
Nitrogen Tetroxide (N₂O₄)
N₂O₄ · oxidiser · NTO
|
Nitrogen from asteroid outgas. Catalytic oxidation of NO. Storable at room temperature — no cryogenic requirement. Hypergolic with hydrazine and MMH. | Orbital manoeuvring system (Space Shuttle OMS), Orion service module, Viking landers, Apollo lunar module descent/ascent engines. Storable bipropellant for long-duration missions. | L4 Primary · Earth Departure | Month 14 |
|
Xenon (Xe)
Xe · ion thruster propellant
|
Extracted from C-type asteroid noble gas fraction. Solar wind implantation over geological time concentrates noble gases in regolith. Cryogenic separation yields research-grade xenon. | Ion thrusters (Hall effect, gridded ion): Dawn, Hayabusa, SMART-1, BepiColombo, all commercial GEO station-keeping, future deep space electric propulsion missions. Isp 1,500–10,000s. | L4 Primary · L5 · Earth Departure | Month 15 |
|
Helium-3 (³He)
³He · fusion fuel · LH-1 harvest
|
LH-1 Lunar Harvester fleet at Shackleton crater. Solar thermal extraction from regolith at 700°C. Cryogenic He-3/He-4 separation. Research grade purity. 37.2 kg/yr initial, doubling every 6 months. | D/He-3 fusion propulsion (FPP-1, FPP-2), fusion power plant fuel, fusion research (QST, NIFS, ITER, private fusion sector), cryogenic applications, polarised neutron sources. | L4 Primary · NEO · L5 · Lunar Gateway | Month 17 |
|
Helium-4 (⁴He)
⁴He · He-3 co-product
|
Co-product of He-3 cryogenic separation. LH-1 harvest yields He-4 alongside He-3. Stored separately. Commercial market: MRI machines, scientific instruments, superconducting magnets, balloon lift. | Pressurant for cryogenic propellant tanks (replaces scarce Earth helium), MRI scanner refills, lab supply, superconducting magnet cooling, helium leak testing. Significant commercial market. | L4 Primary · L5 · Lunar | Month 17 |
|
Water (H₂O)
H₂O · ISRU feedstock
|
Asteroid ice extraction. C-type asteroid 2020 XL5 contains water ice. Volatile extraction via Phase 2 bake programme — hole covers, NPT piping, scuba tank storage. Electrolysed to LH₂/LOX or delivered direct as propellant for nuclear thermal engines or electrothermal thrusters. | Electrolysis feedstock for LH₂/LOX, nuclear thermal rocket propellant (highest Isp ~1,000s), resistojet/arcjet propellant, life support water, radiation shielding, Sabatier process hydrogen source. | L4 Primary · Lunar · Mars L4 | Month 4 |
|
CO₂ / Mars ISRU
CO₂ → CH₄ · Mars atmosphere
|
Mars L4 depot only. Martian atmosphere is 95% CO₂. Sabatier ISRU converts CO₂ + H₂ → CH₄ + H₂O using hydrogen from Deimos water ice or belt delivery. Full CH₄/LOX propellant production at Mars at near-zero cost. | Starship Mars return propellant, any CH₄/LOX engine refuelling at Mars, Mars surface power (CO₂ electrolysis), Mars ISRU demonstrator for future colonisation base propellant independence. | Mars L4 only | Year 5+ |
|
Carbyne Slurry
sp-carbon · experimental
|
Factory 3 Line 3C carbyne synthesis. Experimental high-energy-density propellant candidate. Carbyne combustion enthalpy exceeds diamond. Slurry with LOX forms ultra-high-Isp bipropellant combination under investigation. | Experimental high-Isp chemical propulsion research. ChemLab 1 process chemistry characterisation. Potential future propellant for high-priority boost missions from belt to L4 where mass is critical. | L4 Primary only (experimental) | Year 3 (experimental) |
Pro-Pel serves any spacecraft with any propellant connection standard. No mission is turned away for a hardware mismatch. The Pro-Pel adapter kit covers every fill port standard in current or planned use. C2 Operations drones handle the physical connection — no EVA, no crew, no delay.
Every propellant in the Pro-Pel catalog is manufactured from asteroid feedstock at L4 at zero raw material cost from Earth. The asteroid is the mine. The mirror array is the power source. The factory is the refinery. The cost of propellant in space is no longer dominated by the cost of lifting it from Earth.
Every mission in history has been constrained by the cost of lifting propellant from Earth's gravity well. The rocket equation is unforgiving. The mass fraction of propellant dominates every mission architecture. Pro-Pel removes that constraint.
When propellant is available in space at near-zero marginal cost — manufactured from asteroid feedstock, powered by the Sun — the entire calculus of space mission design changes. Missions that were impossible become routine. Destinations that required enormous launch vehicles become accessible to small, purpose-built spacecraft that refuel on the way.
Speculāris — On the cutting edge.
Pro-Pel opens for business at Month 4.4 of L4 factory arrival. Any spacecraft. Any propellant. Any orbit. The solar system's first open-access propellant network.