Stage 5 – Interplanetary Logistics

SLPA creates a complete, self-sustaining logistics network across the solar system. Rather than relying on chemical propellant production, nuclear reactors, or massive solar farms, SLPA forms a unified ecosystem powered by the RTC (Regenerative Thermal Core), STIP thrusters, and ATRC. This stage explains how materials, heat, and working gases move between worlds to enable continuous, scalable transportation.

1. Orbital Gas Depots

Gas depots act as the central refuelling nodes of the SLPA network. They store:

• Water (H₂O) – for steam/STIP operation and crew needs.
• CO₂ – the primary propellant for thermal and mixed-gas STIP modes.
• O₂ and H₂ – for chemical heating, STIP augmentation, and life support.
• Regolith pellets – for shielding, construction, and momentum exchange.

Each depot functions as a multi-role node: a gas station, warehouse, and thermal power hub for RTC recharging.

2. Thermal Energy Depots

Just as gas depots store propellant, thermal depots store heat. These large orbital RTC units act as slow-cooling, high-capacity energy stations.

When a ship arrives:

• Heat-exchanger lines connect the ship’s RTC to the depot’s RTC.
• Thermal energy is transferred directly and efficiently.
• No large onboard solar arrays are required for deep-space missions.

This system keeps the entire transport network operational—even far from the Sun—through continuous RTC recharging.

3. Ship–Depot Interaction

Each SLPA ship interacts with depots through three independent channels:

• Heat Exchange: RTC recharge for propulsion, thermal management, and crew survival.
• Gas Refill: Water, CO₂, O₂, and optional H₂ blends for the full STIP propulsion spectrum.
• Mass Transfer: Regolith pellets for shielding and construction.

This modular structure enables rapid turnaround and dense traffic through the SLPA corridor.

4. Resource Extraction: Closing the Loop

Depots are supplied from planetary surfaces via the ATRC (Atmospheric and Terrestrial Resource Collection) system, which handles in-situ resource extraction and surface-to-orbit transfer. ATRC is treated as a complementary but independent architecture and will be disclosed in detail in a future patent, allowing SLPA to remain propulsion- and resource-agnostic while fully supporting ISRU-based logistics.

Read the Resource Extraction System →

5. Dropships and Surface Interaction

In low-gravity environments—most notably the Moon—SLPA tugs can natively operate as dropships. Using long-duration hot-gas thrust and locally produced working gas (e.g. lunar O₂), an SLPA vehicle can descend, land, refuel, and return to orbit without requiring a dedicated lander class. This capability allows SLPA vehicles to act as an alternative or primary mass-uplift mechanism for constructing orbital infrastructure, reducing or eliminating reliance on railguns or fixed launch systems during early and mid-stage development. Prepared landing pads, surface refueling stations, and orbital depots transform SLPA vehicles from simple tugs into an integral logistics layer for lifting mass off low-gravity bodies, enabling routine surface-to-orbit freight operations. By implementing this infrastructure, the same system simultaneously enables surface access and bulk mass uplift, solving two fundamental challenges with a single logistics layer.

5.1 ISRU Implications

By enabling routine surface-to-orbit operations in low-gravity environments, SLPA significantly reduces the scope and complexity of ISRU required in the early phases of lunar and small-body development. Rather than requiring a broad, fully featured surface ISRU stack from the outset, SLPA prioritises only the ISRU functions needed to close the logistics loop—primarily working gas production (e.g. O₂), basic regolith handling, and landing infrastructure. More complex ISRU activities, such as metal refining, precision manufacturing, and large-scale processing, can be deferred or relocated to orbit, where cleanliness, thermal stability, and logistics support are more favorable. This sequencing reduces early surface mass, human dependency, and operational risk, while preserving the ability to expand ISRU capabilities later as logistics cadence and infrastructure maturity increase.

6. Global Coverage Across the Solar System

SLPA’s logistic network functions effectively from Earth’s orbit out to Jupiter. Even though sunlight falls to ~4% intensity at Jupiter, RTC units require only trickle charging to maintain operational capability. Combined with orbital thermal depots, this enables:

• Near-continuous operation across the inner and mid–solar system.
• High-efficiency STIP “cruise mode” between planets.
• Greatly reduced dependence on solar farms and nuclear reactors.