Re-Usable Nuclear Lunar Spacecraft

The transition to sustainable lunar exploration necessitates the development of high-thrust, reusable propulsion systems that decouple mission duration from Earth-sourced mass dependencies. This article presents the design for a Re-Usable Nuclear Lunar Spacecraft based on an Accelerator-Driven System (ADS) reactor core. By leveraging the nuclear core architecture I proposed earlier, the propulsion system maintains a stable thermal output, delivering high-temperature energy through a monolithic Tungsten shell and a secondary Helium loop. This vehicle utilizes Liquid Oxygen (LOX) as a standardized propellant, facilitating integration with lunar In-Situ Resource Utilization (ISRU) systems while bypassing the structural and storage penalties associated with low-density Hydrogen fuel. The spacecraft is configured as a modular assembly launched via heavy-lift vehicles and integrated in low Earth orbit, prioritizing mechanical simplicity and structural stability for lunar landing. This architecture establishes a closed-loop logistics cycle that utilizes oxygen extracted from lunar regolith to fuel return trajectories, significantly reducing the mass requirements for Earth-to-Moon deployment.

Reactor and Core Design

The propulsion system centers on a 150 MeV Accelerator-Driven System (ADS). The core consists of Depleted Uranium (U-238) fuel elements housed within a monolithic Tungsten shell. This configuration utilizes localized high-energy multifragmentation, maintaining a consistent thermal output of 150 MW. A secondary Helium loop serves as the heat transfer medium, isolating the reactor core from the propellant stream to ensure structural longevity and prevent chemical contamination of the fuel pins.

Propellant and Thermodynamic Cycle

To ensure operational safety and simplify logistics, Liquid Oxygen (LOX) is utilized as the universal propellant. Standardizing on LOX eliminates the risk of hypergolic or explosive contamination associated with transitioning between Ammonia and Oxygen in common tankage. The Helium loop transfers thermal energy to the LOX, heating the gas to a nominal operating temperature of 1500 to 1600 degrees Celsius before expansion through the nozzle. While the molecular weight of Oxygen (M=32) results in a lower specific impulse compared to Hydrogen-based systems, the abundance of lunar-sourced Oxygen offsets the mass-efficiency penalty through in-situ replenishment.

Modular Architecture and LEO Assembly

The vehicle is assembled in Low Earth Orbit (LEO) via modular integration. The core stage, containing the reactor and primary propulsion hardware, is launched via Falcon Heavy. Four auxiliary modules are strapped around the core stage: two dedicated LOX tanks, one payload module, and one multifunctional support/mining module. This radial configuration provides a wide structural base for landing stability and ensures the reactor nozzle maintains sufficient ground clearance of at least two meters.

Landing Dynamics and Stability

The landing system utilizes a four-point contact geometry consisting of three stationary legs and one adjustable hydraulic strut. This variable-length strut compensates for surface irregularities, allowing the vehicle to achieve a perfectly level orientation on uneven lunar terrain. The wide footprint created by the four strapped-on modules ensures the center of mass remains within the stability polygon during high-thrust descent and landing maneuvers.

Lunar Surface Operations and ISRU

Upon landing, the support module detaches from the main assembly. This module is equipped with a wheeled drivetrain and a towing mechanism, allowing it to move the payload module to its final destination. Once the payload is delivered, the support module returns to the rocket to initiate In-Situ Resource Utilization (ISRU). It collects loose lunar regolith and feeds it into the thermal extraction chamber integrated with the reactor core. Utilizing the 150 MW thermal output, Oxygen is extracted from the silicate minerals via direct thermal reduction. An onboard liquefaction system converts the gaseous Oxygen into LOX, which is then pumped back into the primary tanks.

Ascent and Logistics Cycle

For the ascent phase, the payload remains on the surface, and the support module reattaches to the core. The return vehicle operates as a four-module assembly, optimized for a single-stage return to Earth orbit. Once in LEO, the depleted tanks are swapped for fresh LOX modules via automated docking. This cycle allows for repeated lunar deployments using a single nuclear core, significantly reducing the cost of long-term lunar logistics by eliminating the need for Earth-sourced propellant for the return leg.