Overview
This master thesis assessed whether a resource-enabled Enceladus mission using Water Electrolysis Propulsion could be technically plausible at early feasibility level. The study was part of the ENCORE mission concept, short for ENceladus Chemical Observation & Resource Extraction.
The work followed an early Phase 0/A systems engineering approach. Candidate subsystem concepts were identified from literature, evaluated with first-order engineering calculations, and compared through weighted trade studies. The analysis covered ISRU, water purification, electrolysis, electrical power generation, thermal control, and nuclear propulsion alternatives.
The final result is not a validated spacecraft design. It is a feasibility-level architecture showing how local water resources, electrolysis, fuel-cell operation, and repeated lander sorties could increase the scientific return of a future Enceladus mission.
Mission Concept
The resulting ENCORE concept uses an orbiter and lander architecture. After transfer to Saturn and insertion into the Enceladus mission phase, the orbiter remains in orbit to support remote sensing, communications relay, docking, recharge, and propellant production. The lander descends to the surface, performs science operations, harvests local ice, and returns to orbit after a limited surface campaign.
After docking with the orbiter, the collected water is purified and split into hydrogen and oxygen. These products can then be used for propulsion and for a lander fuel-cell system. This creates a circular mission concept: the lander can return to orbit, recharge, refuel, descend again, and investigate multiple sites instead of being limited to a single landing location.
ISRU and Water Processing
Surface ice harvesting was selected as the preferred ISRU baseline. Plume and E-ring collection were considered, but surface ice offered more controllable access to usable water. An auger-drill concept was preferred over a heated dome because it gives more predictable material acquisition and mechanical control, although both concepts remain immature for the Enceladus environment.
Because Enceladus ice cannot be treated as pure water, the thesis proposed a preliminary purification chain before electrolysis. The concept includes optional freeze distillation, liquefaction and storage, microfiltration, reverse osmosis, degassing, activated carbon, electrodeionization or mixed-bed ion exchange, and inline quality monitoring. The goal is to remove volatile species, salts, particulates, organics, and ionic contaminants before feeding water into the electrolyzer.
Electrolysis Study
The electrolyzer analysis compared low-temperature electrolysis, high-temperature electrolysis, and thermochemical water-splitting concepts. High-temperature systems such as SOECs can offer efficiency advantages when waste heat is available, but they introduce major penalties in operating temperature, lifetime, integration complexity, and thermal management.
For the current mission baseline, capillary-fed electrolysis was selected as the preferred concept. Its lower operating temperature, simpler spacecraft integration, and better suitability for microgravity operation made it more attractive than high-temperature electrolysis for the ENCORE architecture.
Power System Findings
Power availability was one of the dominant constraints of the mission. Radioisotope power systems are technically attractive for the outer Solar System, but the non-RTG baseline assumed an ESA-led architecture using solar arrays on the orbiter and a fuel-cell-based power system on the lander.
These values define the power basis of the circular mission concept and should be presented as preliminary sizing results, not final design values.
- 180 m2 orbiter solar array area
- Approximately 253 kg solar array mass
- 610 W end-of-life orbiter power
- 31.4 kg water reactant feedstock for the lander fuel-cell system
- 100 W lander fuel-cell power
- 25 days surface operation time
- Approximately 9.8 days minimum orbital time for water splitting and recharge before the next surface phase
Thermal Control Findings
The thermal analysis considered both the cold Enceladus environment and the hot Venus flyby environment during the interplanetary transfer. The proposed thermal control system uses established spacecraft technologies, including multi-layer insulation, heat pipes, radiators, heaters, warm electronics cavities, and the high-gain antenna as a sun shield.
At feasibility level, no fundamentally new thermal-control technology was identified as necessary. However, the model remains simplified and should later be replaced by a detailed transient spacecraft thermal analysis.
Nuclear Propulsion
Nuclear thermal propulsion and nuclear electric propulsion were considered as possible alternatives or future enhancements. Both could improve transfer performance or mission flexibility, but they were not selected for the present ENCORE baseline because of maturity, integration, and ESA-related constraints.
Key Contributions
- Developed the EPS, thermal, ISRU, purification, and electrolysis feasibility assessment for the ENCORE concept.
- Compared ISRU acquisition options and selected surface ice harvesting as the preferred baseline.
- Proposed an Enceladus-specific water purification chain for electrolysis feedwater.
- Compared low-temperature, high-temperature, and thermochemical water-splitting options.
- Selected capillary-fed electrolysis as the preferred baseline electrolyzer concept.
- Sized the feasibility-level non-RTG power concept using large orbiter solar arrays and a lander fuel-cell system.
- Assessed thermal feasibility for Enceladus operations and Venus gravity-assist phases.
- Evaluated nuclear propulsion as a non-baseline future option.
- Identified the main technology gaps for future development.
Limitations
The study is an early feasibility assessment. Most analyses are based on literature values, simplified models, first-order calculations, and preliminary trade studies. Major uncertainties remain in the properties of Enceladus surface ice, achievable collection rates, water purification requirements, electrolyzer lifetime, subsystem coupling, and the structural and operational feasibility of very large solar arrays at Saturn distance.
