Development Testing and Analysis of the Integrated Gateway-ESPRIT Bipropellant Refuelling System

The Gateway will be humanity’s first space station orbiting the Moon completed by NASA in partnership with ESA and other US and international partners. The Gateway will provide critical support to sustainable human exploration on the moon through the Artemis program. To enable the Lunar Gateway to complete its mission, on orbit refuelling is essential. The ESPRIT Refuelling Module (ERM) will provide the capability to transfer propellants, MMH and MON-3, through the Habitation and Logistics Outpost (HALO) to the Power and Propulsion Element (PPE). The transfer of these propellants carries known risks and hazards. These hazards include overpressure of the propellant lines during priming sequences between modules and during refuelling pause operations. To support the early system development and to mitigate these risks, a collaborative test program between NASA, ESA and Thales Alenia Space was completed at the Thales Alenia Space test facility in Harwell, UK. This test program integrated fluidic breadboards of the ERM, HALO and PPE modules. The objectives of the test program were to demonstrate and characterise critical performance and transient operations, inform refuelling concept of operations and to calibrate and validate numerical models of the refuelling subsystem in EcosimPro. To support the completion of this final objective a detailed model of the integrated breadboard was developed in EcosimPro and key steady-state and transient test cases were simulated. As an industry first, a National Institute of Standards and Technology (NIST) database correlation for Hydrofluoroether (HFE-7000) was used as a mixed oxides of nitrogen (MON-3) simulant with EcosimPro and European Space Propulsion System Simulation (ESPSS) libraries to result in a more accurate analysis for transient phenomenon such as priming. The test and simulation data showed good agreement validating the model for further system analysis as the ERM design progresses.