Gateway with ESPRIT module right

The ESPRIT refueling module is part of the Gateway’s core structure. The module is 4.6 m in diameter and 6.4 meter in length. It weighs around 10 tonnes on Earth filled with fuel.

The ESPRIT Refueling Module (ERM) has four main functions: transport cargo to the station, provide storage space once docked at Gateway, provide fuel to propulsion system of Gateway (NASA’s Gateway Power and Propulsion Element), and provide a view of space and the Moon through its windows.

The ERM has two main structural elements: the pressurised tunnel where astronauts can float inside (the white cylinder on the right in this picture) and an unpressurised element surrounding part of the pressurised hull.

The pressurised tunnel is a habitable environment used for storage and offering passage between the two docking ports at each end of the tunnel. At launch the ESPRIT module is designed to hold cargo of up to 1.5 tonnes.