Technology of In-Orbit Propellant Refueling of China Space Station

Propellant refueling is of great significance for improving the lifespan and benefits of large spacecraft. The core module and the cargo spacecraft in China Space Station (CSS) adopt a propellant refueling technology based on gas recycling and pressure-fed schemes. The core module uses compressors to pump the pressurized gas in the gas chamber of its tanks back to high-pressure gas cylinders, and the cargo spacecraft utilizes the pressure difference between the tanks of both sides to transfer propellants to the tanks of the core module by the pressure-fed scheme. The propellant refueling requires close cooperation between the core module and the cargo spacecraft. The process of in-orbit propellant refueling between both sides is divided into five stages, namely, state setting, leakage detection of pipelines, fuel-tank refueling, oxidant-tank refueling, and state recovery. The ground flight control personnel control the whole refueling process step by step. The faults during the in-orbit propellant refueling are handled through autonomous or ground handling.