Abstract: The traditional chemical propulsion and electric propulsion have different characteristics and application ranges. The chemical propulsion has a thrust range from ~mN to ~N. In comparison with the electric propulsion, it has the characteristics of high thrust and wide thrust range. The electric propulsion can obtain a maximum specific impulse of thousands of seconds and a minimum thrust of ~μN. However, there are limitations for those two modes, and some complex space missions are difficult to be completed independently by any of them. The dual-mode propulsion system includes both chemical mode and electric mode, and has the characteristics of high specific impulse and wide thrust range, which can improve the flexibility of the spacecraft mission. Monopropellant chemical propulsion paired with ionic liquid electrospray propulsion has received the most attention recently. The principle and characteristics of the monopropellant-electrospray dual-mode propulsion system are introduced. The research status of dual-mode propulsion is summarized, and the existing problems and challenges are analyzed.

Key words: dual-mode propulsion, chemical propulsion, electric propulsion, dual-mode propellant, ionic liquid