A reaction propulsion device in which a first feed circuit for feeding a main thruster with a first propellant includes a branch connection downstream from a pump of a first turbopump, which branch connection passes through a first regenerative heat exchanger and a turbine of a first turbopump, and in which a second feed circuit for feeding the main thruster with a second propellant includes, downstream from a pump of a second turbopump, a branch-off passing through a second regenerative heat exchanger and a turbine of the second turbopump. At least one secondary thruster is connected downstream from the turbines of the first and second turbopumps.