Ullage Motor

BACKGROUND

Autogenous pressurization is the use of self-generated gaseous propellant to pressurize liquid propellant in rockets. Traditional liquid-propellant rockets have been most often pressurized with other gases, such as helium, which necessitates carrying the pressurant tanks along with the plumbing and control system to use it. Autogenous pressurization has been operationally used on the Titan 34D, Space Shuttle, Space Launch System, Starship, Terran 1, and New Glenn. Autogenous pressurization is planned to be used on Rocket Lab's Neutron rocket.