In-Space Transfer Vehicle Primary Propulsion
Japanese H-II Transfer Vehicle (HTV)
In support of the first two H-II Transfer Vehicle missions, Aerojet Rocketdyne provided all of the rocket engines aboard the HTV: four model R-4D liquid bipropellant (100 lbf thrust) main engines and 28 model R-1E (25 lbf thrust) reaction control engines. The R-4D engines are primarily used for delta-v raising and orbital maneuvers, while the smaller R-1Es are used for attitude control during docking.
European Automated Transfer Vehicle (ATV)
Aerojet Rocketdyne's model R-4D 100 lbf force class bipropellant main engines are a derivative of the 32 engines flown on the Apollo lunar and service module. They are used for achieving orbit on many geosynchronous satellites and also will be used on the next-generation Orion Service Module. The four model R-4D engines were delivered to the prime contractor, EADS Astrium in Bremen, Germany, for use on the Automated Transfer Vehicle.