the family of engines derives from the leros 1 which was developed and qualified in the 1990s by royal ordnance. the in-space propulsion business was acquired by british aerospace, then had a sequence of owners including american pacific corporation, moog (from 2012) and nammo (2017). the leros engines are made of niobium alloy, which is traditionally used for liquid rocket engines such as the attitude control thrusters of the apollo lunar module. as of 2011, more than 70 leros 1 series engines had been flown successfully.