The OMS consists of two pods mounted on the orbiter's aft fuselage, on either side of the vertical stabilizer.[1] Each pod contains a single AJ10-190 engine,[3] based on the Apollo Service Module's Service Propulsion System engine,[citation needed] which produces 26.7 kilonewtons (6,000 lbf) of thrust with a specific impulse (Isp) of 316 seconds.[3] Each engine could be reused for 100 missions and was capable of a total of 1,000 starts and 15 hours of burn time.[citation needed]