UR-100-MR (SS-17 Spanker) Russian Intercontinental Ballistic Missile
This ICBM was first seen in flight test in 1972. Together with SS-19, which is almost certainly a competitive design to act as a spur and insurance, this extremely formidable missile is a successor for SS-11, and is now installed in many former SS-11 silos. Unlike all previous Soviet missiles known in the West, SS-17 has cold-launch ejection, with great advantage to the silo and also conferring an increase in ultimate range. Compared with SS-11 this missile has similar caliber but much increased length, the first stage being particularly long. Storable liquids are used, and an American model shows fairing ducts past the tanks of both stages (this would not affect cold launching, which used a piston or sabot to blow the missile out). Early testing featured three MIRV warheads, and this is the first Soviet MIRVed ICBM in service. The warhead is estimated to weigh twice as much as that of SS-11, and the Mod 12 missile in operation since 1975 has four heads estimated at over 200 kilotons each (the 1978 DoD Secretary’s Report said 4 x 600 kilotons). Mod 2 has a single reentry vehicle of very high yield which, in conjunction with reported outstanding accuracy, gives SS-17 the capability of backing up SS-18 as a counterforce weapon. Deployment was slower than the Soviet Union could have achieved, but over 70 were operational by August 1978.
Dimensions: Length about 80 feet; diameter about 8 feet 3 inches.
Launch weight: In the order of 143,300 pounds.
Range: Over 6,214 miles.
