How the Safeguard worked
The Stanley R. Mickelsen Safeguard Complex consisted of four elements: the Perimeter Acquisition Radar (PAR) complex near Concrete, North Dakota; the Missile Site Radar (MSR) complex 12 miles south of Langdon, North Dakota; and the four Remote Sprint Launch (RSL) sites clustered within 20 miles of the MSR. The fourth element, the Ballistic Missile Defense Center (BMDC) in Colorado, was the only component of the SRMSC located outside of North Dakota. The BMDC was the highest echelon of command and control in the Safeguard system. The BMDC integrated the Safeguard within the North American Air Defense Command, and allowed the Commander of the Continental Air Defense Command (CONAD) to exercise operational command of the Safeguard system.
The defensive Sprint and Spartan missiles were technological marvels. However, the centerpieces of the Safeguard System were the tracking radars and associate computers that rapidly sorted the incoming data and provided instructions to the interceptor missiles.
The largest of Safeguard's structures, the Perimeter Acquisition Radar Building (PARB), consisted of a huge phased-array antenna mounted on a sloped surface facing due north.
The PAR was capable of identifying and tracking incoming missiles at ranges up to 2,000 miles. Unlike a conventional "moving" radar antenna, the PAR's "phased-array" antenna incorporated 6,888 elements, each sending a pulse that would bounce off an incoming target coming over the North Pole. Through comparison of the reflected signals received back from the incoming object, trajectories were computed and this information was passed to the Missile Site Radar (MSR). To operate the PAR, an Army Surveillance Battalion of about 400 personnel would be required to man a three-section watch.
The 470-acre MSR site housed the shorter-range missile control radar and nearly half of the Safeguard system's defensive Spartan and Sprint missiles.
Located in a pyramid-shaped building, the site's phased-array radar had over 20,000 elements distributed equally between its four faces. Using the radar data supplied by the PAR, the MSR located and tracked incoming missiles, computed intercept trajectories, and launched and guided the Spartan and Sprint missiles to their targets. Operatmg the MSR required a staff of 800 soldiers and civilians.
The Safeguard system's defensive missiles were divided between five facilities: the MSR and the four RSLs. Each RSL deployed between 12 and 16 Sprint missiles. The sites, which were all located withing a 20-mile radius of the MSR, were under the operational control of that radar facility.
The Spartan, with a range of nearly 500 miles, was designed to intercept the incoming missiles well outside the earths atmosphere and destroy them with a multimegaton nuclear warhead.
Anticipating that some incoming warheads could slip by the Spartan interceptions and enter the atmosphere over North America, a "layered-defense" provided for a last-ditch defense in the form of the Sprint missile. Built by Martin Marietta, the Sprint was designed to operate at hypersonic speeds within the earth's atmosphere. Sprint's skin could sustain heat greater than that produced by its own rocket motor. Like Spartan, the two-stage Sprint carried a nuclear warhead.