The 'Sprint' ABM missile - Martin-Marietta and AT&T

INHO the most interesting small missile system ever invented/constructed by man.
"The Sprint was a two-stage, solid-fuel anti-ballistic missile, armed with a W66 enhanced radiation thermonuclear warhead(eg. a 'neutron bomb"). It was designed as the short-range high-speed counterpart to the longer-range LIM-49 Spartan as part of the Sentinel program. Sentinel never became operational, but the technology was deployed briefly in a downsized version called the Safeguard program. The Sprint, like the Spartan, was in operational service for only a few months in the Safeguard program, from October 1975 to early 1976. A combination of high costs, congressional opposition, and questionable efficacy resulted in a very short operational period."
(wikipedia)
The Sprint was a two-state missile, which was first shot out of its silo by a powder charge, and then the first stage ignited: burning for only about 1.5 seconds, this solid-fueled rocket motor accelerated the missle at over 100 G's (!), burned out and then the second stage ignited. At this point due to air friction, the surface of the missile itself was hotter than an acetylene welding torch, and yet the ground control radar needed to penetrate this high-temperature plasma, and still communicate with the missile. AT&T designed this system and the computers and support needed to do so: a superlative technical achievement...
The supporting radar systems -- to communicate with the missile in flight -- needed to project and maintain a radar beam of more than One Million Watts (1MW), in a focused direction of less than one second of arc, and instantaneously upgrade the aiming and timing of this radar beam, to maintain communication.
So, all in all, your AT&T-enabled IPhone is multiple orders of magnitude, more pathetic. :)
The linked film shows the Sprint in actual operation: the first part (where it is launched) is shown in 1/5 slow-motion -- where the missile is ejected out of its silo and the first stage is ignited -- otherwise it would not be very visible.
The second part is in real-time: yes, it really is THAT FAST.
As mentioned, this weapon used an 'enhanced radiation' warhead of still-classified design (a 'neutron bomb') to attempt as a last-minute intercept of an incoming re-etnry vehicle containing a nuclear warhead. The purpose was to disable, destroy or disarm the arming mechanism of that warhead, due to an intense flux of neutrons generated by the Sprint warhead detonation.
Details about the design, purpose and politcal future of such a warhead ("the Neutron Bomb") are readily available in "The Truth About The Neutron Bomb', written by Sam Cohen -- the actual designer of the device.
ISBN 0-688-01646-4
Copyright 1983 by Sam  T. Cohen.