U.S. ABM system still fail tests. No dome of protection from current ABM choices?
Another test of our antiballistic missile defense system this last June; it failed again. AviationWeek&SpaceTechnology, began its coverage with “another test failure casts doubt …” Yahoo News reported that the June’s launch was the 16th test of the new intercept hardware, of which 8 have worked. This is different from: the 8th successive kill of an incoming warhead in 16 tests.
This post is the first of several planned to review what has been done in American missile defense efforts. This is what we cover, this post —
- We start with an overview of why we try to do missile defense; basic ideas and terms used in this effort.
- Discuss discussion of the Safeguard system, our first (successful) attempt to provide ABM (Anti Ballistic Missile) interceptor protection.
Click any image to see its expanded form. Other posts discuss the current confusing situation, and why we are proceeding the way we are.
ABM issues form a shifting field of study
Attack missiles are usually divided into categories, as shown in this table. They describe the distance between the target and the launch point; but notice that the missiles range from relatively short range and slow to transcontinental and nearly orbital speeds.
A payload will range from high explosive (hundreds of equivalent TNT-kilograms) to thermonuclear (millions of equivalent TNT-tons), Fig 1. It makes sense to work to assure one does not drop in on us.
When is the best time to stop the attacking missile? During the rocket’s initial launch (boost phase)? Here it is a slow, compact target at its most vulnerable . Or, after the engines have been shut down and the payload is coasting through its trajectory (midcourse ballistic phase)? For long range missiles, this is the longest time the reentry vehicle is available to attack. Or, during the terminal phase, its reentry just seconds before it strikes? This is when it is moving fastest, but all aids
The table show the current categories for ABM techniques. MDA was recently changed from NMD, because mobile systems from the Army and Navy are becoming competitive to silo-based multi-staged rockets that the agency actually directs.
TBMD recently changed its T to stand for Terminal, because the military’s rockets all are meant to kill the attacking missile during re-entry, the final, terminal part of the ballistic trajectory.
The frequent shifting of words indicate an instability in ABM strategies. For example, when was the last time the categories battle tank and aircraft carrier were changed? The ABM situation will remain in flux until a functioning system has finally been devised.
MCTR controls how international rocket sales done. MCTR criteria indicate when ABM sales are legal, and were used against India some time ago.
Safeguard ABM Shield
We start with our historical ABM system. Safeguard was developed in the 1960s, tested in 1971, and installed to guard our North Dakota ICBM field in 1976. Safeguard was deactivated 4 months after dedication. There is a lot of political manipulation that we will not go into here, though Wikipedia has a nice description. In case of attack, Safeguard would have worked as designed.
In the 1950s, the successful Nike system (N-Ajax and N-Hercules) was developed to protect against bombers. Nike Hercules were distributed all around the world. In 2013, the last installations are being dismantled (60+ years later). The Nike Zeus was to do the same for missiles, but as it turned out, attack missiles are too complex for a simple Hercules-like solution. Fig 2, courtesy US Army, shows a Zeus-A launch at the Kwajalein testing island, early 1960s.
The kill task was split into parts, a midcourse interceptor to remove most of the warheads and a terminal phase interceptor to remove the reentry vehicles that slipped past.
The Zeus-A was not up to the designated job and quite a different -B model was designed.
The Spartan mission was a GMD for midcourse interception. It was to reach the vicinity of the warheads and detonate a 5 MT H-bomb.
No atmosphere, so no shock waves; the intense x-rays from the explosion would ‘cook’ the electronics and convert the incoming warhead(s) to duds. Destruction by x-rays – no contact necessary.
Catch the leakers. Sprint (Fig 4) was our original solution for the warheads that escape Spartan’s GMD net and enter the terminal reentry phase .
An H bomb was no solution to an intercept below several km where the interceptor had to operate. Such an “air burst” bomb most efficiently converts explosion energy into destructive shock waves.
So they used an enhanced neutron emission bomb, the original neutron bomb that caused such political concern in the 1960s and 1970s – very small nuclear explosion with ultra high yield of neutrons to destroy the bomb’s electronics.
The Challenge: Reentry starts at about 100 km up, where dense atmosphere starts, the decoys burn away, and the real warheads are revealed. Simplified arguments say that at this point we have less than 15 seconds to launch our interceptor and remove the now-known threats.
These 15 seconds are the challenge to effective TBMD.
The Solution: Sprint, Fig 5, was designed at the farthest part of the cutting edge engineering, sometimes called “bleeding edge technology.” It used primary explosive material as its fuel (secondaries like dynamite require an initiator to start) The advantage of a primary such as nitroglycerin is that it burns with much more rapidly. The disadvantage is that it occasionally decides for itself when to ignite.
Sprint was pushed from its silo by a piston, shown schematically in this Fig 6. The piston mechanically tilted the rocket toward the target. It ignited with 100 g acceleration and triggered its N bomb when it came within range of the warhead. End of incoming threat.
100 g – imagine a 200 lb (98 kg) man becoming 10 tons in an instant. Flesh would turn to paste, most metal objects would be crushed by their own weight
To an observer, Sprint sat quietly in its silo, there was an instant flash and it was as though it had disappeared.
If Sprint missed its target it had to self destruct a second or so after expected contact, or it delivered its neutron bomb into friendly territory.
Sprint was a complex of engineering issues. It moved so fast that its shell became incandescent and the air around it turned into a glowing plasma. The body had to be cone shape to survive the acceleration stresses. The design of guidance electronics to survive high g stresses and EMP from the plasma environment must have been challenging,
A Sprint prototype, called HiBEX, successfully accelerated at 400 g. Sprint accelerated at 100 g, its burn lasted longer and it was more agile. So the HiBEX operation diagram of Fig 5 is not quite right for the Sprint image.
Safeguard – Requiescat In Pace
The Safeguard system was designed, tested and finally proven over the 15 or so years ending in 1971. Only one ABM base was allowed by the treaty with the Soviet Union, with 30 Spartans and 16 Sprints. It opened in 1976, near Nekomo, North Dakota. In time of war, the missiles would have done their job as advertised. In the absence of an overwhelming saturation attack, almost certainly no warheads would have detonated on our ICBM missile silos. However, the base was closed 4 months later. There were many bad decisions in those days. This was not one of them.
Closing our ABM base was astonishingly clear minded. Although no enemy warheads might have gotten through, there would have been plenty of nuclear explosions; almost certainly no one in a 10 mile band about the ICBM field would have survived– it is possible that Safeguard defense might even have disabled ICBM launch, prohibiting revenge retaliation.
The Sprint missile suffered many mishaps. It had a reasonably good record for a missile but a bad one for a delivery system of neutron bombs. Nuclear weapons ought to be like family cars, with about 1 failure in 100,000 firings (if fewer, maybe your own side is destroyed).
Safeguard and Operation Argus Mishaps during the 0.2 seconds of launch promised disaster, but even with no launch issues, the 20 Sprints would detonate as low as 5000 ft ( nearly 1 km) above the surface in a last attempt to stop the incoming H-bombs. But, the Spartan midcourse missiles would have detonated thirty 5 MT bombs between 60 miles (100 km) and 350 miles (560 km).
Figs 7, 8: In August and September of 1958, Operation Argus fired three small 1.7 kT plutonium bombs above the South Atlantic at altitudes of 100, 182 and 466 miles (160, 290, and 750 km).
This shot generated electrons moving in magnetic field lines between Earth’s N and S poles. They disabled radar and radio and caused EMP current surges that burned out circuits in solid state boards. The man-made radiation belt was an actual dome, not of safety, but of destruction.
Safeguard would release 150 MT of energy and would send EMP shocks everywhere. Only the very most hardened sites would survive, certainly not civilian power, communication, or any other electronic equipment.
News of the top secret tests leaked out within a few months. By 1959 everyone understood what exo-atmospheric nuclear explosions could do, even just in testing. At this time the U.S. was covered in a copper wire and cable web that would have blown completely.
Military shifted to microwave communication but did not focus on the heightened susceptibility of microchips to the heavy EMP of a nearby nuclear burst.
American leadership ignored the lessons from Argus! We designed and built Safeguard in the 1960s. Even in the 21st century, our power grid is still copper webbed across the land. Our shift to cell phones puts communication into unshielded microcircuits with their extreme EMP sensitivity. We are actually more susceptible to nuclear strikes than in 1958.
Safeguard did anything but form a wonderful dome of safety. Its shutdown made us finally safe from our own “friendly” destruction.
Next in the ABM: Under The Dome series will be an analysis of modern choices.
Charles J. Armentrout, Ann Arbor
2013 July 22
Listed under Technology … Technology > Aerospace
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