Space and missile defense

Joint Force Quarterly, Winter, 2002 by Donald R. Baucom

Since the dawn of the space age, developing space-based systems has never been a purely technological matter. The first orbital satellites raised questions on the legality of overflights and activities in space. The world community turned by habit to treaty negotiations and international law to resolve the implications of such issues.

Overflights were assumed away as the United States and the Soviet Union launched scientific satellites to mark the International Geophysical Year in 1957. De facto rights on overflight were established in October of that year when Sputnik went into orbit. Soon Washington and Moscow opened talks on restricting space-based military operations, with the United Nations providing the venue for creating a legal framework on the international governance of space.

With American prodding, the United Nations organized a Committee on the Peaceful Uses of Outer Space in late 1958, which became a major forum for developing international principles. The work of this committee, together with diplomatic efforts by the major nuclear powers, produced a number of agreements on military activities in space.

In August 1963, the United States, Soviet Union, and United Kingdom signed the Limited Test Ban Treaty in Moscow. This agreement, which eventually had over a hundred signatories, prohibited nuclear testing in space. Two months later, the United Nations adopted a resolution that banned nuclear weapons in space and in December 1963 passed a resolution establishing a set of general rules on the use of space. While this document included a requirement for "international consultations" before a nation took actions that might interfere with the peaceful use of space, it did not ban military systems. The terms of the resolution effectively allowed the United States and the Soviet Union to deploy military satellites. This result was not surprising: deployments had already become central to the space programs of the two superpowers.

The next major U.N. space-related agreement, the Outer Space Treaty of 1967, received unanimous approval from the General Assembly. Signed by 66 nations, it mustered a vote of 88-0 in the Senate. Its provisions did little more than consolidate the terms of the earlier resolutions and recast them in the form of a binding treaty. The superpowers remained free to deploy military satellites as long as they did not interfere with peaceful activities in space.

Space-Based Missiles

When the Senate ratified the Outer Space Treaty, the Pentagon had been pursuing missile defenses for two decades, starting with the discovery of German wartime plans for an intercontinental ballistic missile (ICBM) that could have reached New York by 1946. At the outset of the program, limitations in sensors, missile controls, and guidance systems required interceptors to be nuclear-tipped in order to destroy relatively small, high-speed targets presented by long-range missiles. The first American missile defense interceptor, the Nike-Zeus, was a large, ground-controlled projectile that carried a multimegaton warhead.

While the Nike-Zeus was in the initial stages of development, the Advanced Research Projects Agency (ARPA) was established as a response to the launch of Sputnik. Among its first efforts was Project Defender, the search for a defense against ballistic missiles. Previously, space-based missile defenses were considered impractical because of the on-orbit mass associated with a constellation of nuclear-tipped interceptors. However, when researchers gathered in 1960, that perception had begun to change. Their work indicated that it might become possible to develop an interceptor that could destroy targets by physically colliding with them. The energy released by such an impact would be six times that of exploding TNT equal to the mass of the interceptor. As one study indicated, this hit-to-kill (HTK) concept "removes the necessity of using a nuclear warhead and replaces it with a simple, cheap, lightweight mechanical device." That meant weight in orbit could be reduced by about two orders in magnitude. Boost-phase intercept was no longer mere fancy; it was a concept regarded as "sufficiently promising to warrant increased study."

Several of the concepts for space-based interceptors (SBIs) advanced in 1960 were capable of boost-phase kill and were collectively known as ballistic missile boost intercept (BAMBI). One of them was tire space patrol active defense (SPAD). It included a 30-ton satellite with an infrared scanner to pick up boosters, a computer to calculate their tracks, and 140 interceptors weighing 300 pounds each. Fired front the host satellite, each interceptor would deploy a wire web with a radius of 15 to 50 feet containing many 1-gram pellets fixed along the radial wires. Although the pellets could damage ICBM nose cones, causing them to burn tip on reentry, they were designed to attack vulnerable fuel tanks in the booster. Striking at velocities up to sixty thousand feet per second, they would inflict catastrophic damage. To ensure system effectiveness, 500 satellites would be orbited at air altitude of 250 miles above the earth.