Easily Distinguishable Objects in Target Suite

For the first five intercept tests, the "target suite" was identical: one mock warhead (the target) and one large balloon decoy. In the sixth intercept test, IFT-8, two small balloon decoys were added to the suite. The mock warhead looks very different from each of the decoys to the missile defense sensors. In particular, the Pentagon has stated that the large balloon appears much brighter (i.e., it has a stronger infrared signature) to the kill vehicle than does the warhead. Similarly, the two small balloons are much dimmer than the warhead. In addition, the X-band radar should have little difficulty in distinguishing the different shapes and radar cross sections of the warhead (which is a cone) and decoys (which are spheres).

In contrast, a real attack should be expected to involve decoys that more closely resemble a warhead, or warheads whose appearance has been disguised and decoys that appear similar to the disguised warhead. The Missile Defense Agency apparently assumes that certain signatures will correspond to either a warhead or a decoy. In an August 9, 2001 briefing, Major General Willie B. Nance, then director of the national missile defense program, said the defense will "&use physics-based information about objects" and "will recognize that there are certain features that are associated with certain objects"

But in fact, there is no reason to assume that either the warhead or decoys will have certain unique characteristics that can be determined by the sensors.

This 2.2 meter balloon decoy is the size used in the first three intercept attempts; for later tests it was replaced by a slightly smaller 1.7 meter balloon. In either case, the balloon is at least three times brighter than the moch warhead. Photo: L'Garde

This is an inflatible balloon decoy designed to look like a typical nuclear warhead in space. As put by L'Garde, the company that designed it, it is a "credible exoatmospheric optical-radar replica of a Mark-12 Reentry Vehicle" developed for MIT/Lincoln Laboratory, a Pentagon contractor. Photos: L'Garde.

It is also possible to place the warhead inside a balloon. Thus, rather than trying to make the balloon look like a warhead, the warhead looks like any number of identical balloons.

For a detailed discussion of how an attacker could use "anti-simulation" to make a warhead appear like a decoy, see chapter 8 of Countermeasures: A Technical Evaluation of the Operational Effectiveness of the Planned US National Missile Defense System (PDF), Andrew Sessler, et al, (Cambridge, MA: Union of Concerned Scientists and MIT Security Studies Program) April 2000.