Patriots Missed, But Criticisms Hit Home

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Science  16 Apr 1999:
Vol. 284, Issue 5413, pp. 418-419
DOI: 10.1126/science.284.5413.418

In the debate about ballistic missile defenses, the Patriot is Exhibit A—for both sides. “Patriot is proof positive that missile defense works,” said President George Bush during the 1991 Gulf War. At the time, Army assessments painted the antimissile system as all but perfect at intercepting Iraqi Scud missiles. But the Patriot received quite different reviews from two Massachusetts Institute of Technology (MIT) researchers who analyzed commercial video footage of intercept attempts. They said there was no evidence of a single successful intercept during the Gulf War (Science, 8 November 1991, p. 791).

Now a team of physicists and engineers has concluded that the video analysis was probably correct. The team was assembled by the American Physical Society's Panel on Public Affairs (POPA) and was led by Jeremiah Sullivan, a physicist and former director of the Program in Arms Control, Disarmament, and International Security at the University of Illinois, Urbana-Champaign. Accepted for publication at the journal Science & Global Security, the team's report analyzes all of the technical criticisms raised against the video evidence. It concludes that those criticisms are “without merit” and goes on to identify “an absolute contradiction” between the Army's scoring of Patriot performance and that video record.

Raytheon Co. the prime contractor for the Patriots used in the Gulf War, has already prepared a rebuttal, which is tentatively scheduled for a subsequent issue of the Princeton-based journal, according to its editor, Hal Feiveson. And the POPA study says nothing directly about the future prospects of the Patriot system, which has been redesigned entirely. But Theodore Postol, one of the MIT researchers, says that the Patriot affair may bode ill for plans to develop more expansive missile defenses to protect soldiers and the country as a whole (see main text). It reflects what he sees as a culture of exaggeration and cover-up that “has a corrupting effect on every aspect of weapons development.”

To one degree or another, everyone describes the Patriot as overmatched in its bid to destroy the Scuds. The Gulf War Patriot “was built to intercept airplanes, not missiles,” says Brigadier General Daniel L. Montgomery, the U.S. Army's Program Executive Officer, Air and Missile Defense. Traveling at speeds of up to 1.5 kilometers per second, the single-stage Patriot missile homed in on enemy aircraft using ground-based radar, then exploded near the aircraft. By the late 1980s, the system had been adapted to missile defense largely through software changes, and such refinements continued during the Gulf War. But the souped-up Scuds, called Al-Husseins, reentered the atmosphere at about 2.3 kilometers per second, and they often broke up, creating showers of confusing debris from which the warhead would emerge, corkscrewing to the ground.

“The Patriot had no chance, no chance against such a target,” says George Lewis, associate director of MIT's Security Studies Program. But U.S. officials initially claimed astonishing results. “The Patriot's success, of course, is known to everyone,” said General H. Norman Schwarzkopf on 30 January 1991. “It's 100%—so far, of 33 engaged, there have been 33 destroyed.”

That certainty soon began to crumble, even by official accounts. Under criticism by the U.S. General Accounting Office and other agencies that examined the Army data, the Army revised its success estimates from 96% in March 1991; to 69% in May 1991; to 59% in April 1992, when Representative John Conyers (D-MI) led a congressional inquiry into the Patriot's performance. Those final numbers, which include estimates of better than 70% success in Saudi Arabia and 40% in Israel, have not budged officially.

According to an analysis published in 1993 by Postol and Lewis and discussed at the Conyers inquiry, however, those numbers were not even close to reality. While the Army based its assessment mostly on inspecting ground damage after the war, Postol and Lewis found commercial videos (often from news organizations) of more than half of the approximately 44 Scuds engaged by Patriots. After taking into account unknowns such as viewing angle and distance and using fixed reference points such as the bright Patriot fireball to compensate for camera movement, the team found no evidence of even one successful intercept.


The redesigned Patriot-3 and the fireball from a successful intercept last month.


The video analysis, in turn, was repeatedly attacked as flawed by Robert Stein, now a Raytheon vice president, Peter Zimmerman, a physicist who was recently named science adviser to the U.S. Arms Control and Disarmament Agency, and others. Criticisms centered on the slow video-framing rates—which left 0.033-second gaps in the data—the difficulties of reconstructing three-dimensional events from the videos, and the possibility that Postol and Lewis had consistently misidentified the Scud warheads.

Now the six-member POPA panel has determined that Postol and Lewis correctly accounted for the limitations of the videos. Addressing a long list of criticisms, the panel found that Postol and Lewis had made proper assumptions about the physics and were not likely to have made major blunders like misidentifying warheads. “We don't claim that in every single case they have to be right,” says Sullivan. “But being wrong here or there doesn't change the overall physical consistency. It's not a matter of onesies and twosies.”

Stein and Zimmerman, who wrote the forthcoming “comment” on the POPA study, both declined to respond for this article. But Brigadier General Montgomery says, “Video footage showing less than full destruction of the Scud does not mean [it] was not deflected off its intended target.” Postol responds that there is no way to know just where the highly inaccurate Scuds were going in the first place, let alone whether anything deflected them.

The POPA panel has recommended that a third party undertake a joint study using the still-classified Army data and the videos. But with Raytheon turning up as the prime contractor for the “kill vehicle” of the proposed national missile defense, Postol warns that the Patriot episode raises more than technical questions. “Denial of failure leads to institutionalized failure,” he says. “And the message, loud and clear, was ‘We don't care about the truth.’”

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