Despite the Bush administration’s bullish outlook on the
deployment of a missile-defense shield during the next decade, there
is a lot of work yet to be done in the laboratory, said U.S. government
scientists.
The United States could end up spending between $20 billion and
$100 billion to deploy ground-, air-, sea- and space-based anti-missile
weapons during the next two decades. The goal is to be able to intercept
and destroy in flight, both tactical and intercontinental ballistic
missiles that would be launched by potential enemies, such as Iraq,
Libya or North Korea.
But it would be foolish to deploy such anti-missile systems unless
they were intended to defeat not just the rogue-nation ICBM blitzes
that U.S. intelligence agencies predicted will occur in the decades
ahead, but also more advanced threats and sophisticated countermeasures
that may not have been conceived yet, these scientists said.
Among the most challenging technological problems confronting the
U.S. missile-defense program, they explained, is the development
of more capable sensors and interceptor weapons that can counter
multiple targets simultaneously, accurately discriminate between
warheads and decoys and put enough kinetic energy on the target
to destroy it.
The so-called “hit-to-kill” technology— based
on the notion that a warhead (nuclear, chemical or biological) can
be destroyed by smashing a high-speed projectile against it—has
been tested quite extensively in the past 30 years, said Darrell
Collier, chief scientist at the Army Space and Missile Defense Command.
During a question-and-answer session with reporters in Huntsville,
Ala., Collier acknowledged that mounting criticism about the lack
of emphasis on countermeasures has prompted U.S. program officials
and scientists to focus more attention on this issue. Countermeasures
are techniques—such as decoys, chaff and jamming—designed
to fool an interceptor. But Collier cautioned that those who accuse
the U.S. government of not doing enough work to address countermeasures
may not be informed enough, given that “countermeasures is
a very difficult subject to discuss in the open.” Much of
the technology related to countermeasures is classified, Collier
said.
Nevertheless, he said, “It’s beneficial to be reminded
that you’ve got to work this problem in a very uncertain environment—and
that the guys on the other side might well be thinking of these
things. ... With countermeasures, we have to make investments and
keep working. It’s not a closed universe.”
The idea that a kill vehicle is largely ineffective unless it can
discriminate between warheads and decoys has led to new requirements
in the missile-defense arena that had not been addressed in the
earlier years of the program, Collier said. In the 1960s and 1970s,
he said, scientists worried primarily about chaff and jamming. “Decoys
were not considered back then.”
In an attempt to address critics’ concerns, the Army and
the Ballistic Missile Defense Organization have created a program
called Hercules. Its purpose is to capture the data produced in
tests thus far, in the form of engineering simulations, sensor data
and algorithms that may help design more sophisticated weapons and
counter-countermeasures. “Hercules was a direct response to
those outside pressures [from critics],” said Collier.
Some of that pressure came from the Pentagon’s former director
of operational test and evaluation, Philip E. Coyle. In a 2000 report
he wrote before leaving the government, he noted: “Decoys
that provide a close representation of the RV [re-entry vehicle]
or modify the RV signature have only been minimally investigated”
by the U.S. missile defense program. U.S. officials, he added, also
have failed to study the use of “simple, unsophisticated countermeasures”
such as tumbling RVs and non-spherical balloons.”
He charged that the Pentagon oversimplified the flight tests by
removing decoys. The interceptors used in tests, Coyle said, had
been programmed with “detailed information about the target
suite—required to execute the discrimination algorithm—before
the flight test was performed.”
Among the most widely publicized criticism came from Massachusetts
Institute of Technology physicist Theodore A. Postol, who contended
that BMDO manipulated test data, in order to show that the kill
vehicle could discriminate between a warhead and a decoy.
According to Collier, the Army and BMDO scientists assigned to
the program are devoting more attention to the technologies involved
in discrimination.
“We have a large database of observations from both radar
and optical experiments that have been flown over 30 years,”
he said. There are, for example, about 1,200 radar observations
that could be used to improve current discrimination technologies.
The radar data— collected between 1962 and 1985 from various
systems—is managed at the Defense Department’s Lincoln
laboratory, located at Hanscom Air Force Base in Lexington, Mass.
The Massachusetts Institute of Technology manages the lab.
Optical data amassed between 1986 and 1996 was compiled under a
program called “optical discrimination and analysis,”
said Collier.
The Hercules program will combine the optical and radar data into
a repository that will be made available to scientists and program
managers. There will be “red,” “white” and
“blue” teams, each of whom will postulate target complexes,
formulate algorithms and “see whether the algorithms work,”
Collier said. “You can conceive of things we don’t have
radar data for. We can model any package that you want.”
The algorithms can come from “any source,” he said.
“There is a community of people in the classified arena who
are constantly thinking about algorithms and countermeasures. ...
One reasonable accusation about our community is that we were ignoring
the simple things that people could do (with countermeasures). So
it’s good to get some perspective.”
One potential advantage for the U.S. missile-defense program, said
Collier, is that it will be based on a multi-layered system. This
makes it difficult to develop countermeasures that can address all
layers at once, he added. Under the Bush administration plan, the
goal is to deploy weapons that can hit enemy missiles shortly after
launch (the boost phase), in the mid-course phase and the terminal
phase. Some of the weapons will work inside the atmosphere and others
in outer space. “It’s hard to do a countermeasure that
will handle both,” said Collier. “The enemy would like
to know which one he has to face. ... With layered systems, the
enemy doesn’t know if he is going to get hit in the boost
phase, the early ascent phase, or if he needs to provide countermeasures
to survive the re-entry” into the atmosphere.
A senior Navy official, meanwhile, downplayed the prospect of countermeasures
becoming an Achilles’ heel for U.S. missile defense systems.
Capt. Leonard Capello, assistant chief of naval operations for missile
defense, told reporters in Huntsville that the threat of countermeasures
often is exaggerated.
“We talk about decoys, we talk about countermeasures. But
there aren’t a whole lot of those out there right now,”
said Capello. “[But] we have to prepare for the eventual development
of countermeasures.”
The Navy is developing new technologies to improve its sea-based
missile-defense system, which only is designed to counter tactical
short-range threats. Capello said there are no plans to upgrade
the Navy system to defeat ICBMs, because that would be prohibited
by the 1972 Anti-Ballistic Missile Treaty. Such an upgrade also
would require the development of a brand-new missile, much larger
and faster than the current SM-3 (the Navy’s most advanced
Standard missile).
Among the technologies sought by the Navy is a two-color seeker
for the SM-3. A two-color seeker combines the information from two
different wavebands of the infrared spectrum to perform RV-decoy
discrimination.
The U.S. Navy also is working with Japan to develop a lighter nosecone
for the SM-3. There are plans to explore new X-band radar technology
in partnership with European allies, said Capello. X-band radar
is considered a prerequisite for any system that must perform RV-decoy
discrimination.
“We don’t have any agreements to co-develop any radar
with Europe or Japan, but we are discussing it,” he said.
The Army Space and Missile Defense Command also is proposing two-color
seekers as a technology that would help improve the accuracy of
missile interceptors. The ideal combination would be a two-color
seeker with a laser radar, said Jess Granone, the director of the
command’s technical center. Laser radar helps detect small
movements, he said, thus aiding in the discrimination of RV vs.
decoys.
To increase the likelihood that the real warheads, and not the
decoys, are destroyed, Granone advocates the development of “miniature
kill vehicles,” several of which could be packed on an interceptor.
The Army and BMDO are cooperating on this program, he said. The
technologies that must mature in order to make miniature kill vehicles
include micro-electro mechanical inertial sensors, compact lightweight
optics, miniaturized propulsion, energetic materials and focal plane
algorithms, Granone said.