An imaging infrared seeker that can improve the accuracy of the
JDAM satellite-guided munitions by more than 200 percent has been
tested successfully and is ready for production, said program officials.
The same technology also could be used in other types of bombs and
missiles.
The Joint Direct Attack Munition is a 1,000-pound or 2,000-pound
free-falling bomb with a strap-on Global Positioning System/Inertial
Navigation System (GPS/INS) guidance kit.
JDAM’s accuracy is nearly 43 feet in the GPS/INS mode and
100 feet with INS alone. The new seeker, using uncooled imaging
infrared focal plane array technology, would increase the accuracy
to about 10 feet. The system is called Damask, an acronym for direct
attack munition affordable seeker. Each system is expected to cost
$12,700, said Michael Dietchman, director of strike technology at
the Office of Naval Research. Each JDAM guided bomb costs about
$20,000.
Air-to-surface weapon accuracy is defined by circular error probable,
or CEP. That is the radius of a circle within which 50 percent of
the weapons will strike. The smaller the CEP, the greater the weapon’s
accuracy. The JDAM CEP is 13 meters. Dietchman said that the addition
of Damask to JDAM lowers the CEP to three meters (about 10 feet).
Three-meter accuracy is achievable with laser-guided bombs, which
can only be used in clear weather with direct line-of-sight to the
target, and require a dedicated designator. JDAM is less accurate
but often a preferred choice, because it’s satellite-guided,
so it works in bad weather.
The Office of Naval Research (ONR) developed and tested the Damask
seeker and has turned over the system to Navy weapon acquisition
officials. Damask could soon be used to upgrade JDAMs currently
in production at the Boeing Co.
“The acquisition part of the Navy is working with Boeing
to look at the design and where to go from here,” said Dietchman
in a briefing to the Precision Strike Association. “The science
and technology proved that it can work. Now it’s in the hands
of the acquisition community.”
The Navy and the Air Force collectively could buy anywhere between
20,000 and 100,000 JDAMs during the next several years. These weapons
were widely used in the 1999 air war over Kosovo and the campaign
over Afghanistan this fall. JDAMs are compatible with Air Force
B-2, B-52 and B-1 bombers, F-16C/D fighter aircraft, and with Navy
F/A-18C/D fighter aircraft.
On the question on whether Damask could be viewed as an alternative
to GPS, “one must be careful to distinguish between midcourse
guidance and terminal guidance,” said Gil Graff, program manager
for weapons science and technology at ONR. The Damask only is an
alternative for terminal guidance. Guidance accuracy, he said, is
limited by the capabilities of GPS and by the initial target location
error (TLE). An imaging seeker such as Damask can achieve “substantial
improvement in the final accuracy [compared to] inertially guided
weapons,” said Graff.
He said he expects that this technology will have applications
beyond JDAM. “While the initial focus of Damask was for JDAM
improvement, we believe that the technology will support much smaller
weapons—such as the Army Hellfire missile and the Air Force
Small Smart Bomb and [other weapons] as small as 2.75-inch rockets.
“The real power of an imaging weapon,” he said, “is
that it allows the munition size to be reduced substantially for
a given level of damage.”
In his briefing, Dietchman noted that, if the GPS signal were jammed,
Damask would be able to guide JDAM to the target nonetheless.
During tests last year, JDAM weapons, equipped with the Damask,
successfully hit targets when the GPS signal was jammed, he said.
The Damask has been in development for three years. In 1998, the
Raytheon Systems Co. received an $11 million Navy contract to work
on the uncooled focal plane array technology. The detector in Damask
is a thermal imaging IR camera produced by Raytheon for use in the
night-vision system of the 2000 Cadillac Deville.
The upgrade kit includes a seeker mounted on the nose of the JDAM
and processing electronics in the tail assembly.
Before a mission, an image of the target taken from infrared, visual,
synthetic aperture radar, satellite photograph or other source is
used to make a target template, which is loaded into Damask.
The target template can be created on a PC and loaded into Damask
before aircraft launch. A template also can be downloaded to the
aircraft from a reconnaissance unmanned aircraft or a satellite,
or can be generated from the launch aircraft’s onboard sensors
and loaded into the weapon during the mission.
For most of the mission, guidance is exclusively by GPS/INS. Then,
when the weapon is a few kilometers from the target, Damask can
be used to supplement GPS. It looks at the target for a second or
two and compares what it sees with the target template that’s
been loaded. If necessary, it updates the JDAM guidance unit.
A Damask prototype called GR-2 was tested a year ago at the Navy’s
air warfare range in China Lake, Calif. The test was designed to
duplicate a GPS-jamming scenario and measure the effect Damask would
have in improving the JDAM accuracy, Dietchman said.
The launch platform was an F-16 Fighting Falcon from Edwards Air
Force Base. Accompanying the shooter aircraft was a two-seat F-16
flying chase.
The pilot released the weapon at a slant range of about six miles,
altitude of 28,000 feet (mean sea level) and speed of 0.8 Mach.
From the point of launch, the JDAM received no GPS signals, navigating
solely on INS. The GR-2’s target was a square aluminum plate.
About 1,800 meters from the target, the Damask signal processor
compared the target-area view through the IR seeker with a target-area
template that had been loaded before flight, and then sent a correctional
signal to the JDAM’s tail-control surfaces, said Dietchman.
“Five seconds later, the weapon punched a hole in the target.”