from FAS - FederationOfAmericanScientists Website
Failing that, BMDO believes that
the creation of such a universal defense system would provide the
impetus for other nations to expand their security agreements with
the United States, bringing them under a U. S. sponsored missile
Energy for the sustained laser burst is
generated by the chemical reaction of the hydrogen fluoride (HF)
molecule. The HF molecules are created in an excited state from
which the subsequent optical energy is drawn by an optical resonator
surrounding the gain generator.
such systems continued through the 1980s, with the Airborne Laser
Laboratory, which completed the first test laser intercepts above
the earth. Initial work on laser based defense systems was overseen
by the Defense Advanced Research Projects Agency (DARPA), but
transferred to the newly created Strategic Defense Initiative
Organization (SDIO) in 1984. Work continues today under the auspices
of the BMDO, the successor to the SDIO.
The work on the Large Optics Demonstration Experiment (LODE), completed in 1987, provided the means to control the beams of large, high powered lasers. The Large Advanced Mirror Program (LAMP) designed and built a 4 meter diameter space designed mirror with the required optical figure and surface quality.
In 1991, the Alpha laser (2.8 mm) developed by the SDIO achieved megawatt power at the requisite operating level in a low pressure environment similar to space. Numerous Acquisition, Tracking, and Pointing/ Fire Control (ATP/ FC) experiments both completed and currently underway will provide the SBL platform with stable aimpoints.
Successes in the field of ATP include advances in
inertial reference, vibration isolation, and rapid retargeting/
precision pointing (R2P2). In 1995 the Space Pointing Integrated
Controls Experiment offered near weapons level results during
Designs for the SBLRD satellite call for four major subsystems:
The SBLRD is intended to demonstrate the capability to perform boost phase Theater Missile Defense from space.
The objectives of the
space demonstration include gaining performance information critical
to the development of an operational SBL system, as well as gain a
general understanding of operating such a system.
Because the design was intended for sea level operation, the MIRACL laser does not achieve the optimum efficiency necessary for space-based operation.
DARPA launched the Alpha laser program, with the goal of developing a megawatt level SBL that was scaleable to more powerful weapon levels and optimized for space operation.
In this design, stacked cylindrical rings of nozzles are used for reactant mixing. The gain generation assembly achieves higher power by simply stacking more rings. In 1991, the Alpha laser demonstrated megawatt class power levels similar to MIRACL, but in a low pressure, space operation environment.
Alpha demonstrates that multi-megawatt,
space-compatible lasers can be built and operated.
Tests verified that the surface optical figure and quality desired were achieved, and that the mirror was controlled to the required tolerances by adaptive optics adjustments.
This mirror consists of a 17 mm thick face-sheet bonded to fine figure actuators that are mounted on a graphite epoxy supported reaction structure.
To this day, this is the largest mirror completed for use in space. This LAMP segmented design is applicable to 10 m class mirrors, and the Large Optical Segment (LOS) program has since produced a mirror segment sized for an 11 m mirror.
The large dimension of this LOS mirror segment approximates
the diameter of the LAMP mirror
The current high power beam control technology is now being integrated with the Alpha laser and the LAMP mirror in a high power ground demonstration of the entire high energy laser weapon element.
is known as the Alpha-LAMP Integration (ALI) program.
In 1985, the Talon Gold brassboard operated sub-scale versions of all the elements needed in the operational ATP system including separate pointing and tracking apertures, an illuminator, an inertial reference gyro system, fire control mode logic, sensors and trackers. Talon Gold achieved performance levels equivalent to that needed for the SBL.
In 1991, the space-borne Relay Mirror Experiment (RME), relayed a low-power laser beam from a ground site to low-earth orbit and back down to a scoring target board at another location with greater pointing accuracy and beam stability than needed by SBL.
The technology to point and control the large space structures of the SBL was validated in 1993 by the Rapid Retargeting and Precision Pointing (R2P2) program that used a hardware test bed to develop and test the large and small angle spacecraft slewing control laws and algorithms.
The Space Pointing Integrated Controls Experiment (SPICE) demonstrated in 1995 near weapon scale disturbance isolation of 60-80 db and a pointing jitter reduction of 75:1.
In 1998, the Phillips-Laboratory-executed High Altitude Balloon Experiment, (HABE) will demonstrate autonomous end-to-end operation of the key ATP-Fire Control (FC) functions in a realistic timeline against actual thrusting ballistic missiles.
HABE will use a visible low-power marker beam as a surrogate to the megawatt HF beam and measure beam pointing accuracy, jitter and drift against a fixed aimpoint on the target.
Retargeting times are calculated at as low as 0.5 seconds for new targets requiring small angle changes. It is estimated that a constellation consisting of only 12 satellites can negate 94% of all missile threats in most theater threat scenarios.
Thus a system consisting of 20 satellites is expected by BMDO to provide nearly full threat negation.