FAS | Space Policy | Star Wars | Programs |||| Index | Search |

Ground Based Interceptor [GBI]

The Ground Based Interceptor [GBI] is the weapon of the National Missile Defense (NMD) system. Its mission is to intercept incoming ballistic missile warheads outside the earthís atmosphere (exo-atmospheric) and destroy them by force of the impact. During flight, the GBI receives information from the NMD Battle Management, Command, Control, and Communications (BMC3) to update the location of the incoming ballistic missile, enabling the GBI onboard sensor systemto identify and home in on the target. The GBI would consist of a multi-stage solid propellant booster and an exoatmospheric kill vehicle. No nuclear weapons would be used as part of the NMD system.

The Ground Based Interceptor will have an acceleration profile and burnout velocity that maximize the interceptorís reach, consistent with the long-range capability of the supporting sensors. The GBI payload will be an Exo-Atmospheric Kill Vehicle (EKV) equipped with a high-sensitivity infrared seeker and an agile divert system to support endgame intercepts of responsive threats at very high closing velocities. In addition, the payload will be hardened to elevated doses of X-rays to allow operation in nuclear environments. To limit the adverse effects of this environment on the interceptor, the defense battle management will distribute the engagements within the available battlespace; the larger the battlespace, the wider the separation, and the weaker the deleterious effects of a nuclear environment. Also, to achieve high confidence of success against all threat objects, salvos of interceptors may be launched against each credible threat object. These salvos will be spaced in time to reduce the likelihood of correlated errors among the intercept attempts.

The initial GBI site deployment would be 20 interceptor missiles. The GBI seeker is expected to be able to do discrimination against initial simple threat countermeasure and penetration aid, though it would require assistance from ground-based radars or space-based sensors to address more complex and sophisticated targets.

The deployed GBI would be a dormant missile that would remain in the underground launch silo until launch. Launches would occur only in defense of the United States from a ballistic missile attack. There would be no flight testing of themissiles at the NMD deployment site. The technical status of each missile would be monitored and any required maintenance conducted at a contractorís offsite production facility. Interceptors in storage would be used to replace missiles requiring repair or selectively removed for reliability testing.

Each missile would contain approximately 12,595 kilograms (27,766 pounds) of solid propellant. The exoatmospheric kill vehicle would contain approximately 9 to 14 kilograms (20 to 30 pounds) of liquid propellant. These liquid propellants would consist of monomethylhydrazine and nitrogen tetroxide.

The GBI site would contain launch stations (silos), Interceptor Receiving and Processing Building, Interceptor Storage Facilities, and additional support facilities. Approximately 243 hectares (600 acres) would be required to support the GBI missile field and associated technical facilities. When the GBI site and associated technical facilities become fully operational, total site related employment would be approximately 150 to 200 personnel. Explosive Safety Quantity-Distance (ESQD) criteria would be used to establish safe distances from explosive hazard areas, such as solid propellants, to nonrelated facilities and roadways. These regulations are established by the Department of Defense. For the GBI silos, there would be a minimum 380-meter (1,250-foot) ESQD from inhabited buildings. In addition, the Interceptor Receiving and Processing Building and the Interceptor Storage Facilities would also have a 380-meter (1,250-foot) ESQD from inhabited buildings.

The interceptor, consisting of the solid propellant booster and exoatmospheric kill vehicle, would be shipped to the site in specially designed canisters using commercial carriers or government transportation. All shipping would be conducted in accordance with Department of Transportation regulations. Presently, there are no plans to store liquid propellants on-site. A small quantity of liquid propellants would be used by the exoatmospheric kill vehicle. The interceptor would arrive at the GBI site with the liquid propellants loaded and sealed inside the exoatmospheric kill vehicle. Additionally, the interceptor would be contained within a canister. Upon receipt, the canisterized interceptor would be monitored to inform workers if a leak had occurred during shipping. If a leak has occurred, a specially trained hazardous material response team and equipment would be used to remove any propellant from the canister. The propellant would then be contained and treated, as required. The Department of Defense and other government agencies have a long history of working with the solid and liquid propellants proposed for the GBI element and have developed standard operating procedures for the safe handling of these materials.

During normal daily operations, the only air and noise emissions would be associated with the electrical generators required to provide power to the site. These generators would only be required as backup power sources if commercial power to the site failed or if required to support a mission. At sites where no commercial power is available, or where the reliability of commercial power does not meet NMD system requirements, the generatorsw ould operate continuously.

To ensure an accidental launch of a GBI does not occur, the system would have a human in control at all times in addition to software and hardware safety systems. Additionally, stringent Department of Defense operating procedures, which prevent the launch by any one person, would be followed.

Development Activities

The Ground Based Interceptor [GBI], the national missile defense weapon element, consists of an exoatmospheric kill vehicle (EKV) launched by a fixed, land- based booster.

Three options are being examined for the GBI booster: the Minuteman III ICBM; a combinations of other existing solid- rocket systems; and an entirely new booster. Until booster development is complete, EKV flight tests will be flown on the Payload Launch Vehicle (PLV), which is a booster consisting of a Minuteman II second and third stage.

The EKV has a sensitive, long-range electro-optical infrared seeker which allows the EKV to acquire and track targets, and to discriminate between the intended target reentry vehicle and other objects, such as tank fragments or decoys. This enables the GBI to be launched against a cluster of objects and subsequently identify and intercept the targeted reentry vehicle. The EKV would also receive one or more in-flight target updates from other ground and space-based sensors, enhance the probability of intercepting the target. Based on this received data and its own sensors, the kill vehicle uses small on-board rockets to maneuvers so as to collide with the target, with both demolished in the high-speed collision.

GBI Element Description (113K)

Payload Launch Vehicle Ready for Launch (308K)

Payload Launch Vehicle Liftoff (205K)

Payload Launch Vehicle Successful Launch (416K)

Payload Launch Vehicle for Integrated Flight Test (53K)

IFT 1 Payload Launch Vehicle (PLV) Launch June 24,1997 (84K)

IFT 1 Launch
June 24,1997 (79K)


Sources and Resources

  • FY98 PEDS 0603871C National Missile Defense

    Ground Based Interceptor
    Ballistic Missile Defense Organization (BMDO) The Ground Based Interceptor (GBI) program takes advantage of prior interceptor technology and system investments. The exoatmospheric kinetic kill vehicle (EKV) portion of the interceptor destroys the attacking missile warhead by hitting it at high speed. The program's emphasis is to demonstrate early term intercept of high-speed, long-range ballistic missiles.

    Aerojet Tactical, Defense and Armaments. EKV Divert and Attitude Control Systems.

    FAS | Space Policy | Star Wars | Programs |||| Index | Search |

    Maintained by Webmaster

    Updated Saturday, August 05, 2000 3:13:04 PM