Global Protection against Limited Strikes (GPALS)
In his State of the Union Address on 29 January 1991 President Bush stated: "Now, with remarkable technological advances like the Patriot missile, we can defend against ballistic missile attacks aimed at innocent civilians. Looking forward, I have directed that the SDI [Strategic Defense Initiative] program be refocused on providing protection from limited ballistic missile strikes, whatever their source. Let us pursue an SDI program that can deal with any future threat to the United States, to our forces overseas, and to our friends and allies."
The president's remarks provide the basis for the GPALS mission objective. This objective is to provide protection against accidental, unauthorized, or limited ballistic missile strikes by third world countries or the Commonwealth of Independent States directed against US power projection or forward deployed forces, US friends and allies, and the United States itself.
While the requirement for the US to deter a strategic nuclear attack remains, the evolving world situation also leads to a requirement for protection against limited strikes by ballistic missiles. BMD planning and any design of a GPALS system must take into account the possibility of unauthorized or accidental launches, whatever the cause or source.
The concern for accidental and unauthorized launch increases with the proliferation of ballistic missiles. Concern that loss of positive control over ballistic missile forces might occur in third world countries is real due to their lack of experience with weapon systems, nonexistent or inadequate weapon release procedures, absence of adequate physical and organizational safeguards, and the possibility of political instability.
The spread of missile technology of increasing sophistication and destructiveness is a trend that the US must consider as it develops military forces to be fielded in the 1990s. A prime example of this spread is the proliferation of ballistic missiles and weapons of mass destruction, including the capability to design, test, and fabricate chemical, biological, and nuclear weapons. One of the factors that mandated refocusing of the Strategic Defense Initiative program is the increased threat posed by the spread of ballistic missile capabilities around the world.
These technologies pose a threat today that is regional in character (e.g., shorter-range missile systems). However, the trend is clearly in the direction of systems of increasing range, lethality, and sophistication. The SDIO has assessed the proliferation of ballistic missiles and found that by the year 2000, some 24 nations will have a ballistic missile launch capability.
It is clear that some third world countries are striving to acquire or develop missiles capable of delivering payloads primarily at short and medium ranges, although a few countries could achieve intercontinental ranges through the conversion of space launch vehicles. This is a matter of concern in a world that may be increasingly affected by diverse geopolitical considerations.
According to the SDIO, the US cannot accept a situation in which these capabilities are allowed to constrain US national objectives, including US global and regional interests and responsibilities. Proliferation of ballistic missiles is a growing threat to the United States, its armed forces, and allied nations around the world.
Elements of Global Protection against Limited Strikes. GPALS would consist of surface- and space-based elements to ensure continuous global detection, tracking, and intercepting of ballistic missiles and their associated warheads, including theater missile threats. The defensive elements that would comprise GPALS could be deployed sequentially and need not await the deployment of an entire system. Nor would the deployment of a GPALS system be contingent on the technical maturity of potential follow-on systems.
A GPALS system would consist of surface- and space-based sensors capable of providing continuous, global surveillance and tracking from launch to intercept or impact of ballistic missiles of all ranges. The use of space-based sensors would allow for a reduction in the size, cost, and number of surface-based weapons and sensors, while increasing their performance. In combination, the sensors would provide information to US forces and potentially to those of allies as well.
A GPALS system would also contain interceptors, based both in space and on the surface, capable of providing high-confidence protection to areas under attack. Space-based interceptors could provide a continuous, global interdiction capability against missiles with ranges in excess of 600 kilometers. The surface-based interceptors (located in the US, deployed with US forces, and potentially deployed by US allies) would provide local point and area defense.
To illustrate the GPALS concept, figure 4 depicts an integrated system consisting of three interlocking pieces. The size of each piece reflects the relative investment projected for the three main parts of the GPALS. Specific elements are discussed under the section on GPALS architecture.
Common to all GPALS interceptors is the use of nonnuclear, hit-to-kill interceptor technology for destruction of all types of warheads--nuclear, chemical, biological, and conventional. These interceptors permit destruction of both the missile and the warheads well away from the targets being defended. The employment of multilayered defense will ensure multiple opportunities to engage hostile ballistic missiles, thereby providing a high level of defense effectiveness.
The theater/tactical element of GPALS will be able to be deployed globally by the United States. These forward elements of our ballistic missile defense will be transportable and could deploy with ground- or sea-based units. Friends or allies may also choose to deploy theater defenses that could be interoperable with those of the US. It is important to note that the space-based ballistic missile defense sensors will support theater as well as strategic defense operations.
The space-based Brilliant Pebbles (BP) element, after receiving weapon-release authority, would be an autonomous space-based kinetic energy interceptor. BP would provide global detection of an attack and means to destroy ballistic missiles with ranges greater than 600 kilometers. In the GPALS architecture, BP would operate against both strategic and theater ballistic missiles. Plans callled for about 1,000 BPs to support a GPALS architecture. The Global Protection against Limited Strikes architecture for ground-based defense against strategic ballistic missiles consisted of a command center and a combination of Brilliant Eyes satellites, terminal phase ground-based radar trackers (GBRT), and high-speed accurate interceptors. These interceptors would be terminal phase endo-exoatmospheric interceptors (E2I) and/or midcourse phase exoatmospheric ground-based interceptors (GBI). An option also exists to add the ground-based surveillance and tracking system (GSTS) to the architecture. BE satellites are derivatives of the previously planned space-based surveillance and tracking system satellites.
For planning purposes, the ground-based defense tier of a GPALS system includes the following:
1. approximately 750 ground-based interceptors,
2. six ground-based radars,
3. approximately 60 BE satellites, and
4. the appropriate command and control for the ground-based tier.
If E2Is are used, BE would provide postboost and midcourse surveillance and GBRTs would support terminal intercepts. The BE satellite would track the PBVs, clusters of RVs, and, in some cases, individual RVs to provide the data to commit the E2I. The GBRT would acquire, track, and discriminate between RVs and decoys in the late midcourse and terminal portions of their trajectories, providing kill assessment and additional target selections to the E2I. If GBIs are used, either BE, GSTS, or some combination of each will be used to provide cluster tracks for the GBIs.
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