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Terminal Imaging Radar (TIR)

The Terminal Imaging Radar (TIR) program, initiated under SDIO, developed imaging and discrimination techniques, and the radar scheduler functions. These are some of the most complex functions a BMD radar system must perform. In addition, SDIO and BMDO have funded several radar component technologies used in our ground-based radar systems. These include advanced X-band Solid-State Transmit/Receive (T/R) modules and waveform generators, and the Lexington Discrimination System used by MIT/Lincoln Labs to validate real-time imaging and processing algorithms.

Terminal Imaging Radar (TIR) was a radar intended for missile defense use in the terminal phase by High Endo-atmospheric Interceptors [HEDI] that need high resolution and discrimination information. In February 1983 the Sentry Interceptor Program, closely tied to the MX deployment, was terminated. Work on the data processing system and radar continued. The radar system, later renamed the Terminal Imaging Radar, was a predecessor to the current X-band radar.

As planned in 1988, an Airborne Optical System [AOS] would track the RVs initially, after warning from the boostphase surveillance and tracking system (BSTS) and possible designation by SSTS (if available). The AOS would hand target track information off to the ground-based terminal imaging radar (TIR). The TIR would discriminate RVs from decoys both on shape (via doppler imaging) and on their lower deceleration (compared to decoys) upon entering the atmosphere. Interceptors would attack the RVs at altitudes between 12 and 45 km. As of 1988 it appeared that the radar may be ready for deployment in the 1990s.

The TIR experiment was to demonstrate a ground-based, phased-array, X-band radar that can (1) receive data from the AOA, (2) acquire and track targets, (3) discriminate between threatening and non-threatening objects, (4) provide Information to help interceptors find and destroy reentry vehicles, and (5) assess reentry vehicle damage. The objective of the experiment was to demonstrate the capability to correctly identify reentry vehicles in time for interceptors to destroy them before significant damage is done. Although the Army had been conducting ballistic missile defense research and development for years, most of this effort had focused on defending targets such as Minuteman silos which have been hardened to withstand nuclear blast. Defending soft targets such as industrial centers and people will mean intercepting the enemy warhead6 at much higher altitudes so that ground damage will be limited even if the warhead6 detonate. This means that the radar will have to discriminate between the threatening and non-threatening objects at the higher altitudes. The Army now believed that the X-band radar will provide the needed capability.

The TIR experiment contracts were awarded in June 1985 to Westinghouse Electric Corporation and the Raytheon Company for preliminary design work. In December 1985, the Army exercised options under the contracts for detailed design of the radar. As of 1986 plans were to select one of the two contractors in December 1986 to build the radar hardware and conduct the experiment at Kwajaleln Missile Range.

The X-band radar will have more power and wider processing bandwidth than previous ballistic missile defense radars. with the additional power and wider bandwidth, the radar can more precisely track and identify enemy warheads. The TIR would have been first US X-band ballistic missile defense radar. The ability to generate images of reentry vehicles from radar data has been demonstrated.

Correctly identifying threatening enemy warheads is essential for an effective terminal defense system. The TIR will have an extremely limited amount of time for discrimination. To achieve a real time operational capability, the TIR will require highly accurate methods for identifying and classifying enemy warheads, and very fast data processinq hardware that has a very large memory capacity.

The TIR experiment was restructured because the funding for fiscal year 1986 was reduced from about $49 million to about $29 million. To stay within the reduced budget and to avoid slipping the experiment schedule, some performance requirements eliminated from the experiment. However, the officials said that the performance requirements eliminated from the experiment will have to be developed during a future development phase. Therefore, reducing the technical performance requirements during the experiment could increase the technical risk of any future engineering development. The estimated cost of the TIR experiment was $590 million.

The TIR experiment was restructured because the Strategic Defense Initiative Organization reduced the Army's funding for fiscal year 1986. The Army requested about $49 million for fiscal year 1986 but received about $29 million. According to officials of the Strategic Defense Initiative Organization, funding for TIR as well as other planned efforts were reduced to implement the lump-sum reduction by the Congress to SDIO's budget request for 1986. SD10 selected the programs to be reduced and the amount of the reductions.

The Strategic Defense Initiative Organization directed the Army not to slip the TIR schedule because such a slip would impact the planned early 1990s decision on whether to develop and deploy a ballistic missile defense system. To stay within the reduced budget and avoid slipping the experiment schedule, the Army reduced the planned work for the detailed design phase. The Army had originally planned to provide about $24 million to each contractor for the detailed design of each radar. However, because of the reduced funding, it provided $12 million to each contractor. As a result, the scope of work during the detailed design phase had to be reduced. A number of other reports were also eliminated.

The Terminal Imaging Radar was the predecessor to Ground-Based Radar Terminal (GBRT). In 1987 the GBR concept supplanted the proposed Terminal Imaging Radar (TIR) system in SDIO planning. The latter would have had a much shorter range (thereby not being useful for cueing the ERIS interceptor) and much less resistance to anti-radar countermeasures, such as jamming. The range of planned ground-based radars such as the Terminal Imaging Radar (TIR), which could discriminate RVS from decoys, might be too short to aid ERIS long-range interceptors; the TIR was planned for the lower HEDI endoatmospheric system. A longer-range Ground-based Radar (GBR) system was proposed that would be capable of supporting ERIS interceptors.

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