MIT Reports to the President 1997-98
Lincoln Laboratory is operated by MIT as a Federally Funded Research and Development Center for performing research and development in advanced electronics. During the past year, agencies of the Department of Defense (DoD)--namely, the Air Force, the Army, the Navy, the Defense Advanced Research Projects Agency (DARPA), and the Ballistic Missile Defense Office (BMDO)--supplied approximately 84% of the Laboratory's budgetary support. The Federal Aviation Administration (FAA) provided most of the non-DoD support, which additionally includes work for the National Aeronautics and Space Administration (NASA) and the National Oceanographic and Atmospheric Agency (NOAA). Lincoln Laboratory also carries out pre-competitive research with industry under approved Cooperative Research and Development Agreements. For the federal fiscal year 1997, Lincoln Laboratory received $394 million, supporting the efforts of 1112 professional technical staff.
The following administrative changes occurred at the Laboratory Steering Committee level. Prof. Walter E. Morrow retired as the Laboratory's director on 1 July 1998, after having served Lincoln Laboratory for over 21 years. He is now Lincoln Laboratory's Director Emeritus. Dr. David L. Briggs became Director of the Laboratory and Dr. Herbert Kottler became Associate Director on 1 July 1998. Mr. Carl E. Nielsen, Jr., became Assistant Director for Administration. Mr. Lee O. Upton became Head of the Surveillance and Control Division, Dr. Kenneth D. Senne became the Head of the Air Defense Technology Division, and Dr. Lewis A. Thurman became Associate Head of the Air Defense Technology Division.
Activity at the Laboratory focuses on surveillance, identification, and communications technology development for the DoD, and on air traffic control technology for the FAA. Technical work areas include radar and optical sensors, measurements, and systems; communications; signal design and processing; lasers; solid state devices; digital technology, circuitry, and data systems; and tactical control systems. Unclassified summaries of several accomplishments during the past year are presented below.
Space-based radars offer advantages over airborne platforms for surface surveillance, including access to areas otherwise denied. Several radar satellites currently in operation provide synthetic-aperture radar imagery. However, satellite-based radar capability is desired to support tactical operations with rapid-response and near-continuous surveillance for both stationary and moving targets. The Laboratory is a key participant in the DARPA Discoverer II program. To meet the program's objectives, the Laboratory is developing a low-cost radar satellite for use in a low-earth orbit configuration of 24 to 48 satellites.
FOLIAGE-PENETRATION SYNTHETIC-APERTURE RADAR TECHNOLOGY
Lincoln Laboratory continues to support DARPA in its efforts to develop Foliage-Penetration (FOPEN) radar for detection of obscured ground targets. In August 1997, a major field experiment conducted by Lincoln Laboratory utilized the Naval Air Warfare Center ultrawideband UHF synthetic-aperture radar (SAR) and the Swedish National Defense Research Establishment CARABAS II VHF SAR to collect foliage-penetrating imagery. This experiment was performed at Fort Indiantown Gap, PA, collecting over 250 km2 of clutter data and over 250 views of targets in realistic deployments. Complementary data was collected with other sensors, including Lincoln Laboratory's X-band SAR. Data from this experiment is being used to support phenomenological studies as well as development of algorithms for automated target detection and cueing.
LINCOLN NEAR-EARTH ASTEROID RESEARCH (LINEAR) PROJECT
The LINEAR project operates a wide-area asteroid search program employing an advanced electro-optic search system originally developed for the Air Force space-surveillance applications. Recent advances in large-format, highly sensitive charge-coupled devices (CCDs) with fast readout rates, combined with customized data processing systems, allow the LINEAR project to search in excess of 10,000 square degrees per month to a limiting visual magnitude exceeding the 19th magnitude. This coverage, combined with an effective moving-object detection algorithm, has allowed LINEAR to be very productive when searching for near-Earth objects (NEOs), comets, and main-belt asteroids. During the period of only three months, March through May 1998, LINEAR searched 34,086 square degrees of sky and reported 293,598 observations to the Minor Planet Center. During this three-month interval, the observations produced by LINEAR account for approximately 80% of the asteroid observations generated worldwide. This effort resulted in discovery designations for 35 new NEOs (a total of about 500 NEOs are now known), 4 new comets, and over 7134 main-belt asteroids. These results were obtained with a one-meter ground-based electro-optical deep-space surveillance (GEODSS)-type telescope at the Lincoln Laboratory Experimental Test Site near Socorro, NM.
COBRA GEMINI RADAR
Since the end of the Cold War and dissolution of the Soviet Union, the missile data collection effort has focused on the Theater Ballistic Missile (TBM) systems of rest-of-world (ROW) countries. A key and consistent recommendation of studies addressing ROW missile data collection is the need to provide a low-cost, air- and ground- transportable, mechanical scanning dish radar system. Lincoln Laboratory has developed the prototype of such a concept: the COBRA GEMINI radar system. It will be used to acquire data on ROW theater ballistic missile launches. COBRA GEMINI operates at both S- and X-band frequencies and has wideband imaging capability. The system is currently in test and evaluation at the Millstone Hill Field Site in Westford, MA. The radar will be integrated onto a ship platform early this fall and undergo ship-based testing for the remainder of the 1998 calendar year.
THEATER HIGH-ALTITUDE AREA DEFENSE PROGRAM
The Theater High-Altitude Area Defense (THAAD) system is currently undergoing demonstration/validation flight testing at White Sands Missile Range. The system is designed to provide large-area defense against theater ballistic missiles. Lincoln Laboratory provides the independent assessment for all THAAD flight tests of the radar performance to the government evaluators, and also detailed characterization of the sensor's performance to the radar product office. In addition, the Laboratory conducts testing and analysis of the baseline classifier, as well as continuous development and transfer of discrimination upgrades being implemented in the next-generation THAAD radar.
THEATER MISSILE DEFENSE CRITICAL MEASUREMENTS PROGRAM
The Theater Missile Defense (TMD) Critical Measurements Program (TCMP) employs a sequence of flight tests executed at Kwajalein Missile Range (KMR) to provide IR and radar measurements that address critical TMD system-level issues. Lincoln Laboratory supports TCMP in four task areas: (1) mission planning and integration, (2) payload development, (3) fly-away IR sensor development, and (4) data analysis. The planning for the next campaign (TCMP-3) has begun, including four theater ballistic missile flights for the FY99-00 time period.
NATIONAL MISSILE DEFENSE GROUND-BASED RADAR PROGRAM
The Ground-Based Radar (GBR) program is being developed as a surveillance and fire control sensor for the National Missile Defense (NMD) system. The GBR-Prototype (GBR-P) is undergoing calibration and checkout at the KMR, and will be used during the NMD system testing in FY99. Lincoln Laboratory has provided support in several key areas, leveraging off the THAAD Radar program experience. This support includes test planning for the GBR Radar Credible Target (RCT) test to be conducted in February 1999, and development of data reduction and analysis tools for use in radar characterization and sensor performance assessment in flight tests. The data reduction activity includes development of workstations to be implemented at the GBR-P site to provide on-site data reduction and analysis, near real-time imaging, and sensor performance monitoring. Development and testing of algorithms to be implemented in upgrades for discrimination to the GBR-P software are continuing.
NAVY THEATER BALLISTIC MISSILE DEFENSE TECHNOLOGY PROGRAM
Over the past several years Lincoln Laboratory has supported the Advanced Electronic Guidance and Instrumentation System (AEGIS) office development of a Theater Ballistic Missile Defense (TBMD) capability. This capability is separated into two programs; a Navy Area System (lower tier) and a Navy Theater-Wide (NTW) system (upper tier), and differs significantly from the current Anti-Aircraft Warfare capability. Early work focused on both autonomous and cued search modes as well as predictive analysis based on the system's projected capabilities.
The Laboratory effort has been central to the characterization and modeling of the TBM debris environment, based on recent data collections by the KMR radars, Cobra Judy, and the Airborne Surveillance Testbed. This RF and IR debris characterization has gained wide acceptance within the Navy TBMD community and is impacting the design and requirements for both the Area and NTW systems.
AIR DEFENSE TECHNOLOGY
AIRBORNE SEEKER TEST BED
The capabilities of modern air defense missile systems have been severely challenged by the advent of low-observable vehicles and modern electronic countermeasures. The Airborne Seeker Test Bed (ASTB) is an instrumentation platform developed by Lincoln Laboratory to investigate these challenges and identify appropriate seeker architectures and signal processing algorithms for dealing with them.
A RF seeker pod added to the test bed in 1997 has undergone extensive measurement testing in Nevada. Additional efforts over the last year have focused on implementing a control architecture for this RF seeker so that its actions in flight are controlled by a ground-based radar. This architecture allows flight testing of target intercepts in which the tracking radar and the seeker share data and act as an integrated system. In October of 1997 a new IR seeker pod containing two seekers was added to the sensor suite, and has been used in air-air target detection and clutter testing. Flight testing with these RF and IR seeker pods will continue through the next year, with a focus on RF countermeasures testing.
MINIATURIZED DIGITAL RADAR RECEIVER
The modern battlefield requires that airborne early-warning surveillance platforms, such as the E-2C, detect small targets in the presence of severe jamming and sea/land clutter. Adaptive signal processing techniques, such as Space-Time Adaptive Processing (STAP), enable enhanced target detection capability in the presence of clutter and jamming. These techniques use multiple receive antenna channels and digital signal processing algorithms to shape the receive beam pattern in the spatial and Doppler domains. The current E-2C APS-145 radar has two receive channels; a significantly higher number of receive channels are required for STAP processing. A miniaturized digital receiver technology will significantly reduce the receiver form factor by using advanced multichip module technologies and by using one stage of RF down-conversion instead of the two or three stages used in conventional receivers.
Another challenge with STAP processing is that it requires a very high computational throughput. Each receive channel requires digital in-phase/quadrature down-conversion, channel equalization, and pulse compression prior to STAP processing. The computational throughput requirement could be as high as 2 to 10 trillion operations per second, which is too high for conventional parallel processors. Therefore, these front-end signal processing functions have been incorporated into the miniaturized digital receiver using a high-performance VLSI signal processor. A full custom CMOS VLSI signal processor was developed by using a very high-performance scalable bit-level systolic cell library. Each chip functions as a massively parallel signal processor and consists of tens of thousands of one-bit processors. Using massively parallel signal processing, each chip can perform up to 23 billion operations per second with an established 0.6-micron CMOS fabrication process. The resulting multichip module- based receiver/processor is approximately 3.5" x 5.0" x 0.5" and performs approximately 60 billion operations per second. The multichannel chassis being developed will contain 32 receiver channels, which will perform approximately 2 trillion operations per second in a cubic foot.
In February 1998, the Office of Naval Research (ONR) assumed sponsorship for the Radar Surveillance Technology Experimental Radar (RSTER) system at the Pacific Missile Range Facility (PMRF). The RSTER was relocated at the PMRF from April to June and became ONR's multisensor testing and integration site. The first major system to be integrated with RSTER will be a new antenna for the Navy's future airborne surveillance radar, the UHF Electronically Scanning Antenna (UESA). The UESA is a multi-element, cylindrically configured antenna currently being industry-developed and fabricated. The UESA is scheduled to be delivered to PMRF during FY99 for functionality demonstrations.
COMMUNICATIONS AND INFORMATION TECHNOLOGY
ALL-OPTICAL FIBER NETWORKS
Under the Next-Generation Internet (NGI) initiative, DARPA initiated a consortium to explore the application of Wavelength Division Multiplex (WDM) All-Optical Networks technology to access networks. In addition to MIT, the consortium includes service providers, router equipment manufacturers, and a WDM component manufacturer. Though Internet usage has soared, the low bandwidth and relatively high cost of the access network have severely limited the speed, applications, and overall accessibility of internet communications. The huge capacity and configurability of optical networks can be harnessed to improve this situation. The NGI access network initiative will explore physical-layer architectures that make the most efficient use of the optical technologies, and higher-layer software and protocols that work effectively with the underlying optical layer. A test bed will be constructed in Eastern Massachusetts to demonstrate and validate the architecture, technology, and software, as well as applications being developed under the NGI program.
During this year, concepts for extending networks over military communications satellites were implemented and tested in the laboratory. This work included the initial implementation of a teleport capability that interfaces remote military users of the Milstar communications satellite system to the public switched telephone network. This extended network will be used for secure voice and video teleconferencing, as well as to packet data services (such as the Internet and similar classified networks). Access control and traffic security issues continue to be under development.
Many of the satellite communications concepts and technologies being developed are also applicable to augmentation of tactical communications via micro air vehicles used as switching and routing nodes in a data network serving terrestrial (commercial and military) users. Individuals with small, handheld radios will be able to link into the network through the airborne platforms. These platforms are interconnected by high-rate backbone circuits and then to entry points on the ground, where interconnection with terrestrial communications systems can be accomplished. Since the aircraft can be quickly flown into an area of operations, there is little logistic strain in establishing a communications capability on the ground. The network also covers large areas from a single high-flying aircraft and is thus able to link together widely dispersed military units. A detailed engineering study of this concept was completed this year under DARPA sponsorship.
ADVANCED DISTRIBUTED SIMULATION
Under the Advanced Distributed Simulation Program, funded principally by DARPA and the Defense Modeling and Simulation Office (DMSO), Lincoln Laboratory developed prototype Run-Time Infrastructure (RTI) software for linking a broad range of DoD models and simulations. The prototype RTI software was used for a major demonstration in October 1997 as part of DARPA's Synthetic Theater of War program, which is being developed for use by the U.S. Atlantic Command. The software successfully linked 450 computers at seven geographically separated sites, supporting over 30,000 simulation objects. About 150 gigabytes of data were logged over 48 hours of continuous operation, without network disruption or data loss. The techniques used in developing the RTI software are now being considered for broader use in other applications that require reliable real-time database operations over heterogeneous networks.
COMPUTER NETWORK INTRUSION DETECTION EVALUATION
Lincoln Laboratory is performing a rigorous, objective, and repeatable evaluation of computer network intrusion detection systems. Under joint DARPA and Air Force Research Laboratory sponsorship, a realistic simulation network has been developed that can run real computer network attacks and anomalous sessions mixed with normal network traffic. Although this network contains fewer than a dozen real computers, it is able to simulate thousands of users on hundreds of PCs and UNIX workstations. Both the false-alarm rate of intrusion detection systems under normal conditions and the probability of detection for existing and new attacks are being measured. Prior work at the Laboratory using this approach with a simpler network and more limited traffic types revealed serious weaknesses in existing intrusion detection approaches and led to development of two new algorithms that reduce false-alarm rates by as much as two orders of magnitude. Training data are currently being generated and distributed to DARPA contractors. Test data will be shipped during September 1998, and the evaluation completed in the fall of 1998.
AUTOMATED ENGLISH/KOREAN TRANSLATION
In order to enhance communications among multinational forces in a tactical theater, Lincoln Laboratory has been working on a computer-automated translation system to relay command information. The initial effort has concentrated on Korean/English text, within the context of typical military sentence structure. In June 1998, the Laboratory demonstrated the first computer-automated English-to-Korean translation of an operational Commander's briefing and speaker's notes at the Combined Forces Command Korea. In addition, the Laboratory has developed the first interlingua-based Korean-to-English translation system, including a unique capability to handle the wide range of word-order variations that are typical in Korean.
AIR TRAFFIC CONTROL
Lincoln Laboratory is helping the FAA and NASA enhance air safety, reduce controller workload, and increase airport capacity by developing planning aids for air traffic controllers. The Center/Terminal Automation System (CTAS) developed by NASA Ames Research Center helps coordinate activities between arrival controllers located at en route centers and final-approach controllers located at airport radar control facilities. Lincoln Laboratory developed the prototype software now in operational use at airports in Atlanta, Denver, Los Angeles, and Miami. The Laboratory also wrote the system-specification and computer/human interface-requirement documents for the CTAS system currently in operation at the Dallas/Ft. Worth airport.
The En Route Air Traffic Management Decision Support Tool (ERATMDST) is a new FAA system being designed to assist air traffic managers and controllers in en route airspace by providing integrated conflict probe and scheduling capabilities. Lincoln Laboratory is also leading the effort to develop an ERATMDST test bed that integrates prototype software and display concepts developed at NASA Ames, MITRE, Lincoln Laboratory, and EuroControl.
SURVEILLANCE RADAR IMPROVEMENTS
The beacon surveillance systems deployed with radars such as the ASR-9 suffer from reflections off buildings, boats, signs, and aircraft that can cause false targets on controllers' displays. Lincoln Laboratory has developed dynamic reflector algorithms and software to automatically identify the location and orientation of the reflection sources and place this information in the beacon processor data base. Reflector information is then used to edit beacon reports and greatly reduce the occurrence of false targets. Dynamic reflection software was tested in the ASR-9 backup beacon processor starting in 1993 and is now being fielded in the production cards. Similar software was developed for the Mode S system in 1997 and was tested at two sites in 1998. This dynamic reflector capability will be fielded in the next several years.
The Traffic Information Service that provides pilots with the location of nearby aircraft by uplinking surveillance information gathered by the Mode S radar has completed FAA acceptance testing and is being installed in the 118 Terminal Mode S radars located at airports across the United States. The Text Weather Service and Graphical Weather Service provide pilots with weather text and graphics uplinked via Mode S from ground-based weather sources, including weather radars. Both services are available to users in the greater Washington, DC, area through the Mode S radar located at the Washington-Dulles radar in an ongoing evaluation program sponsored by the FAA. A version of the Text Weather Service, derived from information provided by the Laboratory-developed and FAA-contractor-built Terminal Doppler Weather Radar (TDWR), is available to airline users via the airline-sponsored VHF data link known as the Aircraft Communications, Addressing and Reporting System. This weather reporting service, called Terminal Weather Information for Pilots (TWIP), provides wind -shear, microburst, and precipitation messages to aircrews departing or approaching airports served by the TDWRs. TWIP is now deployed as a software upgrade to the TDWR software at all 44 U.S. TDWR sites.
AVIATION WEATHER DETECTION AND PREDICTION
The Laboratory-developed Integrated Terminal Weather System (ITWS) will significantly extend the TDWR capability in the areas of hazardous airspace identification, winds to support automation systems, and the short-term forecasts of significant weather. The transition is under way for the Laboratory-developed algorithms to generate the ITWS products from FAA and National Weather Service's sensors and the numerical models to the FAA's ITWS full-scale development contractor. It is expected that production versions of ITWS will be installed at major airports starting in 2001. The Laboratory continued to operate ITWS test beds in Memphis, Orlando, and Dallas-Ft. Worth airports to increase the ITWS data base and test enhanced products such as the prediction of convective storm growth and decay. An additional experimental site in San Francisco supports the development of ceiling and visibility products. An experimental ITWS, funded by the Port Authority of New York and New Jersey, for the New York City airports will commence operations in 1998.
BIOLOGICAL AND ENVIRONMENTAL MONITORING
BIOAGENT IDENTIFICATION SENSOR
In a collaborative program between Lincoln Laboratory and the Department of Biology's Center for Cancer Research, a new type of sensor for identifying bioagents is being developed. The sensor concept involves using genetically engineered B cells, or white blood cells, for the bioagent identification. B cells have been genetically modified to express a bioluminescent protein called aequorin as well as specialized antibodies on their surface that are specific to individual bioagent simulants. When a bioagent simulant binds and crosslinks these surface antibodies, a signal-transduction cascade fires within the B cell that triggers the aequorin to emit photons at a wavelength of 469 nm. This signal-transduction cascade provides a strong biochemical amplification. In recent experiments, the observed photon output of engineered B cells was 56 times the bioluminescent background within 30 seconds after a bioagent simulant was introduced into the solution containing the B cells.
NEW LANDSAT SENSOR DESIGN AND FLIGHT PROGRAM
Lincoln Laboratory is responsible for the design, development, and demonstration of the Advanced Land Imager (ALI) that will be launched on the NASA's Earth Orbiter-1 mission in December 1999. ALI is a land-imaging instrument that will demonstrate advanced technology to meet NASA's Mission to Planet Earth science needs in the 21st century. The new technologies dramatically reduce the size, weight, and power of ALI versus the LANDSAT-7 Enhanced Thematic Mapper. The ALI multispectral images will be compared with 100 to 200 images from LANDSAT-7 to validate the new technologies. Fabrication of the telescope and focal plane have been completed, and ALI is in process of instrument assembly to be followed by calibration.
IMAGER FOR ADVANCED NIGHT VISION
Lincoln Laboratory has developed CCD imagers providing, for the first time with an all-solid-state imaging device, useful imaging under starlight conditions at standard television formats. The results achieved at television rates with the CCD imager at 1.9-mLux scene illuminance can be compared to commercial CCD camera systems at 1000-mLux scene illuminance. These substantial improvements will bring greatly improved capabilities to night-vision systems.
COMPACT 3-D LASER IMAGER
Compact components are under development for a 3-D active imaging system in which the vertical and horizontal dimensions are augmented with the range dimension as obtained by timing the return of photons from a brief laser illumination pulse. The light source is a miniature diode-pumped, passively Q-switched Nd:YAG laser. The detection electronics combine a 2-D array of silicon avalanche photodiodes (APD) with an array of CMOS timing circuits, providing accurate timing within each pixel. Operating in a Geiger mode, each pixel can resolve the return of a single photon to sub-nanosecond accuracy.
HIGH-BRIGHTNESS 2-um DIODE LASERS
Efficient and compact high-brightness diode lasers operating near 2-um wavelength are of interest for such diverse applications as medical surgery and countermeasures against missile seekers. Lincoln Laboratory has developed high-performance 2-um diode lasers by using its molecular-beam epitaxy capabilities in the growth of various AlGaAsSb and GaInAsSb alloy layers. Diode lasers made in a tapered cavity configuration have outputs approaching a watt with near diffraction-limited beam quality. The tapered laser consists of a mode-filtering waveguide region and a tapered gain region combined with cavity spoiling grooves so that it can operate at high power without the destabilizing effects present in the more common rectangular-cavity lasers.
With CW output power in excess of 0.6 W with a horizontal divergence of only 0.7 degrees, the diffraction limit of the 140-um diode-laser output aperture has recently been achieved. Because the output of these lasers is highly divergent in the vertical plane and highly astigmatic (different focus in the vertical and horizontal planes), anamorphic optics are required to collimate the radiation.
In a complementary microlens technology at Lincoln Laboratory, a surface atom transport process is being used with GaP wafers to convert etched mesa structures into well-defined optical surfaces. Arrays of high-quality f/0.5 microlenses have been made, and output beams from these arrays of tapered lasers have been efficiently collimated by matching arrays of GaP microlenses, enabling multiwatt powers at high brightness levels.
LOW-POWER DIGITAL CIRCUITS FOR SPACECRAFT
NASA's New Millennium Program is launching a series of low-cost spacecraft for which an important mission is the demonstration of space capability for new technologies. The first of these spacecraft, Deep Space 1, will carry ultralow-power silicon chips fabricated in the Laboratory's Microelectronics Laboratory by using the 0.25-um fully depleted silicon on insulator (FDSOI) process.
The FDSOI chips comprise transistors and small circuits that will be tested periodically as the spacecraft moves through the radiation belts and away from the earth. The Laboratory-designed test board will automatically apply a sequence of test conditions. These results are to be reported to the central spacecraft computer and recorded for later transmission to the ground and analysis by the Laboratory. The board was integrated into the spacecraft in December 1997, with launch scheduled for October 1998. The goal is to make this low-power, high-performance process available for future spacecraft applications. Organizations are now submitting for fabrication designs of additional circuits using the Laboratory's FDSOI process.
More information about Lincoln Laboratory can be found on the World Wide Web at the following URL: http://www.ll.mit.edu
David L. Briggs
MIT Reports to the President 1997-98