MIT Reports to the President 1999–2000
Lincoln Laboratory is a mission-oriented laboratory operated by MIT for the Department of Defense (DoD) carrying out research and development in surveillance, identification, and communications. During the past year, agencies of the DoD–namely, the Air Force, the Army, the Navy, the Defense Advanced Research Projects Agency (DARPA), the Ballistic Missile Defense Office (BMDO), and the National Reconnaissance Office (NRO)–supplied approximately 89% 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 1999, Lincoln Laboratory received $350 million, supporting the efforts of 1200 professional technical staff.
The following administrative changes occurred at the Laboratory Steering Committee level. Mr. Lee O. Upton, Head of the Tactical Systems Technology Division, was promoted to Assistant Director on the retirement of Mr. Alan J. McLaughlin. Dr. Lewis A. Thurman was promoted to Head and Mr. Alan P. Bernard was promoted to Associate Head of the Tactical Systems Technology Division. Dr. Eric D. Evans was promoted to Head of the Ballistic Missile Technology Division. Dr. Roy S. Bondurant was promoted to Associate Head of the Communications and Information Technology Division, replacing Dr. Kristen Rauschenbach, who left the Laboratory to found a spin-off company. Mr. Frank D. Schimmoller, Chief Financial Officer, was promoted to Director of Administrative Operations.
Activity at the laboratory focuses on DoD tasks in surveillance, identification, and communications technologies, supported by advanced electronic technology 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; identification algorithms; 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.
The Bio-Aerosol Warning Sensor (BAWS), a UV-fluorescence-based detector of aerosols of biological origin, has been developed at Lincoln Laboratory to provide warning of a potential biological threat. The BAWS sensor is the result of a four-year development effort, and exploits the Laboratory’s previously developed microchip laser as a high-power, compact source of short pulses for exciting the fluorescent signatures of biological particles. Within the last year one dozen BAWS test units were integrated with the prototype Joint Biological Point Detection System (JBPDS) and demonstrated successfully in field tests at Dugway Proving Ground, Utah. Lincoln Laboratory is now transitioning the technology to industry for quantity production of the BAWS.
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-device focal planes with fast readout rates, combined with customized data processing systems, allow the LINEAR project to search an average of over 10,000 square degrees per month to a limiting visual magnitude of 19. During the period of March 1998 through June 2000, LINEAR searched 483,000 square degrees of sky and reported 2,172,640 observations, which were published by the Minor Planet Center at the Harvard-Smithsonian Astrophysical Observatory. The observations produced by LINEAR account for approximately 70% of the published observations generated worldwide during this period. This effort resulted in discovery designations for 419 new Near Earth Objects (NEOs)–a total of 1037 NEOs are now recorded by the Minor Planet Center–48 new comets, and over 68,000 main-belt asteroids. These discoveries account for over 70% of the worldwide discoveries of both NEOs and main-belt asteroids during this period. These results were obtained with a 1-meter telescope at the Lincoln Laboratory Experimental Test Site in Socorro, New Mexico.
Lincoln Laboratory is responsible for the design, development, and flight validation of the Advanced Land Imager (ALI) that will be launched on the National Aeronautics and Space Administration’s (NASA) Earth Observing-1 mission. 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. Fabrication, calibration, and environmental testing of ALI have been completed and the instrument has been mounted on the spacecraft. Integrated system tests are nearly complete and the launch on a Delta rocket is scheduled for November 2000.
Advances in sensor technology are driving emerging surveillance systems to incorporate spectrally rich sensors that cover larger areas. With this increase in data, there is an associated challenge to automate the data reduction process. Lincoln Laboratory has focused on automation techniques that enable both scene visualization and target detection. Scene visualization is accomplished by registering the multi-modality data to a three-dimensional site model and fusing the layers by using a model of the human visual system. Image mining techniques are applied to the fused data to automatically detect terrain features like roads, buildings, and trafficable areas. This information can then be used as contextual information for advanced target recognition algorithms.
An integrated visualization system to support the intelligence community was developed this year and is being deployed. This system provides an initial operational capability for visualizing color-fused three-dimensional scenes of areas of interest. Automatic search algorithms for detecting terrain features within these scenes can be trained by using a simple graphical user interface. This fundamental system is also being used by United States Special Operations Command to help enable night operations.
Lincoln Laboratory continues to support the Hyperspectral Technology Assessment Program that will lay out the frame work to characterize the potential value of hyperspectral imaging (HSI) systems to DoD operations, and will apply the framework to identify opportunities for near-term technology development and demonstration. The Laboratory approaches include defining assessment measures (e.g., performance, complexity and sensitivity measures), developing HSI taxonomies (e.g., applications, algorithms and sensors), performing empirical analysis, an, developing a performance model (an end-to-end statistical model consisting of sensor, processing and algorithm modules). Interactions with programs of the upcoming HSI space missions (NASA’s EO-1 Hyperion, Air Force’s Warfighter-1 and Navy’s Naval Earth Map Observer) has been an emphasis of the program as well. As space borne measurements become available during the next year, these data will provide further insights to operational HSI system capabilities.
The DoD has a program to develop and deploy a system to defend the United States against a limited ballistic missile attack. Lincoln Laboratory is supporting the NMD program at both the system and element levels. System work focuses on evaluating discrimination architectures against postulated and potential threats. Element support emphasizes characterization and assessment of early-warning radar, prototype ground-based radar, and exoatmospheric kill-vehicle seeker performance, primarily through design and analysis of flight tests.
The THAAD system is currently undergoing demonstration/validation flight testing at White Sands Missile Range, New Mexico. The system is designed to provide large-area defense against theater ballistic missiles. Lincoln Laboratory provides detailed characterization of the radar’s performance. In addition, the Laboratory conducts testing and analysis of the baseline decision algorithms, as well as continuous development and transfer of discrimination-algorithm upgrades for the THAAD radar. This year the Laboratory developed and deployed a data-analysis workstation to collect THAAD data and evaluate discrimination performance.
Over the past several years Lincoln Laboratory and the Advanced Electronic Guidance and Instrumentation System (AEGIS) program office have been developing a theater ballistic missile defense (TBMD) capability. This capability is separated into two programs: a Navy lower tier Area system and a Navy upper tier Theater-Wide (NTW) system. Both programs differ greatly from the current AEGIS anti-aircraft warfare capability. The challenges associated with detection, discrimination, and handover of hostile targets within a TBMD complex have been an area of active Laboratory work. The Laboratory has developed algorithms for synthetic wideband radar measurements and algorithms to improve infrared (IR) focal-plane performance, which includes the use of a two-color focal plane. These algorithms are particularly challenging for the NTW system performing discrimination in the exoatmosphere.
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. The ASTB is based in a Gulfstream II aircraft and provides high-fidelity radio frequency (RF) and IR reference instrumentation sensors that are used in parallel with special-purpose wing-pod payloads carrying production seekers or sensors under test. The combination of the system under test with the instrumentation sensors yields insight into the performance of sensor systems and advanced signal processing algorithms.
This year, ASTB activities include two major test campaigns and integration of new seekers. Two test campaigns have been conducted in Nevada to continue evaluating the effectiveness of electronic countermeasures against modern surface-to-air missile systems. One of the targets in these campaigns is the Airborne Countermeasures Test System, which is described below. One of the principal sensors in use was the RF seeker pod, first flown in 1997. A control architecture was implemented for the RF seeker pod so that its actions can be controlled by a ground-based radar, allowing flight testing of target intercepts in which the tracking radar and the seeker share data and act as an integrated system. Because the ASTB also carries IR focal-plane arrays and IR seekers, these and previous flight tests also provide data to evaluate the degrading effects of background clutter on the detection and tracking of target aircraft. Two new RF seekers with different designs have been received, and each is being integrated into a flight-test configuration, with completion expected at the end of 2000.
ACTS is a Falcon-20 business-class jet converted to operate either as a versatile target for testing of current and future air defense missile systems or as a global positioning system (GPS )jamming platform. The ACTS can provide a variety of electronic countermeasures (ECM) and can be configured to operate at L-band, X-band for Ka-band. Two X-band towed decoys and a terrain bounce antenna can provide repeater and noise outputs and other ECM techniques including range- and velocity-gate pull-off and false targets provided by a digital RF memory. Situational awareness is provided by real-time communications and GPS. The ACTS has been operating since 1997, and in the past year, campaigns were conducted for DARPA and the Air Force.
Most airborne radars deployed in operation today form only a few signal products from the antenna array focused on retrieving target amplitude, velocity, and elevation/azimuth. Backscatter from land clutter or interference from jammers, however, can quickly overwhelm such systems. The DARPA Mountaintop program had previously demonstrated that a versatile solution to this problem exists in the form of digital beamforming–element-level signals are directly digitized and combined to form customized target beams that are specially designed to adaptively suppress both clutter and jamming. This type of beamforming is referred to as Space-Time Adaptive Processing (STAP). Early this year an embedded STAP system for clutter and jammer suppression in an airborne early-warning radar demonstrated real-time performance of 185 billion computations per second. The embedding goal was achieved by combining custom standard-cell front-end very large scale integrated (VLSI) circuits filtering followed by a commercially produced massively parallel processor with nearly 1000 computing elements. Software for the processor features a layered parallel implementation, wherein the application code is isolated from the underlying machine architectural details.
The Lincoln Laboratory effort in support of a planned DARPA Discoverer II surveillance program was focused upon developing ground moving-target processing techniques for use with space-based radars. A laboratory prototype of a front-end processing approach for the demonstration system has been completed. Two custom bit-systolic array VLSI chips were used for each pair of receive channels to subdivide the 180-MHz data stream into 48 subbands, for a total of 54 billion operations per second. The down-sampled data, clocked at 10 MHz, is easily compatible either with onboard implementation of electronic counter-countermeasures (ECCM) and STAP or direct communication to the ground for subsequent processing.
Lincoln Laboratory has been selected as the system integrator for the Smart Sensor Web demonstration, a DoD multi-service, multi-national program. The program will develop a conceptual system design for a tactical information network for the lower-echelon warfighters. Products will include imagery to the warfighters from a variety of ground and airborne sensors; a sophisticated three-dimensional simulation capability for pre-mission planning; high-spatial-resolution weather forecasts; soldier physiological status; and a sophisticated profiled information delivery system. An operational test bed has been established at the Military Operations in Urban Terrain center at Ft. Benning, Georgia. A series of experiments have been planned to look at the functional components of such a system. Experiments begin in August 2000 and continue through April 2003.
Under the Next Generation Internet initiative, DARPA has sponsored a unique dark fiber communications research and application test bed called Bossnet. Bossnet extends four modern optical fibers from MIT and MIT Lincoln Laboratory to the Washington D.C. area near DARPA, enabling terabit-per-second communication. The test bed became operational in December of 1999 and is planned to continue operations for four years. New optical transmission methods are being explored to extend the bit-rate times distance product beyond the current state of the art, resulting in lower installation and operating costs. New applications including Gbps video and collaborative visualization are being developed, and advanced switching technologies will be added to the network for improved functions. Bossnet connects to the national DARPA-sponsored Supernet; this national connectivity among researchers will spark future technology developments and user applications to harness the tremendous power and capacity of fiber-optic communications.
The movement of military operations to precision strike and information dominance has resulted in large increases in communications data-rate and volume requirements, especially to small mobile or transportable satellite terminals. This year the Laboratory initiated a program to develop advanced modulation, coding, and multi-user access techniques that can increase efficiency of use of limited allocated bandwidth and transmitter power for future (>2010) satellite communications systems. Combinations of higher-order signal constellations and Turbo coding appear particularly promising.
Laboratory development of a test bed to demonstrate higher-data-rate waveforms for DOD’s next-generation protected satellite communication (satcom) system (Advanced EHF; 2004 launch) is nearing completion, with tests scheduled for September 2000. In addition, field demonstrations are being arranged with the Air Force of previously developed protocols for highly efficient transfer of bursty packetized data traffic over satellites. The Laboratory has developed interfaces to permit its satcom facilities to accommodate a heterogeneous mix of input/output devices in order to support the Services as they field the new medium-data-rate Milstar satcom system. The Laboratory continues to provide highly capable Milstar payload simulators for use by the Army at their user training sites.
There is an increasing awareness of the importance of information at all military echelons to ensure operational success. To provide this information, an integrated global communication system to provide connectivity between the sustaining base and the fighting forces is required. Satellite communications can provide the range and terrain independence required of the communication system, but the terminals must seamlessly integrate with both the military and public terrestrial communication system for data and voice transmission.
To provide this capability, Lincoln Laboratory completed this year a second 12-lb. Milstar satcom terminal and demonstrated operation at several Army bases. The terminal is novel in that it incorporates a web-server interface that is network addressable, supports multiple users, and implements router functionality. An encrypted voice-communication software application was developed as an example of the modern communication features that the new terminal design will provide the future Army. The program now is focused on a new antenna pointing system with a vehicle-motion-canceling design, and on developing algorithms to mitigate momentary blockage of the transmission path (by trees or buildings) to demonstrate a complete on-the-move satellite communications capability in a physical package that is easy to install on military vehicles.
Since the early 1990s Lincoln Laboratory has helped the Navy assess potential passive sonar signal processing improvements to compensate for the decreasing acoustic signatures from submarines. Several innovations adapted from Synthetic Aperture Array Radar techniques were shown to have promise. During the past several years many of these earlier ideas have been selected for transition to the operating fleet for evaluation. Two processing concepts for passive-array sonar are being transitioned to towed array systems in fleet operation: a full-spectrum normalizer algorithm that significantly improves operator displays has been tested at sea and an interactive passive acoustic classifier has been selected for testing in 2000.
The proposed entry of the submarine into support of warfare in the littorals raises the demand for high-rate communications with other assets in theater. In 2000, a comprehensive seatrial for a multi-element buoyant cable array demonstrated the benefit of spatial diversity. Adaptive combining was used to implement two-way communications with FLEETSAT at operationally significant data rates (>24 kilobits per second).
Lincoln Laboratory has a number of ongoing research programs focused on automatically extracting information from digitized conversational speech. Extractable information includes the language and transcription of the speech utterances and the identity of the speaker. Automatic speaker recognition is the process by which a speaker's identity can be extracted automatically from the speech signal. The Laboratory introduced the use of Gaussian Mixture Modeling and Universal Background Modeling as a means of solving the speaker recognition problem. The National Institute of Science and Technology (NIST) runs annual evaluations to measure state-of-the-art performance in automatic speaker recognition systems and to foster technology exchange in the area. Lincoln Laboratory has participated in each annual NIST evaluation, recently participating in the 2000 evaluation. Of the 11 international sites competing, Lincoln Laboratory systems produced the best performance in three of the four tasks in this year's evaluation. Ongoing research focusing on improving speaker recognition performance on voice that is transmitted by using Internet Protocols (voice-over IP).
Building on prior work in automatic language translation of text, Lincoln has initiated research efforts aimed at two-way interactive English/Korean speech translation; and automatic detection, extraction, and summarization of information from multilingual text sources, for an English-speaking analyst. During the past year, prototypes were developed of both systems. In addition, a summarization algorithm was developed, which automatically produces a brief summary of English language texts. Speech translation and translingual information processing were successfully demonstrated in June 2000, during a military exercise in Hawaii.
Lincoln Laboratory has previously developed a novel network-intrusion detection algorithm, called bottleneck verification (finds illegal user to root transitions), which has shown high performance in environments typical of large military bases. During the past year, this technology has been successfully adapted to operate in a wireless military tactical network environment. A modified version of bottleneck verification was developed for and integrated into host computers (called Appliques) on the Army Tactical Internet, and an additional intrusion detection algorithm, called persistent object monitoring, was also developed and combined with bottleneck verification on the hosts. In February 2000, this new integrated Lincoln Laboratory intrusion detection algorithm was tested during a Tactical Internet exercise at Fort Huachuca, New Mexico. Performance was excellent, with successful detection of 8 of 11 intrusion attacks and no false alarms.
Lincoln Laboratory is working with the FAA and NASA to enhance air safety, reduce controller workload, and increase airport capacity by developing planning aids for air traffic controllers. A FAA-sponsored effort is underway to develop algorithms that dynamically adapt air traffic control sectors to changing conditions, such as the passage of line storms. This activity will take advantage of new weather-forecast products developed in the Integrated Terminal Weather System (ITWS) program to adjust sector boundaries to minimize delay and avoid high-workload traffic concentrations.
Additional work sponsored by NASA Ames is being carried out to integrate advanced weather products developed by Lincoln Laboratory into the Center Terminal Automation System (CTAS) developed by NASA. CTAS helps coordinate activities between arrival controllers located at en route centers and final-approach controllers located at radar control facilities. The focus of initial work is on integrating wind field products from the ITWS in order to improve aircraft trajectory estimates. Concept exploration work is also underway on the use of ITWS convective weather products in CTAS for determining weather-impacted routes. NASA Ames is also sponsoring the Laboratory to develop the operational concept for the Surface Management System, a new automation tool to aid air traffic controllers with sequencing and separation of aircraft on the airport surface.
The FAA is sponsoring the Laboratory to perform flight test validation of Automatic Dependent Surveillance Broadcast in the United States and Europe. The technology, developed at the Laboratory, uses the Mode S secondary radar frequency and data formats to broadcast aircraft-derived position and state information. It enables air-to-air and air-to-ground exchange of more precise and timely information in support of more efficient air traffic management. The FAA is also sponsoring the Laboratory to assist with the development of time-difference multilateration, a technique for surveillance of the airport surface that will form the basis for improved management of surface traffic and the prevention of runway incursions.
The Laboratory-developed ITWS will provide comprehensive information on operationally significant weather at large airport terminals. Real-time warnings and forecasts of wind shear and other thunderstorm hazards enhance aviation safety. Traffic management functions are improved by using high-resolution information on winds along flight profiles and forecasts of precipitation impacts on flight routes. The Laboratory has provided extensive support in transitioning the ITWS algorithms to a production contractor and validating the implementation. Performance evaluations and site adaptation studies will be conducted as the initial production systems are deployed. The Laboratory continues to operate ITWS testbeds at Memphis, Tennessee, Orlando, Florida, Dallas-Ft. Worth, Texas and New York, New York.
A Weather Systems Processor (WSP) for the Airport Surveillance Radar (ASR-9) has been developed by the Laboratory and successfully transitioned to an industrial contractor for implementation at 35 airports nationally. This system employs innovative signal- and image-processing techniques to detect low-altitude wind shear and track thunderstorm movement by using existing terminal aircraft tracking radars. Ongoing work will support algorithm refinement and site adaptation as the WSP is deployed nationally in 2001 and 2002.
A Medium Intensity Airport Weather System (MIAWS) has been developed to provide real-time, high-resolution information on thunderstorm location and movement at small airports that will not receive a Terminal Doppler Weather Radar, ITWS or WSP. MIAWS utilizes data from the National Weather Service’s Doppler Weather Radars (WSR-88D or NEXRAD), together with Lincoln Laboratory—developed data-quality editing and storm-tracking software to address safety concerns raised by last summer’s fatal commercial aviation accident at Little Rock, Arkansas. A Laboratory-developed MIAWS prototype is being tested at Memphis, Tennessee and Jackson, Mississippi.
The Laboratory supports the FAA’s Aviation Weather Research program to develop improved mid-term (one to six hour) forecasts of convective weather, and ceiling and visibility changes at major airport terminals. These challenging forecast problems require appropriate sensor data processing, numerical weather modeling, and a variety of advanced weather forecasting technologies. Operational demonstrations are underway at five major U.S. airports.
A program is underway under NASA sponsorship to develop an Adaptive Vortex Spacing System. This will utilize meteorological data and forecasts, along with explicit detection of aircraft wakes to adjust aircraft separations on approach and arrival so as to exploit currently unused capacity when the vortices dissipate rapidly or blow quickly away from flight paths. Extensive measurements of wake vortices and boundary-layer weather conditions have been carried out at several airports to validate and extend models for wake-vortex behavior. The development of an operationally usable pulsed Doppler lidar for wake vortex and tracking is underway.
Lincoln Laboratory pioneered the development of photolithography with 193-nm wavelength lasers and its transition to the industrial semiconductor sector. This year the semiconductor industry announced first production of integrated circuits based on this technology for patterning transistor circuits at gate dimensions of 130 nm; with refinements this wavelength will support 100-nm dimensions. The Laboratory’s current development of 157-nm technology has now emerged as the strongest candidate for supporting mass production of microelectronic devices at 70-100 nm gate dimensions in the years 2004—2007. The key novel technological elements at this short wavelength are the development of appropriate photomasks and photoresists. Lincoln Laboratory has in the last year developed an optimized 157-nm photoresist with better lithographic performance than any other currently available photoresist. It has also demonstrated patterning at the smallest dimensions ever achieved with optical means: dense lines and spaces with 90-nm pitch using 157-nm interference lithography. The combination of these two achievements is a major step towards the development of a production-worthy 157-nm lithographic technology.
For the nearer term, functional transistors exploring the device limits of CMOS technology have been fabricated with 25-nm gate lengths by using phase-shift optical lithography in a industry-standard 248-nm exposure tool. This patterning at linewidths as small as 10% of the exposure wavelength, while it is a technique which is limited in its ability to print finely pitched structures without multiple exposures, is an effective means to create select isolated small gates, and thus can extend microelectronics by leveraging the large optical infrastructure existing at whatever wavelength is extant in the semiconductor industry.
The charge-coupled-device (CCD) detector arrays on the NASA Chandra X-ray observatory were developed at Lincoln Laboratory in collaboration with the MIT Center for Space Research. Since its launch in July 1999, Chandra has met expectations and supplied a wealth of new discoveries, including the detection of the most distant known object some 14 billion light years away. The CCDs have also provided richly detailed images with an angular resolution 100 times better than previous missions, enabling among other things the detection of a long-sought neutron star in the supernova remnant Cassiopeia-A. The CCD detector arrays have provided data for more than 60 scientific papers to date, and are expected to support research in the field over the planned 5-plus years of the Chandra mission.
David L. Briggs
MIT Reports to the President 1999–2000