ALBUQUERQUE, N.M. — Sandia scientist Dr. Charles “Jack” Jakowatz has been selected to receive a 1996 Ernest O. Lawrence Award, one of the Department of Energy’s top prizes, for achievements that advance the use of synthetic aperture radar (SAR) to detect exceptionally small changes in landscape.
The technique is used to observe ground terrain from aircraft, through night and cloud cover, and can produced imagery with pixel size as small as one square foot.
The award — a gold medallion and $15,000 — will be presented to Jakowatz in Washington, D.C. in April. Six other winners will also be honored.
The work was funded by the DOE’s Office of Non-Proliferation and National Security.
Improvements in national security wrought by Jakowatz and his colleagues have made it possible for arms control and treaty verification personnel to patrol by air the borders of formerly warring states and announce definitively whether military equipment has been brought in or removed.
A second closely related technique has been used to produce very accurate terrain elevation maps. The technique could be used by a satellite-borne SAR to create a geologic map in approximately six months that would describe the varying height of the entire earth to a few meters. The same technology also has application to problems in geoscience, including the mapping of glacier motion and prediction of volcanic activity. The work also improves the accuracy of military strikes.
A third branch of the research produced a method for automatically focusing SAR imagery unavoidably blurred due to unpredictable motions of the carrier aircraft.
The award is named for the inventor of the cyclotron — an early particle accelerator. Lawrence directed one of the nation’s first nuclear laboratories during World War II at the University of California at Berkeley. Two major laboratories — at Berkeley and Livermore, Calif. — have been named after him.
“I am both honored and flattered to receive this award,” said Jakowatz. “But I would like to make it clear that a single person doesn’t make these contributions by himself. I see this as an award for my many Sandia colleagues who together have done a tremendous amount of good work.”
“His work is perhaps the most requested work by our VIP visitors and sponsors who come to visit. They request a presentation from Jack,” said Patricia Gingrich, deputy director of Sandia’s Systems Research Center. “His work is very effective in providing information on national security. We’re very proud of him.”
David Nokes, 5900 director who was vacationing in Mexico, voicemailed, “I am so thrilled for Jack.”
Said 5000 vice-president Roger Hagengruber, “It is a rare occasion when work not at the center of Sandia’s priority mission in nuclear weapons engineering receives attention like this. There are many people who have contributed, but no single person whose contributions have been more seminal than Charles Jakowatz. I believe this is one of the finest examples of technical work I have ever come across at any laboratory. I believe we should be proud not only of Jack but of the environment that made this possible at Sandia.”
How it works
The idea of using radar to image the ground has been around since the early 1950s, when the technique was used by pilots to produce generalized maps that showed coastlines and other large geographic features.
Radar works by sending out microwaves that bounce against objects. Those waves, captured in reflection by an antenna, can be used to construct images of what’s out there.
The problem was that an aircraft at great height could produce only a coarse image of ground features, because resolution was dependent on the antenna’s length. This arrangement, called SLAR (Side-Looking Airborne Radar) proved impractical because finer image definition depended upon lengthening the antenna to an unwieldy degree.
Synthetic aperture radar (SAR) advanced a different concept. SAR uses a short antennae, but transmits and receives many radar pulses as the airplane moves forward. This multitude of radar echoes are then integrated by signal processing techniques to synthesize an image of the same resolution as one that could be obtained by using an antenna as long as the flight path. This flight path is dubbed the “synthetic aperture.”
“The problem is that for the synthesis process to succeed, you have to know the position of the aircraft to a fraction of a wavelength — in this case, a fraction of a centimeter — each time it fires a pulse, and it fires on the order of 1,000 pulses a second,” said Jakowatz.
Although modern electronic navigation technology is good at determining aircraft position, the high resolution of modern SAR means blurring can occur from small unplanned movements of the plane — the result of varying air currents or other forces. One of the results of the Sandia research has provided a robust solution to this image resolution problem.
Improvements Added by Jakowatz Team
In three significant improvements, Jakowatz and his colleagues:
In 1989 patented a means to remove image blurring caused by the bouncing of the plane as it traveled through atmosphere. “We invented a technique that started with an out-of-focus image and could derive from that image the motion of the plane that was producing defocusing. Then the technique backed out that error and left behind the clear picture,” said Jakowatz.
In the early 90s, learned to process images of the same patch of earth taken in pairs, separated in time by days or weeks. “Using a procedure that detects changes in the images, we learned how to measure very subtle disturbances on the Earth’s surface. This can be of great value in arms control verification problems.”
In the mid-90s, learned to create a three-dimensional SAR product by comparing images taken in pairs from slightly different locations. Using signal processing techniques, these image pairs can be combined into an interference fringe pattern, just as an ocean wave penetrating a sea wall at two points form two sets of waves that alternately reinforce and quell each other. By analyzing aspects of the interference pattern, very precise terrain elevation information may be extracted.
“With this method, we can compute the elevation of the earth’s surface to a fraction of a foot,” said Jakowatz. In another model, the method can detect motion of the Earth’s surface in the time between two SAR collections. The ability opens the possibility of monitoring ground fault slippage to predict earthquakes, and monitoring the ground swell that normally precedes volcanic eruptions to warn of impending eruptions.
Flood plain management becomes simpler if you can map a river valley and knew accurately the elevation of the earth at any point, thereby knowing precisely where the water’s going to go. Even a one-foot change in elevation can be important in selecting the location of a dam.”
With SAR three-dimensional reconstructions, Sandia’s Advanced Manufacturing Center used stereo lithography to create a three-dimensional epoxy model of Washington, D.C. mall area. Data was obtained from the air at night when the city was under heavy cloud cover.
In l996, Jakowatz with colleagues Dan Wahl, Paul Eichel, Dennis Ghiglia and Paul Thompson, published a book, “Spotlight-Mode Synthetic Aperture Radar: a Signal Processing Approach.” The book, already in its second printing, was written “in the spirit of general scientific exchange, and as part of the mission of the DOE to share unclassified technology,” said Jakowatz, who said he was grateful to Sandia management “for fostering the kind of environment where this kind of research can be conducted.”
Jakowatz came by his interest in airborne microwave imagery from down-to-earth medical work on CAT scans at Purdue University as a graduate student. “I was fascinated that the same mathematical concepts employed to image the human brain using X-ray data taken from a series of positions surrounding the skull in computerized tomography could also be applied to a series of microwave bursts bouncing off the ground.”
Jakowatz did all his college work at Purdue in West Lafayette, Ind., receiving a bachelor’s degree in 1972, a Master’s degree in 1973, and a doctorate in 1976, all in electrical engineering.
Other recipients of the annual award, presented since 1960, have included some fabled names in science, including Richard Feynman, Louis Rosen and Sidney Drell. Only five Sandians have won previously: Pace VanDevender, Tom Picraux, Gordon Osbourn, Gus Simmons, and Tom Cook.
Sandia is a multiprogram DOE laboratory, operated by a subsidiary of Lockheed Martin Corp. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major research and development responsibilities in national security, energy, and environmental technologies and economic competitiveness.
Photo: Jakowatz holding a three-dimensional epoxy model of Washington, D.C. mall area.
Technical contact:
Jack Jakowatz, cvjokow@sandia.gov (505) 844-1704