John Call Cook
John Call Cook (April 7, 1918 – October 12, 2012) was an American geophysicist who played a crucial role in establishing the field of ground-penetrating radar and is generally regarded as contributing the fundamental research to develop the field. Cook is also known for demonstrating that aerial surveys can map surface radioactivity to enable much more efficient prospecting for uranium ore, for inventing electrostatic detection of hazardous ice crevasses, and for developing other novel techniques in remote sensing. During most of his professional career, Cook specialized in the techniques of remote sensing and the detection of underground  objects. Early years. John Call Cook was born on April 7, 1918 in Afton, Wyoming, to Carl and Ella Cook. Carl made his living as an attorney and farmer, and was himself the son of Phineas Wolcott Cook and number 4 wife, Johanna. During his teens, John constructed various devices including a spark-gap device, a batteryless crystal radio, a six-inch telescope, and an underwater 'diving helmet' constructed of a cookie can with plastic sheet bolted and gasketed for vision, powered by a garden hose and three tire pumps ganged together. University. Undergraduate. Cook initially studied at Brigham Young  University then enrolled with the University of Utah to study Physics. In the Spring of 1941 Cook began work as lab assistant at the university, and graduated that same year. The war years. As a physics major during the war, Cook was recruited to work at the Radiation Lab at MIT where he was assigned to work in the "Experimental Systems Group - 44" under Dr. James L. Lawson in the Roof Laboratory. This group worked on advanced problems of radar systems, such as signal discernibility, anti-jamming, short pulses, and receiver design. For some time afterward this group's experimental  systems led the field in performance—its members were continually breaking new ground and extending the range of radar's capabilities. They used an S-band (10 cm wavelength) and an X-band (3 cm) set, each with several kinds of display, and later received a K-band set (1 cm) which could resolve the structure of a nearby gasholder. These sets had around 300 vacuum tubes each, and 10 to 20 adjustment knobs each, and many interconnecting cables. Nearly every day a vacuum tube would fail, and they would have to trace and troubleshoot. They often tracked a B-17  bomber sent from Bedford Airfield for their use, trying variations in frequency and polarization, the use of chaff and jamming countermeasures, and trying to evaluate the use of propeller modulation signal amplitude to identify friendly versus hostile. M.I.T Rocket Research Society. Cook was elected president of the Rocket Research Society, a special-interest club, at the Radiation Lab. The American Rocket Society in New York had shut down for the duration of the war, but the M.I.T group continued development of liquid-fueled rockets. Cook built a portable test stand from a wooden box, with a thrust gauge, tanks for  fuel and oxidizer, valves with long control rods, and electric ignition. John, Bob Smith, and others built rocket motors of steel, aluminum, ceramic, silver from coins, etc., using the lathes and other facilities of the M.I.T Student Model Shop, where some of the members maintained the precarious good will of the man in charge. Some of their number managed to obtain liquid oxygen from the nearby Arthur D. Little company, which was developing a portable military "lox" generator and was dumping excess product fuming and freezing everything, into the gutter. The club hauled it to their test site in 5 -gallon steel cans insulated with fiber mat. This gave their most successful test—the rocket motor roared with a ten-foot plume of flame filled with standing shock waves, with the thrust gauge off-scale for ten seconds or more. But the aluminum motor burned out its throat and set the test stand on fire, which they put out with a Pyrene hand fire extinguisher. However the carbon tetrachloride produced phosgene and chlorine gasses (they deduced), which corroded all the metal. They still had gallons of liquid oxygen left, and so decided to make an explosion. The blast shot a  board 50 feet in the air end-over-end, and embedded gravel in the chest of the fuse-lighter, even with Cook's efforts at safety. This episode was exaggerated in MIT's humor magazine, where Cook was portrayed as the nonchalant "Lon Crook". In spring 1945 they received news of the German V-2 rocket-propelled ballistic missiles striking Britain. The German Rocket Society, with their government's support, had continued the work of American Robert Goddard and were far ahead of the U.S. However, their large, successful rockets had been applied at once to military purposes. Cook was disgusted  with this and so lost interest in rockets until NASA was formed. When it also developed that he would soon be leaving Cambridge, he resigned as president of the MIT Rocket Research Society and turned it over to Robert Kraichnan, who would later become prominent in relativity. Master of Science. In the Fall of 1945 Cook applied for and received a graduate assistantship at Penn State and began work on a master's degree. During his second year there he was appointed to teach Prof. Weber's junior year Thermal Laboratory course. Cook read extensively in the Physics Library on  gravitational topics, developed a thesis plan, and performed a program of experiments using an Eötvös torsion balance (an extremely sensitive gravity-sensing instrument) owned by the Geophysics Department in the Mineral Industries building. Prof. Sylvain Pirson there was pleased with the modifications Cook had made to improve the sensitivity of the balance, and with his administration of the course. However Prof. Duncan, the department head, advised Cook that as he'd had serious difficulty with some important mathematical physics courses, it was recommended that he leave with the MS and not come back. Graduated in 1947 at age 29. Somewhat  in shock from the experiences of his Master's, Cook drove home. He met L.V.S. Roos of Texaco, who headed a crew doing seismic prospecting for oil in the Utah area, and was hired on as Assistant Recorder at $300/month. Early each morning their crew of 8 would drive out with the recording truck, a drill-hole rig, and a water tanker to various sites marked by a survey crew. The drill crew made a 3" hole up to 150' deep and emplaced a dynamite charge. They laid out numerous cables 1,000' around the radius of the recorder  truck and attached geophones connected at intervals. Then a preliminary charge would be set off to 'spring' the hole, and then the main shot was made, requiring many switches to be thrown in a special order. This all required concentration and care as, once blown the hole could not be used anymore, and Cook was soon promoted for getting good data. Having a master's degree, Cook was treated as someone special by visiting Texaco officials and Mr. Roos, and it was suggested that he could be a Crew Chief or could be asked to join the laboratory staff in  Houston. These successes and being with family, had restored Cook's confidence. PhD. In late Fall, 1947 Cook received a telegram from Prof. Pirson at Penn State offering him a job in the Geophysics Department as a Research Assistant for $170/mo, to work on a PhD in Geophysics. Tuition would be only a nominal fee, and colder weather meant working on the field crew would be unpleasant, so Cook immediately accepted the opportunity. On arrival at Penn State he moved back into the Graduate Club and was accepted into the PhD program. Cook was made responsible for the  earthquake seismograph station so learned how to run it, read the records, and send reports to Washington. At Prof. Pirson's request he built their first vertical-component seismometer and arranged for visible-ink recording of its output upstairs in their offices, so they no longer had to develop photographic records to know when an earthquake was happening anywhere on Earth. In the Winter of 1949 Cook attempted to complete an experiment begun during his master's work: to detect a tangential gravitational field purportedly produced around a rotating body (according to certain published theories). He had not found it  with the small centrifuge in the Mineral Processing lab, so arranged to work with the massive turbine rotors at the Westinghouse Plant Apparatus Division, Atomic Power Plant Equipment, east of Pittsburgh, Pa. He drove to the plant several times with the Eötvös torsion balance in the back, and set it up close to one of the newly made rotors while it was being balanced at 3,600rpm on the giant factory floor. The balance needed to settle for an hour, and Cook needed one reading with the rotor stationary, then another with it turning at full speed; however random vibrations, the  starting and stopping for tuning, and heating and cooling to simulate operating conditions made stable readings difficult. Westinghouse engineers showed Cook blueprints of the building, which had a floor of great cast-iron plates 6" thick, resting on brick piers on bedrock. It could hardly be more sturdy, yet still vibrated from the machinery. Cook tried damping spurious modes by filling the delicate instrument with alcohol, but this induced more instabilities, possibly from thermal currents. During his final attempt at Westinghouse Cook was told that a famous engineer in the research lab wanted to see him, Joseph Slepian, who asked  about the theoretical basis of a tangential gravitational field, and proceeded to cast doubt as it's not an effect predicted by Einstein's General Relativity. Cook could not debate the matter and so gave up the pursuit. Also during that Winter and at Pirson's request, Cook built a model of an oil well with an electric logging system. This yielded data and curves which Prof. Pirson felt should be published, so Cook wrote "Laboratory Tests of Electrolog Resistivity Interpretation", which was published in The Producers Monthly. On the strength of that research Pirson nominated Cook for membership in  Sigma Xi, the national research honorary, in which Cook remained a lifelong member. Pirson then arranged for Cook to take over a research project for the Penn Grade Crude Association (a small group of oil firms in northwest Pennsylvania) with a salary of $300/mo and promotion to Research Associate. Another Research Associate, Bacon, and Cook were left with teaching all of the Geophysics courses; Bacon taught most, while Cook taught General Geochemistry for Fall-Winter, 1948-9 and worked in research. At the end of the school year, Pirson left the university for a better paying job with  an oil company in Tulsa, OK. All in the department were sorry to see this professor go. During the Winter-Spring of 1948-9 Cook did field work in the oilfields around Bradford in northwestern Pennsylvania as part of the Penn Grade research. These fields are famous for producing high-grade petroleum which is refined into Quaker State, Pennzoil and other superior brands. Cook saw the actual drilling and logging processes, although most wells were 30–50 years old with decrepit and rusty pumping equipment. A central engine running on natural gas (from the wells) in a shack, with steel rods  radiating out to wells all around (as much as 500' away), rocking back and forth on the ground or on stands. Here, Cook conceived an improvement in electric logging technique: a thin-sheet current path controlled by 'shielding-current' electrodes, analogous to the Kelvin potential shields he had learned about at the University of Utah. He built a model, which did indeed greatly improve the vertical resolution of the resistivity logging. Cook considered getting a patent, but soon learned that a similar system had been developed by another sole inventor and Schlumberger Well Surveying Corp, who were involved in patent  litigation with one another. Thesis. Prospecting for uranium had just become popular and, because the government had guaranteed to buy any uranium found, at an attractive price. Vast areas of the U.S. had never been explored for uranium, and a few lucky individuals became rich by finding ores with simply a geiger counter. Cook saw aerial prospecting as a new field of Geophysics, which needed analysis, so this became his thesis topic. How fast must the detector operate? How high and how fast could one fly? How small could a deposit of ore be and still be detected? How badly  would the geophysical anomaly be smeared and weakened by overburden and by the air? How serious is the interference from cosmic rays and background radioactivity? Cook was soon able to answer most of these questions with elaborate calculations based on library studies. However it was necessary to check and verify the calculations by model and full-scale experiments, insofar as this was possible. The Geophysics department had just bought a small, portable geiger counter, which did respond well to the gamma rays coming from rock samples Cook had gathered from the Mauch Chunk camotite outcrop. One could get crude quantitative  data by counting the audible "clicks" it produced over a minute's time. In this way, a gamma-ray "profile" of an ore stockpile at a uranium refinery at Rifle, Colorado was obtained during Cook's trip West in the summer of 1950. The ore was clearly detectable at a distance of a quarter-mile. However, it was known that equipment of much greater sensitivity would be needed for a practical airborne survey. In fact, scintillation detectors having both a much larger cross- section and much higher detection efficiency were already in airborne use in Canada and by the U.S.  Geological Survey, although many of the details were secret. Cook attempted to cast a large sodium iodide crystal in a glass baking dish, using one of the Department ovens, with poor results. (it's an art) With limited funds, he secured a large geiger-mueller tube 18 inches long, one inch in diameter, which was adequate for his thesis experiments. He developed the needed accessory circuits (high-voltage source and amplifiers, all battery-powered, a borrowed mechanical pulse counter, and 400 ft of lightweight, high-voltage twin cable on a portable reel). With this equipment Cook found the effect of  height on the gamma ray field from the soil (using flagpoles). He also ran fairly accurate (1.5%) radiation profiles at various heights over several gamma-ray sources: boxes of ore, the Mauch Chunk uranium deposit, and 0.1 gram of pure radium borrowed from a hospital! Heights up to 300 ft. were achieved using 6-foot hydrogen-filled balloons from the Meteorology department to lift the detector, preamplifier and cable. This work occupied much of the Winter and Spring of 1950–51. Cook wrote a careful thesis of over 100 pages, with 29 figures, which wife Vi typed in 3 copies, and  was approved by the committee. Cook continued teaching, including developing a new course in Oil Well Logging methods (electric resistivity, self-potential, gamma-ray, neutron, sonic velocity, etc.), which he taught to about 20 Geophysics seniors. He also tried to invent a gravity gradiometer for rock-density logging, however his first model using mercury and oil columns in glass tubes, showed the obvious fact that any ROTATION is equivalent to a gravity gradient, and a stabilized mounting is required. So Cook had to give up on this for an indefinite time. In 1951 Cook was the first PhD in Geophysics  to graduate from Penn State University. By this time he had produced three articles which challenged existing thinking of the time, ""Laboratory Tests of Electrolog Resistivity Interpretation"", ""Characteristics of Reservoir Models by Resistivity Logging"", and ""Can Gravity Be Abolished?"". His doctoral dissertation, ""An Analysis of Airborne Surveying for Surface Radioactivity"", was also published in the primary journal for the field, Geophysics. Professional life. Finding employment. His education nearly complete, Cook wrote letters offering his services to several oil companies and other labs (the natural employers of geophysicists) located in the subtropical Southwest, as wife Vi needed warmer climate. He received  five invitations to interviews in the Spring of 1951. In Tulsa at the Stanolind Oil Co. where Dr. Pirson worked, Cook got on well with Dr. Dan Silverman (Chief Geophysicist), but inexplicably never got a formal offer from them. In Dallas the Magnolia Petroleum Co. gave him a thorough day-long visit with several lab heads, and later made the largest offer of $525/month. In Houston, the Texaco lab did a superficial interview and offered $450/month. At the impressive Shell Oil Co. lab near Houston, the interviewer posed a question that required thorough familiarity with the  use of the binomial theorem, which Cook could not answer at that time (the interviewer was educated in Europe), so they made no offer. In San Antonio, Bill Mussen, head of Geophysics at the Southwest Research Institute (whose start-up literature Cook had seen at Penn State), showed a new organization and a fascinating project that needed him: evaluating new oil-finding inventions. They drove him to the hotel, and offered $500/month. Cook had reservations about working for Bill Mussen ("a dapper fellow, he seemed stuffy, on a different wavelength somehow") but accepted the job. Southwest Research Institute . Southwest Research Institute (SwRI) was founded by Tom Slick, one of the heirs of a millionaire oil wildcatter, on a big ranch west of San Antonio. Tom was an idealistic young man, hoping to provide a permanent asset to the region in return for what it had given to his father. He gave the land, with a few buildings, and about a million dollars for initial operations. SwRI was and is a non-profit organization like a university, but supports itself with research contracts from the government and industry. The Bulletin. Cook's initial assignment was to take over a  Bulletin service, titled ""New and Unorthodox Methods of Petroleum Exploration"". This service was supported by six oil companies who received the periodic Bulletins, considered confidential and proprietary. It had been expected initially that "new" oil-finding methods would be referred to the Bulletin for study by client oil companies, but this happened rarely or never. So Cook sought out the unconventional techniques by following up leads from research and ads in oil and gas trade journals. He arranged to meet with proponents to see their ideas and equipment in action, traveling the Western states, and attended geophysical and oil trade  conventions and exhibits. Cook became president of the San Antonio Geophysical Society for a year, and worked on the national convention of his main professional society, the Society of Exploration Geophysicists (SEG). Cook published several papers in the SEG journal, ""Geophysics"", which proved a very good way to publish his findings relating to exploration. Some local lawyers asked SwRI for a physicist to be an 'expert witness' on an auto accident case, and Cook was appointed. He was able to discredit an opposing 'expert' because he'd misread some trigonometric tables. Cook's lawyers won, and gave him $500  for this day in court. He was asked to help in other cases, but Bill Mussen objected to this, so Cook withdrew. To maintain his 'second profession' of teaching, Cook taught math in night school at the San Antonio College for two years, including trig, analytical geometry and calculus. The College wanted him to continue teaching there, but he felt it was at the cost of his research. In the three years Cook operated the Bulletin service he improved the composing and printing, and he'd done major analyses of several unconventional techniques, which appeared to have some scientific basis  or were being seriously considered by several oil companies. These included Surface Geochemistry, Gamma-ray Profiling, Radoil (profiles of the strength of radio waves), and Elfiex (which generated and measured sub-audio electric waves in the ground). In each of these cases, Cook not only observed field surveys by the proponents (in some cases for months), but studied all pertinent published theory and results, and sometimes did extensive model and field experiments of his own. The major conclusion Cook reached was that the ground is very difficult to 'see through' by any physical process provided by nature, and that the  conventional seismic reflection method was by far the best at that time. Cook found numerous variations of technique practiced by various proponents of radio-wave profiling; each man or group believed sincerely that his variation HAD produced anomalies or signals clearly correlated with deposits of oil. Such correlation was, to Cook, very hard to demonstrate. He found that in previous years, similar variations had been demonstrated in surface geochemistry and in radioactivity profiling, also with ambiguous results. He made a statistical study of the probability of finding oil, and included it in one Bulletin; it turned out that ANY method , even flipping a coin, will generally be right if it predicts "No Oil Here"... if you spend a fortune drilling, it will be a "dry hole". Then there were the practitioners of sympathetic magic, who naturally were attracted to petroleum prospecting by the hope of fantastic wealth. Most had no technical education and fell under immediate suspicion through their misuse of technical terms; some written claims were laughable. One man had attached a razor blade to a coat-hangar dowsing rod "to cut the lines of force". Some claimed to have special, secret powers. These Cook gave a full and  sympathetic hearing, and a careful performance test in the field; he found none who could perform as claimed. One gentleman, who styled himself "Doctor", had a crude diploma from a well-known mail-order diploma mill. Cook reported on them one and all, with his frank evaluation in the Bulletin, and sent each one a copy of his report on their method. This dissuaded no one; some continued to try to 'convert' him for years. After three years, Bill Mussen and Cook agreed that they had not found anything promising, nor were likely to, so ended the Bulletin service. Cook  published a full account in ""Geophysics"" and issued three bound volumes to clients, containing all the issues. As the Bulletin service was ending Mussen sold a contract to the U.S. Army Corps of Engineers (Fort Belvoir, Va.) to develop new methods of detecting buried, non-metallic land mines. Cook was in charge of this work for the next three years. It was classified Confidential, as a military job, and Cook's Secret clearance from the RadLab was again useful. Cook developed a theory and experiment for an electric-current technique with magnetic sensing, which gave trouble. He also developed a  thermal radiation method and did lengthy tests with a flake-thermistor detector, the best far-infrared detector then available. He and a SwRI electronics technician (Joe Wormser) tried acoustic/seismic methods, and evolved one technique that was fairly promising. They continued to improve instruments and techniques over the years, but could never defeat the many 'false anomalies' produced by variations of tilt and height of the detector, and by inhomogeneities naturally present in the ground. Eighteen years later their reports were declassified, and Cook published a research paper.