81832_Ocean 8/28/03 7:16 PM Page 45 Special Issue—Scripps Centennial The Marine Physical Laboratory at Scripps Fred Spiess, William Kuperman Scripps Institution of Oceanography, University of California • San Diego, California USA 5912 LeMay Road, Rockville, MD 20851-2326, USA. Road, 5912 LeMay prohibited. Send all correspondence or Society is strictly to: [email protected], The Oceanography machine, reposting, or other means without prior authorization of portion photocopy of this articleof any by All rights reserved.Reproduction Society. The Oceanography 2003 by Copyright Society. The Oceanography journal 16, Number 4, a quarterly of Volume This articlein Oceanography, has been published As Scripps Institution of Oceanography (SIO) cele- been tapped and decided to support academic groups brates 100 years, its oldest research unit, the Marine in parallel with the maintenance of a much larger in- Physical Laboratory (MPL), turns 57, still carrying on house research establishment than that which had the tradition of leading innovation in seagoing, experi- existed before the war. Both the academic and Navy ment-oriented efforts to unravel the secrets of the communities were motivated by the probability that ocean and the subsea environment. The emphasis at the USSR would, as they did, initiate an energetic MPL in the early years was on ocean acoustics and geo- development of submarine capabilities built on tech- physics/geology. Though its research base has expand- nology and personnel drawn from Germany. ed to include physical and biological oceanography The key scientist at this point was Carl Eckart, an and atmospheric and ocean optics research, acoustics eminent theoretical physicist who had come from the and signal processing still play a central role as subjects University of Chicago to head the theoretical efforts of of research and as methods of ocean exploration and UCDWR (Figure 1). Eckart directed UCDWR during its imaging. Over more than a half century of existence, closing days, editing the laboratory’s final report, the emphasis at MPL is still on ocean observation and which ably summarized the newly gained knowledge exploratory research with the parallel development of while noting the underwater-acoustics challenges that unique technology to carry out this research. lay ahead (Eckart, 1946). Most of the UCDWR personnel and their programs The Early Years were taken over by the newly formed Navy Electronics MPL’s roots go back to 1941 when, faced with Laboratory, but Eckart foresaw the essential role that a large-scale destruction of ships by submarines in small parallel academic unit could play and was per- World War II, the nation mobilized the scientific com- sonally interested in many of the newly opening vistas. munity to learn how to defend against this threat. This view was shared by Roger Revelle, then still on Three university-operated laboratories were thus active duty as an officer in the sonar development com- established: Columbia University Division of War ponent of the Navy’s Bureau of Ships. The result was Research, Harvard Underwater Sound Laboratory, and an exchange of letters between the chief of the bureau1 University of California Division of War Research and the president of the University of California,2 (UCDWR). UCDWR was led initially by Vern Knudsen which led directly to the establishment of MPL in mid- of the University of California, Los Angeles, with sen- 1946 as a research unit of the university with a subse- ior staff recruited from academic institutions across the quent allocation of three tenured faculty billets. The country. Navy provided space and facilities in the Navy Given the primitive initial knowledge of the ocean, Electronics Laboratory on Point Loma, facing San and of the technology for dealing with its problems, Diego Bay. there was immediate progress as this new flood of Eckart had a multifaceted vision for the laboratory. activity built up. By the end of the war, there were He realized that studies of sound in the sea really effective new sonar systems and the beginnings of meant a study of the ocean environment and could thus understanding the environment, but there were also produce not only new sonar systems but also new new questions about the nature of the ocean and the understanding of the environment itself. This led to his seafloor and a vision of how to create even more effec- bringing Russell Raitt with him from UCDWR. Raitt tive detection systems. was a geophysicist interested in using acoustics to While many academics returned to their home uni- understand the nature of the earth’s crust as viewed versities at the close of the war, a few leaders had from an oceanic perspective. Eckart also had become become interested in the challenges and opportunities fascinated with immediate challenges that wartime they could see ahead. At the same time, some in the work had raised, focusing on two emerging problems. Navy realized the academic research potential that had One was the question of the anomalously high sound 1Letter from E.L. Cochrane, vice admiral of the U.S. Navy, to Robert Gordon Sproul, president, University of California, 31 January 1946. 2Letter from Robert Gordon Sproul, president, University of California, to E.L. Cochrane, vice admiral of the U.S. Navy, 8 February 1946. Oceanography • Vol. 16 • No. 3/2003 45 81832_Ocean 8/28/03 7:16 PM Page 46 Naval Missile Test Center. Spiess was appointed direc- tor in 1958. At that time, also, primary sponsorship of MPL was transferred from the Navy’s Bureau of Ships to the Office of Naval Research (ONR) and the sup- porting research equipment that had been provided by the Navy Electronics Laboratory was transferred to the university. MPL’s scientific and engineering staff grew during the 1950s, but primarily through strengthening the ini- tial threads. George Shor joined Raitt’s group and through successive expeditions they developed seismic refraction capabilities to map the structure of the crust beneath the deep ocean. The results generated a picture of the Pacific Basin that showed a crust much thinner Figure 1. Carl Eckart was the first director of MPL, than that of the continents and revealed the surprising which had grown out of the University of California fact that the quantity of sediment expected from millen- Division of War Research. nia of continental erosion was not there. This was one of the phenomena that forced the acceptance of the plate tectonics concept, explaining that as old crust was sub- ducted at plate boundaries, the accumulated sediment absorption that had been measured at sea in wartime was cycled onto and underneath the overriding plates. studies of sound transmission. This led him to recruit On the signal-processing front, theoretical con- Leonard Liebermann, a physicist who had been a cepts quickly outran hardware capabilities of the ana- member of the wartime effort at Woods Hole log world and vacuum-tube computers. At MPL there Oceanographic Institution, who was interested in were imaginative efforts to build new devices, particu- unraveling the interactions between sound waves and larly by Rudnick and Victor C. Anderson, a group molecular-level physical/chemical processes. Eckart’s leader who had been an MPL graduate student. other question was how best to detect signals in the Anderson was quick to see the opening provided by presence of noise. Within this context, his own work representing the sonar signal by a close-spaced series played a significant role in the birth of the field of of polarity samples, resulting in the beginnings of signal processing. digital-signal processing—a major advance that pro- Overarching these research threads were two vided the base for experimental sonar installations, guiding operating principles: to devise innovative soon put to use in Navy operational systems. The first experimental approaches to problems and to involve of these was the delay line time compressor (DELTIC; students in the resulting research. Eckart recruited Anderson, 1955), a system in which a simple digitized two more experimentalists—Phillip Rudnick and Fred version of an acoustic signal could be repetitively and Spiess—as well as a number of short-term visiting rapidly played back as the basis for making fine-scale physicists from other institutions. Graduate students correlation or frequency analyses over wide frequency were involved in the program from its inception in bands in real time. The second was digital multibeam spite of the complexities of working through the dis- steering (DIMUS; Anderson, 1957) with which the out- tant Physics Department at UCLA. puts from an array of independent sound receivers After less than two years as MPL director, Eckart’s (hydrophones) could be combined to provide simulta- attention was spread further abroad as he took on the neous parallel outputs focused in many different spa- directorship of Scripps Institution of Oceanography tial directions. These techniques led to rethinking of from 1948 to 1950. During that period he shifted MPL the nature of submarine sonar systems (Anderson and from the direct administration of the UC headquarters Spiess, 1959). to a division of SIO, as it has remained ever since. In While these two main lines of investigation were 1952 Eckart left for a sabbatical year at the Institute for the primary concerns, there were others leading to the Advanced Study at Princeton University. Upon his gradual broadening of the scope of MPL’s activities to return to Scripps he decided not to continue as MPL other aspects of experimental physics at sea and in the director and was replaced by Sir Charles Wright, who laboratory. Fred Fisher, who completed his University had retired to Canada after a career that included of Washington Ph.D. thesis with work conducted at directorship of the Royal Navy Scientific Service. After MPL, expanded Liebermann’s work on sound absorp- serving from 1952 to 1955 Sir Charles retired and was tion.