After less than two years as MPL director, Eckart’s attention
was spread further abroad as he took on the directorship of Scripps
Institution of Oceanography from 1948 to 1950. During that period
he shifted MPL from the direct administration of the UC headquarters
to a division of SIO, as it has remained ever since. In 1952 Eckart
left for a sabbatical year at the Institute for Advanced Study
at Princeton University. Upon his return to Scripps he decided
not to continue as MPL director and was replaced by Sir Charles
Wright, who had retired to Canada after a career that included
directorship of the Royal Navy Scientific Service. After serving
from 1952 to 1955 Sir Charles retired and was replaced by Alfred
B. Focke, a Navy Electronics Laboratory group leader and chief
scientist for the nuclear depth-charge test, Operation Wigwam.
In 1957 Focke moved on to be chief scientist at Point Mugu Naval
Missile Test Center. Dr. Fred N. Spiess was appointed director
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 supporting 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 initial 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 than that
of the continents and revealed the surprising fact that the quantity
of sediment expected from millennia 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
subducted at plate boundaries, the accumulated sediment was cycled
onto and underneath the overriding plates.
On the signal-processing front, theoretical concepts quickly outran
hardware capabilities of the analog world and vacuum-tube computers.
At MPL there were imaginative efforts to build new devices, particularly
by Philip Rudnick and Victor C. Anderson, a group leader who had
been and MPL graduate student. Anderson was quick to see the opening
provided by representing the sonar signal by a close-spaced series
of polarity samples, resulting in the beginnings of digital-signal
processing—a major advance that provided the base for experimental
sonar installations, soon put to use in Navy operational systems.
The first of these was the delay line time compressor, a system
in which a simple digitized version of an acoustic signal could
be repetitively and rapidly played back as the basis for making
fine-scale correlation or frequency analyses over wide bands in
real time. The second was digital multibeam steering with which
the outputs from an array of independent sound receivers (hydrophones)
could be combined to provide simultaneous parallel outputs focused
in many different spatial directions. These techniques led to
rethinking of the nature of submarine sonar systems.
While these two main lines of investigation were the primary concerns,
there were others leading to the gradual broadening of the scope
of MPL’s activities to other aspects of experimental physics
at sea and in the laboratory. Fred
Fisher, University of Washington who completed his University
of Washington thesis with work conducted at MPL, expanded Leonard
Liebermann’s work on sound absorption: Spiess devised and
demonstrated a submarine tactical communication system and collaborated
with UCLA scientists in a program of measuring gravity at sea;
Liebermann developed and applied a new technique for measuring
fine-scale inhomogeneities in the ocean; and Rudnick collaborated
with other SIO scientists investigating radio-wave propagation
in the ocean.
One nonacoustic effort began with Sir Charles’s interest
in geomagnetism. On the 1952 Capricorn Expedition, Ron Mason had
used a ship-towed magnetometer adapted from a World War II airborne
system by Jeff Frautschy and others at Scripps. Sir Charles was
aware that the U.S. Coast and Geodetic Survey was being tasked
to make a dense seafloor topographic survey off the West Coast
of the United States and helped arrange it so that Mason could
tow the magnetometer from the survey ship and that MPL would provide
the necessary engineering support, which was led by Arthur Raff
who had previously been part of Russell Raitt’s group. The
result was the famous magnetic anomaly map demonstrating the existence
of bands of anomalously high and low magnetization having continuity
over hundreds of miles—the fundamental building blocks of
seafloor spreading and its successor plate tectonics. Subsequently,
Victor Vacquier, who had devised the airborne flux gate magnetometer
joined MPL and, refining the more robust proton precession magnetometer
approach, expanded MPL’s seagoing geomagnetic research program.
One other activity of importance was the involvement of senior
staff members (particularly Spiess and Anderson) in various Navy
research advisory committees and workshops that were instituted
to maintain fruitful interactions between the science and Navy
operational communities. This produced numerous dividends in motivating
new research directions and generating multi-institution collaborative
programs |
