Project Mohole was an attempt in the early 1960s to drill through the Earth's crust to obtain samples of the Mohorovičić discontinuity, or Moho, the boundary between the Earth's crust and mantle. The project was intended to provide an earth science complement to the high-profile Space Race. While such a project was not feasible on land, drilling in the open ocean was more feasible because the mantle lies much closer to the sea floor.
Led by a group of scientists called the American Miscellaneous Society with funding from the National Science Foundation, the project suffered from political and scientific opposition, mismanagement, and cost overruns. The U.S. House of Representatives defunded it in 1966.Mohole, LOCO, CORE, and JOIDES: A brief chronology Betty Shor, The Scripps Institution of Oceanography, August 1978, 7 pp. Retrieved June 25, 2019. By then, a program of sediment drilling had branched from Project Mohole to become the Deep Sea Drilling Project.
Background
During discussions at the end of a panel reviewing proposals for Earth Sciences at the National Science Foundation in March 1957, Walter Munk, a professor of geophysics and oceanography at the Scripps Institution of Oceanography, suggested the idea behind the Mohole Project: to drill into the Mohorovicic Discontinuity and obtain a sample of the Earth's mantle. The suggestion, in response to the set of fine, but modest, proposals they had just reviewed, was made as a bold new idea and without regard to cost.Interview with Dr. Gordon Lill Van Keuren, David K., History Office, Naval Research Laboratory, March 20, 1995, 44 pp. Retrieved June 25, 2019. Harry Hess, a professor of geology at Princeton University, was receptive to the idea.
Hess was one of the principal proponents of sea-floor spreading or plate tectonics at the time, and he saw the Mohole Project as a means to test this theory. The project was to exploit the fact that the mantle was much closer to the ocean's floor (5–10 km) than to the surface of land over continents (ca. 30 km), suggesting that drilling to the mantle from the ocean would be more feasible.
The idea for the project was initially developed by the informal group of scientists known as the American Miscellaneous Society (AMSOC), including Hess, Munk, Gordon Lill, Roger Revelle, Harry Ladd, Joshua Tracey, William Rubey, Maurice Ewing, and Arthur Maxwell. Lill, who headed the Geophysics Branch of the Office of Naval Research, had formed this whimsically-named society to assist in processing a disparate variety of proposals (of a miscellaneous nature) for funds in the earth sciences. Hess had approached Lill with the Mohole idea, and they eventually decided that AMSOC should submit a proposal to the National Science Foundation to develop the project. The name of this organization was often viewed as a joke, however, and it would later prove troublesome to the project's success.
The initial proposal to NSF was rejected because of the informal nature of the originating organization, and it had to be resubmitted as a proposal from the National Academy of Sciences (NAS); several members of AMSOC were also members of NAS. The proposal resulted in a $15,000 grant in June 1958 for a feasibility study of Mohole, and Willard Bascom, an ocean engineer, oceanographer, and geologist, became the Executive Secretary of AMSOC.
On October 4, 1957, the Soviet Union launched the Sputnik 1 satellite that initiated the Space Race and a revolution in science and education in the United States.The Legacy of Sputnik [Editorial]. (2007). The New York Times, p. 28. The ever-present competition with the Russians provided a positive political background to the Mohole Project, particularly after rumors that the Russians were attempting a similar drilling program. Other aspects favorable to Mohole were that it was the first big science project in Earth Sciences and that it was a new idea distinct from the many space programs that were underway as a result of the Sputnik crisis; the National Aeronautics and Space Administration (NASA) was established in 1958.
With the new funding, AMSOC formed three panels in 1958: the Drilling Panel, the Site Selection Panel, and the Scientific Objectives and Measurements Panel, and in April 1959 Bascom became the Technical Director for the Mohole Project. The AMSOC Committee, within the National Academy of Sciences, became both advisor and manager for the project. By mid-1959, the NAS Governing Board had given AMSOC authorization to proceed with preliminary studies and Phase 1 of Mohole with a budget of up to $2.5M. Project Mohole was to proceed in three phases: Phase 1, an experimental drilling program; Phase 2, an intermediate vessel and drilling program; and Phase 3, drilling to the Moho.
Phase 1
Phase 1 was executed in early 1961, with innovative ocean engineering culminating in test bore holes. Led by Bascom, Project Mohole contracted with Global Marine of Los Angeles for the use of its oil drill ship CUSS I. The name of the drill ship was derived from the consortium of oil companies that had developed it in 1956, Continental, Union, Superior and Shell Oil. The ship was to be a technological test bed for the nascent offshore oil industry. CUSS I was one of the first vessels in the world capable of drilling in deep water, though it had been limited to depths of 100 m or a few hundred feet. Project Mohole expanded its operational depth by inventing what is now known as dynamic positioning. By mounting four large outboard motors on the ship, positioning the ship within surrounding moorings using acoustic techniques, and guiding the motors by a central joy stick, CUSS I could maintain a position within a radius of . Such unprecedented position keeping enabled the drilling to occur in deep water.Van Keuren, David K., An Interview with Dr. George and Betty Shor , History Office, Naval Research Laboratory, March 16, 1995, 55 pp. Retrieved June 26, 2019.
With William Riedel as chief scientist, initial test drillings into the sea floor occurred off Guadalupe Island, Mexico, in March and April 1961. The event was documented by John Steinbeck for an article in Life magazine. The location was determined based on world-wide seismic refraction studies by George G. Shor and others, and its proximity to San Diego, where CUSS I was located. A recent such study by Shor near Guadalupe Island had shown that the sea floor of the area had interesting layering features, suggesting the drilling could confirm properties derived from the seismic studies. The layers were of geologic interest in their own right.
Five holes were drilled, the deepest to below the sea floor in of water. This drilling was unprecedented: not because of the hole's depth, but because an untethered platform in deep water was able to drill into the sea floor. Also, the core samples proved to be valuable, penetrating through Miocene-age sediments for the first time with the lowest consisting of basalt. This lowest layer, of volcanic origin, confirmed the properties derived by the seismic studies. This test drilling program was seen by all as a great success, attracting the attention of both the scientific community and the oil industry. The test was completed in a timely manner and under budget, costing $1.7M.
Bascom reviewed the geologic science behind the Mohole Project, the required drilling engineering, and the CUSS I test drills in his book A Hole in the Bottom of the Sea, published in 1961.
Robert Ballard, in a talk at Wayne State University in 1969, stated that as far as he was concerned, the goal of the project was never to drill down to the Moho. It was to develop the technology to drill holes in deep water with a rig that was not tethered to the bottom.
Controversy and cancellation of later phases As Munk commented in 2010, the success of Phase 1 of Mohole doomed the project. The many factors that proved fatal to Mohole included the human element, differing views of the engineering and scientific goals, political improprieties at the governmental level, complexities of managing such a large project, and escalating costs. D. S. Greenberg, a reporter for the journal Science commented in 1964, "There is a lengthy and unattractive trail of bickering, bitterness, and shortsightedness, involving some of the leading figures of American science and science administration." The drilling that was to occur in the second phase of the project never took place.
Scientific goals Scientists involved with Mohole had differing and irreconcilable views as to the scientific goals of Mohole. Part of this disagreement resulted from a long tradition of competition among the four main oceanographic institutions: Lamont Geological Observatory in New York, the Woods Hole Oceanographic Institution in Massachusetts, the University of Miami in Florida, and the Scripps Institution of Oceanography in California. The competitive nature of these institutions meant that they often refused to cooperate. The East Coast institutions favored a drilling site in the Atlantic Ocean or Caribbean, while Scripps in San Diego favored a North Pacific site. Any site had to be near a large port to make the logistics of the large expedition feasible, it had to have a Moho as shallow as possible, it could not be in a geologically active region, and it had to have stable weather conditions. In January 1965 a site north of Maui, Hawaii, was selected.
A critical dispute was whether Mohole should begin at a modest, conservative pace with a program of drilling shallow bore holes in sediments, or whether it should proceed at once to drill the deep hole to the Moho. The issue was critical since the two approaches required differing engineering, management, and allocation of resources. There was significant interest in a program of shallower holes from those in the oceanographic community and the oil industry. The deeper hole addressed more fundamental questions about the structure of the Earth. Some viewed the more modest initial approach as developing essential engineering and drilling techniques that would later be required for the deep bore hole.
Some in the geology and geophysics communities objected to Mohole because, for its enormous cost, they expected that not much would be learned from drilling. They viewed the project as an engineering stunt of little scientific value.
Management During the CUSS I test and shortly thereafter, the Mohole project was managed by the National Academy of Sciences, with AMSOC acting as an advisor. The informal AMSOC group was insufficient to manage what was expected to be a large project in its next phase, and the National Science Foundation (NSF) took over management of the project in late 1961. AMSOC was retained as an advisor to NSF. During late 1961 and early 1962, NSF sought bids from universities and private industry for a prime contractor for Mohole.
Hollis Hedberg, a geologist from Gulf Oil Corporation and professor of geology at Princeton University, chaired the AMSOC Mohole committee from December 1961 to November 1963. Hedberg had significant experience in drilling in the oil fields of Venezuela in the 1940s. Hedberg strongly advocated an initial program for drilling shallower holes, and a second program for drilling to the Moho.
Since many members of AMSOC worked for universities or industries developing bids for Mohole, many of the scientists on AMSOC resigned to avoid conflicts of interest. Bascom and his associates formed a corporation, Ocean Science and Engineering, Inc., expecting that they would continue the work demonstrated in the CUSS I test. Gordon Lill resigned from AMSOC, since his employer was Lockheed and was vying to become the prime contractor. Roger Revelle similarly resigned.