Deep Sea Drilling Program - Coring Operations

Coring Operations

Although itself a remarkable engineering accomplishment, the Glomar Challenger was the site of many advances in deep ocean drilling. One problem solved was the replacement of worn drill bits. A length of pipe suspended from the ship down to the bottom of the sea might have been as long as 20,483 ft (6,243 m). The maximum depth penetrated through the ocean bottom could have been as great as 4,262 ft (1299 m). To replace the bit, the drill string must be raised, a new bit attached, and the string remade down to the bottom. However, the crew must thread this string back into the same drill hole. The technique for this formidable task was accomplished on June 14, 1970, in the Atlantic Ocean in 10,000 ft (3048 m) of water off the coast of New York. This re-entry was accomplished with the use of sonar scanning equipment and a re-entry cone that had a diameter of 16 ft (4.88 m) and height of 14 ft (4.27 m).

One major technological advance was the extended use of the holes after drilling. Geophysical and geochemical measurements were made during and after drilling, and occasionally long-term seismic monitoring devices were installed in the holes. This extended our understanding of the dynamic processes involved in plate tectonics. Another technological advance was the introduction of the hydraulic piston corer in 1979, which permitted virtually undisturbed cores of sediment to be recovered. This greatly enhanced the ability of scientists to study ancient ocean environments.

From August 11, 1968, to November 11, 1983, the Glomar Challenger achieved the following accomplishments: