140-foot high drilling derrick which is capable of supporting up to 

 24,000 feet of drill pipe. A computer controlled dynamic positioning 

 system can maintain Challenger over a drill site in water as deep as 

 22,500 feet. This system controls a series of auxiliary thruster 

 engines which, combined with the main engines, furnish the power 

 to maintain position relative to an acoustical beacon that is emplaced 

 on the sea bed adjacent to the drill site. As a result of its proven 

 effectiveness in extreme weather and sea states, dynamic 

 positioning has now been installed in several ships that are used by 

 the petroleum industry for offshore drilling. In order to allow reentry 

 of bore hole after replacing worn out drill bits, a sonar guided reentry 

 system was designed and has been employed successfully at several 

 sites. The most recent technological improvement of the drilling 

 system is a heave compensator, which is designed to isolate the drill 

 string from the vertical heave of the ship. As a result, soft sediment 

 cores are less distorted and drill bits last longer when penetrating 

 harder rocks. This system was installed in November 1973 and 

 successfully used for the first time in December 1973. 



The enormous contributions of the DSDP to geologic and 

 oceanographic knowledge have now established it internationally as 

 one of the most important and productive earth science 

 investigations ever undertaken. Having nearly completed a broad 

 reconnaissance of the Atlantic, Pacific, and Indian Oceans, the 

 Mediterranean, Caribbean, Bering, and Red Seas, and the Gulf of 

 Mexico, drilling was accomplished in the hostile environment of the 

 antarctic last year, an important operational as well as scientific 

 achievement. Samples and data from 31 legs are now being studied 

 by over 300 scientists throughout the world. Table No. 1 lists some of 

 the significant operational statistics of these legs. 



' Current institutional members of JOIDES are: Lamont-Doherty Geological 

 Observatory, Columbia University; Rosenstiel School of Marine and Atmospheric 

 Science, University of Miami; Scripps Institution of Oceanography, University of 

 California, San Diego; P. P. Shirshov Institute of Ocsanology, U.S.S.R. Academy of 

 Sciences; Department of Oceanography, University of Washington; Woods Hole 

 Oceanographic Institution; Bundesanstalt fur Bodenforschung, Federal Republic of 

 Germany. 



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