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satellites orbiting round the earth have provided scientists with a vast amount of information about conditions in outer space. by comparison,relatively little is known about the internal structure of the earth.it has proved easier to go up than to go down. the deepest hole ever to be bored on land went down 25,340feet-considerably less than the height of mount everest drilling a hole under the sea has proved to be even more difficult.the deepest hole bored under sea has been about 20,000feet .until recently,scientists have been unable to devise a drill which would be capable of cutting through hard rock at great depths.

this problem has now been solved.scientists have developed a method which sounds surprisingly simple.a new drill which is being tested at leona valley ranch in texas is driven by a turbine engine which is propelled by liquid mud pumped into it from the surface.as the diamond tip of the drill revolves,it is lubricated by mud .scientists have been amazed to find that it can cut through the hardest rock with great ease.the drill has been designed to bore through the earth to a depth of 35,000feet.it will enable scientists to obtain samples of the mysterious layer which lies immediately below the earth's crust.this layer is known as the mohorovicic discontinuity,but is commonly referred to as the moho.