SURVEYING THE OCEANS (HYDROGRAPHIC) 



35 



Airplane and equipment 



used in project MA GNET. 



east- west lines spaced approximately 200 miles apart. Averaging 

 well over 200,000 nautical miles of track annually, the planes 

 gather data necessary for the construction of reliable navigational 

 and world isomagnetic charts. In addition to measuring the 

 magnitude and direction of the earth's changing magnetic field, 

 scientists simultaneously measure cosmic radiation emanating 

 from outer space which enables them to describe the earth's field 

 at great distances from the earth. 



Since the development of this airborne capability, the two air- 

 craft have been in great demand to support many special 

 scientific projects. Among the more recent of these are extensive 

 fine-grain surveys (5-mile track spacing) of the Norwegian Sea, 

 the Reykjanes Ridge, the Eastern Continental Margin of the 

 United States, and a 100-mile strip across central United States 

 (a contribution to the USGS continental survey program), which 

 have provided valuable data on the nature and composition of the 



