Figure 10. View of uncoated sphere (No. 12) at 

 a depth of 2,790 feet after 431 days. 



be a 25-yard radius. To retrieve rhe clock, the 

 manipulator on RUM picked up the 5/8-inch chain to 

 which the clock was attached. Once on the surface, it 

 was learned that the clock was not retrieved. 

 Implosion forces must have "blown" the clock off 

 the chain. Hence, the time to implosion for Sphere 3 

 was not obtained; however, from information 

 obtained during the third inspection it has been 

 deduced that the sphere imploded during descent. 

 The Turtle operators thoroughly searched the Sphere 

 3 site for the clock, which was not located, but 

 observations showed that fragments of concrete were 

 spread over a radius of 50 yards. Also, the anchor 

 chain was not at the center of debris or at the loca- 

 tion of highest fragment density. This information 



Figure 11. View of coated sphere (No. 13) at 



a depth of 2,635 feet after 431 days. 

 Material on top of sphere is sediment. 

 Nylon rope on left side of sphere was 

 used to secure 5/8-in. chain around 

 sphere (see Figure 4). 



meant that the sphere probably imploded during 

 descent which allowed the fragments to disperse. 



In the case of Sphere 7, the fragments were all 

 located within a 10-yard radius. Sphere 7 did not 

 contain a clock, so the time to implosion is between 1 

 and 431 days. 



For Spheres 3 and 7, the Ps/Pj^, ratio was 0.72 

 and 0.58, respectively. This level of long-term loading 

 was considered relatively low for implosion to occur. 

 However, seven other spheres are subjected to Ps/Pj^ 

 ratios greater than 0.58, four of which have been 

 inspected and are performing well. 



The concrete control block for Sphere 3 was 

 retrieved. The compressive strengths of this block and 

 other control specimens stored at on-land field 



11 



