In 1959, the 230 foot tall trapezoidal tower was added to the top of the crane, bringing its total height to nearly 500 feet. The addition was created to facilitate Operation Skycatch, where Polaris Missiles were fired and caught via a string of arresting cables, before being lowered to the ground for testing. Previous versions of the test had the missiles flung out into the bay and retrieved from the ocean floor.
In the 1960’s the U.S. Navy’s underwater laboratory, SEA-LAB, was built and tested in Hunters Point waters. In the photo above we see the underwater habitat that was used for both SEA-LAB I and SEA-LAB II, before being adapted to SEA-LAB III.