The main building in the foreground is the Systems Technology Test Facility. This was originally used during the Nike-X program to test the Missile Site Radar, which is installed on the white pyramid, just left of center. The rails extending to the ground allowed maintenance using a system similar to a window-washing elevator. Nike-X evolved into Sentinel, then Safeguard, and then the entire ABM effort was shut down after the 1972 ABM Treaty.

In the later 1970s, fears grew that the Soviets might "break out" of the ABM Treaty. To counter this possibility, the Army began development of the Site Defense Program, which would incorporate a radar similar to the MSR but using newer electronics, and an updated missile known as Sprint II. The new Site Defense Radar (SDR) was built on the smaller building just to the right of the original MSR in 1977, and operated until 1980. No Sprint II missiles were built, and the program switch to focus on technology development instead of testing.

The island was backfilled to make room for the SDP buildings, and the filled in area can be seen in this image as the light colored ground on the right side. The two metal fences on the lower left of the image reflected the sidelobes of the original MSR away from the built-up area for the missile silos, which is off-frame to the left.