The Space Launch Complex-3 site at Vandenberg Air Force Base in California. The West pad is nearest and East is in background. Photo: Lockheed Martin

Three months ago it was the historic Titan launch pad at Cape Canaveral. Now a California tower that aided rocket testing in the golden days of the space program will be demolished in the name of safety.

The A-frame mobile service structure that protected countless Atlas boosters at Vandenberg Air Force Base's Space Launch Complex 3-West will be toppled on Sunday.

The site could be used later this decade as the launch pad for futuristic Atlas 5 rockets, a new family of boosters being developed with the U.S. Air Force.

Lockheed Martin toppled the mobile service structure and umbilical tower at Cape Canaveral Air Station's Complex 41 last October. That pad is currently being refurbished as the East Coast launch site for Atlas 5.

At 4 p.m. EST (2100 GMT) on Sunday, engineers will use 20 pounds of explosives to blow out the tower's front legs, allowing the structure to come tumbling down.

"We are using the same demolition techniques as Complex 41, just on a much smaller scale," Lockheed Martin spokeswoman Joan Underwood said.

The structure, which hasn't seen a launch in nearly five years, was stripped of siding, wiring, cables and its hydraulic equipment over the past several months to prepare for the explosive event, which was tentatively planned for last fall.

"It serviced us well but it's just obsolete now," said Underwood.

But the demolition did not happen because Lockheed Martin was focused on rebuilding the Florida site, and now officials are concerned the SLC-3W tower is a safety hazard.

"It is basically a skeleton. We have to bring it down for safety reasons," Underwood said.

Lockheed Martin plans to dismantle and recycle materials from the tower after it is toppled. Doing such work while the structure was standing could be dangerous to workers.

What will become of SLC-3 West in the future is not yet clear.

"There is no rush to build anything at that site right now," Underwood said.

The nearby SLC-3 East pad was rebuilt a few years ago for the Atlas 2 series of rocket and saw its first launch in December.

Officials might opt to fly Atlas 5 rockets from a retro-fitted SLC-3 East instead of using SLC-3 West.