There’s a mysterious object standing in a parking lot just eight miles south of downtown Seattle. From the surface, it looks like a grayish-green dome on a pile of rubble. But dig a little deeper and you’ll discover a forgotten link to Seattle’s Cold War past. Retired Boeing engineer Dan Witmer is one of the few remaining people in Seattle who knows what that dome is covering up: a defunct Minuteman missile silo. Cuban Missile Crisis Hits Seattle Witmer says East Marginal Way looked a lot different in 1962. That’s the year when he started working for Boeing as a newly minted engineer. It’s also the year that the US discovered Soviet missiles in Cuba, bringing the world to the brink of nuclear war. President Kennedy went public with the news on October 22, 1962. Witmer remembers the Cuban Missile crises. He can still picture the line of extra food cans he and his wife stockpiled in his Bellevue apartment. But there’s another image that stands out even more: the image of crawling down inside a tube about 70 feet deep containing a Minuteman missile. It was part of Boeing’s developmental center, located across the street from the present-day Museum of Flight. Today, remnants of the old silo are still visible in a parking lot off East Marginal Way. “You got down inside the silo by going down a ladder. It was like going down a ladder in a submarine. The missile sat in the middle. I wouldn’t say it was an eerie sort of thing; it was just our place of work.”

Satellite image of the missile silo, circled in yellow View in larger map. Hundreds of missile silos like this were being built in rural areas around the country in the 1960s. Those had live nuclear missiles inside. This one was different; it was a primary testing site. The idea was that if anything was going to go wrong in the field, Boeing wanted it to go wrong here first. That way, engineers like Witmer could come up with solutions. In 1962, Witmer says there were a lot of problems to troubleshoot.

What’s Sending Missiles Off Target? Witmer spent a lot of time puzzling over problems in the Minuteman missile’s guidance system, which would get a missile from its launch point to a target half way around the world. The technology was complex and cutting edge. But it relied on the same ancient navigational tool that mariners once used: The North Star. “There was a special little tube that came down from the surface of the ground,” Witmer explains. “This tube was lined up with the North Star. So it would look up there with an instrument equivalent to a surveyor’s transit.” Engineers used the tube to help measure angles, make calculations, position mirrors, and eventually shine a light beam into the missile to tell it where to go. But there was a problem. The engineers started noticing that the critical angles between the missile and the North Star began to change from day to day. They suspected the misalignment was caused by tidal movement in the Duwamish River. Witmer tracked the changes to see if there was a meaningful correlation, but it turned out to be more likely caused by heavy traffic on nearby train tracks.

Cascade Snow Shapes National Security Another issue Boeing engineers turned their attention to was the silo lids. They wanted to make sure the lids would be able to open correctly under all kinds of conditions. “By 1962, they had begun to put some of these missiles out in Montana, and they were worried about the snow piling up on the lid,” Witmer says. The test engineers worried that if too much snow and ice accumulated, the lid might jam and prevent the missile from launching. Witmer and his fellow engineers needed to run some tests. “In order to do that, we needed some snow,” Witmer says. “They ended up getting snow from Snoqualmie Pass and hauled it down here in dump trucks, down through Seattle.” The tests confirmed the engineers’ fear: Certain levels of snow did prevent the lid from opening properly. The engineers tried installing steel teeth on the lid to crush through the ice. They also experimented with special bumpers to push snow drifts aside.

As they worked, a story started circulating about a temporary solution being used in the field. Maybe it was a tall tale; Witmer’s not sure. “They decided to deal with the problem by putting horse manure out in front of the lid, so as it gradually cooked and degraded, the heat would keep the snow from ever piling up in the first place,” Witmer says. A matter of national security comes down to horse poop. The Little Red Light Witmer says the most exciting challenge came one night when his team kept getting an error that completely stopped the launch sequence. It was a serious problem. It meant that all those Midwest silos simply wouldn’t be able to launch missiles should President Kennedy give orders to strike. It all came down to a tiny red light.