Nike

Started: 2022-07-07 21:56:20

Submitted: 2022-07-07 23:24:45

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Visiting the Nike missile site in the Marin Headlands

After visiting the Titan missile silo outside Tucson, I decided it was time to take Calvin to the Nike missile site in the Marin Headlands; and while I was at it I took the rest of my family and arranged to meet Willy there, since I could kind of squint and get the idea that the Marin Headlands were equidistant between Santa Cruz and Angwin. I first visited the battery six years ago, so it seemed like it was time to visit the site again.

We drove to the Marin Headlands on Saturday morning, the 7th of May, crossing the Golden Gate Bridge as the fog parted, drove through the one-lane tunnel into the protected valley at the heart of the headlands, and met Willy in front of the visitor's center. The visitor's center had apparently permanently closed at some point since my last visit (four or five years ago), which explains why I couldn't find it on the park's website, but doesn't explain why Google Maps still listed open hours.

We ate lunch with a view of the Golden Gate Bridge, then walked into Battery Wallace to look at the massive reinforced-concrete casemate covering the gun pit (now filled with sand), and look out at the older coastal defense batteries on the surrounding hills.

Golden Gate National Recreation Area staged an "open house" at the Nike missile battery on the first Saturday of the month with people who had worked at Nike missile sites while they were active. This meant that, instead of a guided tour to keep us moving and answer the right questions at the right time, we had to wander around and find people and figure out the right questions to ask them to get them to tell their spiel about whatever they were standing in front of.

This only got really interesting when we got to visit and go inside the guidance vans that managed the target acquisition, launch control, and missile guidance for the site. The guidance controls were originally placed on the top of the adjacent hill across the valley. (This picture is from my first visit six years ago; they're still in the same place, but when we visited this time the doors were open so we could enter both vans.)

Originally the Nike missile program had been designed to be mobile in the field, with the missiles themselves carried around on mobile launchers and the guidance and control centers carried around on trucks (hence the designation "vans"), but the electronics in the guidance vans were not up to the stress of bumping around roads so Nike transitioned to permanent emplacements. (This mobility did make it easy to move the guidance vans down to the launch facility.)

We visited the further van first, which contained the target acquisition and launch control systems. When the program was in operation, it would have been given targets from a centralized control computer, with each missile site assigned different aircraft in the attacking bomber squadron. The target acquisition radar would acquire the planes and identify the specific aircraft it had been assigned; then the target tracking radar would lock onto that specific aircraft and feed its position to the guidance computer.

The guidance computer was a sight to behold. It was housed in several cabinets stuffed along the wall of the guidance van, with scores of vacuum tubes mounted neatly on the door of the cabinet, all wired together in the back. (In the picture above the cabinet door is open at the right, and we're looking at wiring harness at the back of the door and the components inside the cabinet on the left.) Each group of tubes built an op-amp, and they were wired together to form a closed-loop feedback-and-control system. (For a brief moment I flashed back to my day-job building closed-loop control systems in software, using the same basic principles.)

It was an analog computer, built painstakingly by hand. It was simultaneously mind-bogglingly complex while also hopelessly obsolete. There's more compute power in my Bluetooth earbuds, but all the parts and wires were spread out in front of me and I thought, just for a moment, that maybe I could understand the whole thing from first principles if I remembered the right things from my undergrad circuits class.

There was one essential operation the analog op-amps couldn't do on their own, and that was multiply. To correctly time the flight of the missile towards its target, the guidance computer needed an elaborate series of mechanical wheels, made of precision-machined aluminum and kept in sealed containers that slid out from the next cabinet like drawers.

We left the guidance vans and made our way down into the missile battery itself, where another missile man was showing the Nike Hercules missile on its elevator, ready to be raised to the surface to launch position.

The missile itself — the whole reason this site existed at all — was an ugly beast: an angular upper stage bolted on top of an awkward solid-fueled boost stage. But it worked, and that was good enough to put it into service to fend off an existential threat.

Calvin seemed enthralled; Julian somewhat less so (but he did appreciate the ear protection I brought for him for this very room).

We left the missile site and headed back towards home, stopping on an overlook on the shoulder of Hawk Hill, overlooking the Golden Gate Bridge framing the city of San Francisco behind it. Julian took the opportunity to point out the bridge for me.

While I was standing on the overlook three separate groups asked me to take pictures of them with the bridge behind them. (It's possible I signaled "I can take pictures" by wearing a DSLR around my neck; one of the groups had their own DSLR.)

Then we headed back home to Santa Cruz, having visited a local Cold War relic.

All of the pictures I took at the Nike missile site in the Marin Headlands are here: Photos on 2022-05-07.