Everyone deserves a little bling on their 75th birthday.

That's what a UC Berkeley astrophysicist is bestowing upon the Golden Gate Bridge on May 27: a "bright bauble ... like a diamond necklace on a beautiful woman."

That bauble, in reality, is a pair of mirrors soldered to remote-control swivels on the western peaks of both the north and south towers, 750 feet above sea level.

The swivels - adjustable by anyone with a computer or smart phone - will point the mirrors at the sun, creating glimmering, flashing sparks of light.

"We think it'll be striking, on an emotional level," said John Vallerga, a principal research physicist at UC Berkeley's Space Sciences Laboratory. "It'll be strange-looking - a bright light where there shouldn't be one. Plus, it's just plain cool."

The contraption, called a heliostat, is about 3 feet tall and simple enough to be a high school science project. Vallerga and his pals at the lab paid for and manufactured it themselves, ordering the swivel from a military catalog and buying the mirrors from El Cerrito Glass. To hold the mirrors in place, they chose gold-colored aluminum as a nod to the bridge and, of course, the Cal Bears.

The project is one of dozens of public tributes to the bridge on its 75th birthday. They range from concerts to photo contests, but Vallerga's is one of only a handful that are actually attached to the bridge.

"Obviously, because the bridge is such an icon, we limited greatly what can involve the bridge itself," said Mary Currie, spokeswoman for the Golden Gate Bridge, Highway and Transportation District. "Our concern is about safety and security."

Although anyone can operate the heliostat, Vallerga limited its mobility so it won't flash at motorists on the bridge or on Doyle Drive. It probably won't be a distraction for airplane pilots or birds, either, because they'd only glimpse the lights for a moment before they vanish, Vallerga said.

Because the flashing would only be during the day, birds are not likely to become confused and fly into the bridge, said Arthur Feinstein, political chairman of the Sierra Club's Bay Area chapter.

In any case, the heliostat will be up for only three months, and not during a prime migrating period.

Vallerga and his cohorts came up with the idea at least a decade ago, while sitting in their Berkeley hills lab watching the nightly explosions of light and shadow as the sun set behind the Golden Gate Bridge.

"We'd look at the sun reflecting off the office widows in downtown Berkeley and Oakland and think, that's so cool - why can't we do that?" Vallerga said. "We can put cameras on satellites, why can't we put mirrors on the Golden Gate Bridge? I can't believe no one's thought of it before."

Working with the lab's artist-in-residence, Liliane Lijn, they concocted the heliostat - a simple device that they said merges art and science, allowing the public to interact with a world-renowned landmark.

"Initially, I liked it because it was a challenge," said Vallerga's colleague, aerospace manager Pat Jelinsky. "But then it was interesting because it was about more than just science."

The public can control the heliostat by going to solarbeacon.org and entering a specific time and GPS coordinates on a map of the Bay Area. Users can also choose a flashing sequence, in theory allowing them to send a brief Morse code message.

At the chosen time, the heliostat will triangulate between the sun and the user's location, flashing for 30 seconds or so.

The optimal viewing locations are any place with a clear view of the bridge towers, such as the Berkeley Marina, San Francisco waterfront or East Bay hills.

There are a few wild cards, Vallerga said. Will the mirrors become encrusted with salt and stop reflecting the sun? Will birds peck at it? Will winds knock it over? Will anyone care?

"To be honest, I have no idea what's going to happen," Vallerga said happily. "If it's foggy all summer, will people be mad at us? Maybe. We'll just have to see how this goes."
