Fiat lux: Mirrors flash sunlight from top of Campanile

Two solar reflectors that decorated the Golden Gate Bridge last year during its 75th birthday celebrations have now been installed atop one of UC Berkeley’s icons, the Campanile, which will soon celebrate its 100th anniversary.

The solar beacons are part of an art project designed and built by John Vallerga, who designs instruments for spacecraft at UC Berkeley’s Space Sciences Laboratory. Members of the public can go online to the Solar Beacon website to schedule three- or four-minute flashes from the mirrors anywhere – except for the campus itself – as long as it’s west or south of the tower and within sight of the Campanile’s spire.

“The light would be too bright for people as close as the campus,” Vallerga said.

The landmark Campanile, or Sather Tower, is more than 300 feet tall and visible from much of the Bay Area. Funded by UC Berkeley benefactor Jane K. Sather, it was completed in 1914-15 and has been a symbol of the Berkeley campus ever since.

What inspired Vallerga’s art project were the many reflections he saw throughout the day from his laboratory perch high above the Bay Area.

Dalton and Vallerga install heliostats on campanile.

Greg Dalton and John Vallerga install the heliostats on the roof of the Campanile. Photo by Robert Lettieri.

“Solar Beacon calls attention to sunlight and reflected light in people’s lives,” he said. “Plus, the idea that you can control a beam remotely is fun. When I talk to people, they get really excited by the fact that they can make an appointment for something far away and have it respond to them. They tell friends to watch the tower and it lights up at a specific time.”

The mirrors, or solar heliostats, were installed on the roof of the Campanile, or Sather Tower, during the first week of September, and remain out of sight from ground level. When the mirrors are not scheduled by a member of the public, they are programmed to shine on various Bay Area landmarks, including the new Exploratorium in San Francisco, the eastern end of the new Bay Bridge, the Emeryville marina and along Telegraph Avenue, which aligns with the Campanile.

Each heliostat is about two feet across and consists of four six-inch-square mirrors. The mirror assembly is attached to motors that swivel and tilt to send a reflected image of the sun anywhere within view of the Campanile. Commands are relayed to the heliostats via a hard-wired connection to the campus internet.

Vallerga hopes the project will create enough interest to generate support for a more elaborate art project involving prism heliostats that convert sunlight into refracted rainbow colors. He conceived this idea with London-based artist Liliane Lijn. The two have so far tried unsuccessfully to place these “spectro-heliostats” on mountain ridges or peaks in Europe and the sun-drenched Middle East.

“We would like to interest someone so we can improve the heliostats with prisms and get intense color,” Vallerga said.

Vallerga’s collaborators are UC Berkeley physicists Pat Jelinsky and Laura Peticolas; detector scientists Jason McPhate and Adrian Martin; mechanical engineers Greg Dalton, Joe Tedesco, Chris Scholz and Greg Johnson; system administrator Robert Lettieri; and science educators Ruth Paglierani, Dan Zevin and Kyle Fricke.

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