SF Chronicle article on Outdoor Exploratorium

by Eric on March 7, 2009

There’s a pretty lengthy article on the new Outdoor Exploratorium in today’s San Francisco Chronicle.

They include a list of some of the major exhibits featured at the Fort Mason site:

— Barnacles, tunicates, clams and rock crabs multiply on a thick log-like tube that can be winched up from the deep on command. The varied life forms show “zones of habitation” that depend on sunlight from above, water temperatures below, and salinity levels in between.

— An old and wobbling waterfront piling is equipped with a stylus that creates wave-like designs in the sand with each motion impelled by the wakes of passing freighters on the bay.

— A unique telescope with a calibrated lens is aimed across the water at the ruddy towers of the Golden Gate Bridge; the bridge becomes a thermometer as visitors peer through the telescope to measure its movements in warm days and cold.

— A string of red plastic arrows, lofted along a gleaming aluminum pole 35 feet tall, reveals the unimaginably complex patterns of the fretful winds that trouble the bay’s waters and give each of the city’s hills its own microclimate.

— A drinking fountain offers natural water diluted by varying levels of salt so people can observe and understand the changing salinity of the bay’s seawater caused by changing tides and rainy days.

The most fascinating exhibit to me is the “Bridge Thermometer:”

Among the most striking of the installations is the unique telescopic instrument focused on the Golden Gate Bridge, where a Global Positioning System has been installed to record motions of the bridge as small as 12 inches.

When temperatures rise at the Golden Gate, Doherty explained, the entire bridge expands; when temperatures fall, the bridge contracts. The bridge span itself can rise or fall as much as 16 feet, and an observer peering at the distant span through the calibrated eyepiece of the shore-based telescope at Fort Mason Center could actually observe the span’s changes as temperatures rise and fall hour-by-hour and day-by-day.

I’d like to know a little more about how they used GPS, presumably to measure the height variations for calibration.

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