Satellites detect Millennium Tower sinkage

San Francisco’s Millennium Tower has tilted so much that the European Space Agency’s observational satellites can detect it from orbit.

In truth, that’s more a testament to the sensitivity of the orbital technology than to the state of the building.

Still, the fact that the Paris-based space program chose to train its 280 million-Euro orbital platform’s eyes on the leaning Yerba Buena landmark is a bit of a hallmark in itself, albeit one that a lot of people with ties to the building could do without.

But if it makes anybody feel better, they’re not alone: The ESA pinpointed quite a number of diminishing structures citywide.

In a report published last week, the ESA said that it trained radar from its pair of Sentinel 1 satellites onto San Francisco and compared the position of 301 Mission to imagery from the Sentinels’ previous glances at the city over the past two and a half years.

The radar employed is so sensitive that it can measure the position of a land mass down to the millimeter, and the ESA blog says that it’s particularly good at measuring the positions of buildings.

ESA

You can see the resulting images above. For the full effect, download the hi-res version here.

Points in green indicate that the land/buildings are more or less where the Sentinels expected them to be.

Yellow spots show where it has sunk a bit. Red spots indicate even more advanced sinkage.

The findings confirmed that the 58-story building is declining at a rate of “a few centimeters a year.” One centimeter is a little less than four tenths of an inch.

ESA

While most of San Francisco’s skyline has stayed put, blowing the image up reveals subtle shifting on thousands of parcels citywide. Although that’s probably not cause for alarm in most cases, as a little settling is normal.

The satellites also detected a significant swelling underneath Pleasanton—presumably from replenished groundwater stores after last winter’s rains.

Launched in 2014, the twin Sentinel satellites can capture images regardless of weather conditions, over swaths that can range from 50 to 250 miles.

So sensitive is the machinery, in fact, that it can even detect “the direction, wavelength and heights of waves on the open oceans.”

Or the subtle sinkage of a 58-story luxury condo on Mission Street.

• Satellites confirm sinking of SF Tower [ESA]
• Europe Observing System Ready [Spaceflight Now]
• Sentinel One User Guide [ESA]