I don’t always get to talk about details of work, but when it’s been cleared by someone in public affairs, then it’s “out there” and I get to link to it. This is an article about the backup clock facility in Colorado (also the GPS headquarters), which will be taking delivery of its first fountain clock in the near future. There’s a picture that explains how the fountain works that I drew up some time ago (and was improved upon by local peer review)
Though the newer fountain clock provides a stable signal, the equipment itself is very fragile.
“In order to get the Rubidium Fountain Clock into the master clock room at Schriever, the clock has to be floated, like a hovercraft, on a series of plastic mats until it reaches its destination,” Mr. Skinner said. “That prevents the bumping or jarring that might damage the equipment. Since it’s built in-house (at USNO) it would be hard to fix. You can’t just open a catalogue and order a new part.”
The “hovercraft” is, of course, the air sled I demoed a while back.