Updated Wednesday, October 28 at 3:31 p.m.

A missing military blimp has descended somewhere in central Pennsylvania and is near the ground. NORAD tweets:

If you see a large, cigar-shaped white balloon in the sky, you’re not seeing things, but you should get in touch with 911.

An unmanned JLENS blimp has come unmoored at the Aberdeen Proving Ground, in Maryland near Baltimore. (That’s “Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System,” which explains why they use the acronym.) The blimps—technically aerostats, which are helium balloons tethered to the ground—are stationed at the Army facility, where they can detect cruise missiles, airplanes, drones, and vehicles on the ground, with a range of 340 miles.

In theory, and when they’re tied down, that is. Some time around 1 o’clock Wednesday afternoon, one them came loose. The 242-foot blimp isn’t a cheap piece of equipment, either. The average cost of the Raytheon-made airships is around $175 million dollars. In 2010, a civilian balloon broke loose and destroyed a blimp on the ground that had run $182 million.

As The Baltimore Sun noted in a devastating investigation last month, the blimps haven’t really performed anywhere near as hoped:

After 17 years of research and $2.7 billion spent by the Pentagon, the system known as JLENS doesn’t work as envisioned. The 240-foot-long, milk-white blimps, visible for miles around, have been hobbled by defective software, vulnerability to bad weather and poor reliability … JLENS is a stark example of what defense specialists call a “zombie” program: costly, ineffectual and seemingly impossible to kill.

In its most high-profile failure, the system failed to spot the postal worker who flew an gyrocopter onto the Capitol lawn in 2014, just the sort of incursion the blimps were meant to spot.

In an FAQ posted online, Raytheon assured readers that it was unlikely the aerostats would come untethered: “The chance of that happening is very small because the tether is made of Vectran and has withstood storms in excess of 100 knots. However, in the unlikely event it does happen, there are a number of procedures and systems in place which are designed to bring the aerostat down in a safe manner.”

The escaped aerostat has launched many a mocking tweet, and even gotten Edward Snowden’s attention:

Blimps may seem harmless and silly, but it’s hard out here for a blimp. The JLENS’s struggles notwithstanding, airships have a long, noble, and sometimes tragic history serving U.S. national defense. Following German deployments of Zeppelins against Britain in World War I, the U.S. began toying with rigid airships in the 1920s. The U.S.S. Shenandoah flew for two years before crashing in a storm in 1925, killing 14.

In 1921, the Navy’s smallest blimp broke loose and went on what The New York Times described as a “rampage,” drifting for more than three hours at a height of 5,000 feet before peacefully coming down on a farm in Scarsdale, New York.

The U.S.S. Akron, which flew in the 1930s, was the world’s largest helium airship and the first flying aircraft carrier; it could launch an airplane. (The ship was named for its hometown in Ohio, where Goodyear built it. The tire company still builds its signature blimps there, though the newest is actually a semi-rigid airship.) Here’s the Akron launching a plane during tests:

U.S. Navy

But the Akron crashed in 1933, killing 73 of 76 crew members. During World War II, the military made more than 150 more blimps in Akron, which were used as effective escorts for ships, because they could spot submarines.

Now, however, the hunter has become the hunted. Rather than assisting the military in stopping attacks—whether from submarines or from cruise missiles aimed at Washington—NORAD has scrambled two F-16s to track the airship as it drifts away from Aberdeen, headed toward Pennsylvania, perhaps confused about how to get to the World Series in Kansas City. Who’s laughing at the blimp now?