When a military surveillance balloon broke free of its moorings Wednesday at Aberdeen Proving Ground and began a 160-mile journey north, it was only the most dramatic in a series of problems for a deeply troubled $2.7 billion Army effort to mount powerful radars high in the skies.
The two-balloon system, known as JLENS, was launched over Maryland in December as part of a three-year test. The balloons are supposed to stay anchored to the ground by 10,000-foot cables, but authorities said one of the pair came unhitched around noon and floated toward Pennsylvania.
The military scrambled a pair of F-16 fighter jets to track the unmanned balloon, which dragged 6,700 feet of cable that snapped power lines in Pennsylvania and cut electricity to thousands of customers. The balloon finally came to rest near tiny Moreland Township, Pa., after about four hours on the loose, authorities said.
Online, the impromptu flight became a national source of amusement, with commentators on social media, including former NSA contractor Edward J. Snowden, following its slow progress and cracking jokes. On television, live footage tracked the balloon's journey.
The Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System program was designed to watch for and direct fire on incoming cruise missiles and other threats. NORAD is testing its effectiveness in the capital region.
But a Tribune Newspapers investigation reported last month that the 17-year effort to develop the system had created an unkillable "zombie" program beset by high costs, low reliability and questionable performance.
Defense Department authorities have not said precisely how the balloon got loose, and a NORAD spokesman did not respond to questions about what the incident might mean for the future of the program. In brief comments at the Pentagon, Defense Secretary Ashton B. Carter said bad weather could be to blame.
Poor conditions have caused problems for JLENS in the past. In 2010, a JLENS balloon was destroyed when it collided with a blimp during a storm in North Carolina.
The company that makes the balloons, Columbia-based TCOM, says they can operate in winds up to 80 mph. While Tuesday was rainy, winds gusted no higher than 23 mph around Aberdeen Proving Ground, according to the National Weather Service.
Raytheon, the contractor that runs the program, has said in publicity materials that the cable is unlikely to break.
"The chance of that happening is very small because the tether is made of Vectran and has withstood storms in excess of 100 knots," the company said on its website. Vectran is a polymer that its manufacturer says is five times as strong as steel.
A Raytheon spokesman declined to comment, and TCOM did not respond to a request for comment.
Pennsylvania Gov. Tom Wolf said he had teams keeping an eye on the balloon's progress, and authorities warned people to stay away if they saw it and to call police. The balloon reached heights of 16,000 feet, making it difficult to spot in the cloudy skies. Then social media reported sightings near Bloomsburg, Pa.
According to eyewitnesses, the tether that trailed the escaped balloon raked across the Pennsylvania countryside and townships, ripping through power lines. About 27,000 people lost electricity, the local power company said.
Holly Starr was at her home in central Pennsylvania when she noticed something drifting by, she said in an interview. She went outside and snapped a picture of the errant military balloon floating over a red barn, a rolling country road and trees decked in fall colors.
"Within probably a minute my power went out," Starr said. She thought the strange craft must have come from a nearby car dealership until she went online and saw her friends chattering on Facebook.
Starr said she didn't hear the F-16 fighter jets from an Air National Guard base in New Jersey, and soon the balloon passed silently on.
Michael Kucharek, a spokesman for NORAD, said the balloon had lost some of the helium that keeps it afloat and drifted to the ground before 4 p.m. A Pennsylvania State Police spokeswoman said there were no reports of injuries.
As the balloon lay deflating on the ground, a specialized military team was dispatched to recover it while troops from the Pennsylvania National Guard secured the crash site.
While it was the balloon portion of the JLENS system that attracted attention Wednesday, the key to its capabilities are sophisticated radars and information links to the ground designed to spot threats and coordinate with anti-air missiles.
The balloons operate in pairs known as orbits. One carries radars to detect danger and the other has gear to lock on to a target.
Their effectiveness has been questioned. In tests, the system has struggled to separate friend from foe, and software problems have made it difficult for the balloons to communicate with other parts of the nation's air defenses, the Tribune investigation found.
Army leaders tried to kill the program in 2010, but it has lumbered on with the help of a lobbying campaign in Congress.
In April, the program had a chance to prove itself when a Florida postman flew a small gyrocopter from Pennsylvania to Washington in a plea for campaign finance reform. It was just the kind of threat JLENS was supposed to detect — but it didn't because it turns out the test system was not fully operational at the time.
That debacle prompted lawmakers to question how the man was able to land — undetected by JLENS — on the West Lawn of the Capitol.
Baltimore Sun reporter Scott Dance contributed to this article.