When the weather's good, a strange speck will be visible on the Baltimore skyline: a giant balloon the Army is floating high above Middle River to scan for cruise missiles.
The balloon — technically an aerostat because it's tethered to the ground — is expected to launch Saturday. It's one of a pair planned for the skies over Maryland to test sensors that can detect and train fire on cruise missiles from hundreds of miles away.
They're aimed at filling what some military officials see as a gap in U.S. air defenses. But the program has been beleaguered by shrinking budgets and opposition from privacy advocates, who warn that the balloons could be transformed into ever-present eyes in the sky, watching the movements of everyone for miles around.
Aberdeen is hosting the balloons for a three-year test. Officials stress they will not carry cameras.
The Army showed off the first helium-filled balloon last week at an Aberdeen Proving Ground annex. The gleaming white, 80-yard-long inflatable hovered just above a wide patch of gravel, where it was free to swing about in the breeze.
At the briefing, Capt. Matt Villa, a planning officer with the Army, attempted to assuage concerns.
"I can't stress enough there are absolutely no cameras or video equipment on board … the system," Villa said. "Its radars cannot detect people, it does not store information … it has no weapons on board."
The military's stated intentions notwithstanding, privacy advocates say the balloons, which can float 2 miles in the air for up to a month at a time, could easily be turned into powerful spying platforms. David Rocah, an attorney with the American Civil Liberties Union of Maryland, described them as the latest example of battlefield technology being brought home for domestic use.
"They enable a kind of persistent surveillance which is not technologically feasible by other means," he said. "It is that persistence that creates the invasion."
The Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System — or JLENS — uses sophisticated radar to stare out 340 miles in every direction in search of cruise missiles and other airborne threats.
The balloons work in pairs: One looks for potential threats; the other helps weapons lock onto those threats and, it is hoped, shoot them down. The second balloon is set to rise over Edgewood early next year.
Data from the sensors are passed down to the ground through the tether and on to Aberdeen Proving Ground.
Supporters of JLENS say it will provide long-range radar much more consistently and cheaply than systems mounted on planes.
Maj. Gen. Glenn Bramhall, whose unit oversees the project, told reporters that cruise missiles are becoming more widely available to U.S. enemies. Chet Nagle, a former Navy aviator and member of the lobby group the Committee on the Present Danger, said the test will leave Washington better defended against a cruise missile attack.
"There is nothing else we have that will do that," Nagle said. "Most of our in-place defensive systems are designed for ICBMs," he said, referring to the much higher-flying intercontinental ballistic missiles.
In a research paper, Nagle pointed to flights by Russian Bear bombers close enough to the United States that they could reach Washington with a cruise missile. Other hostile nations could obtain a ship-mounted missile, Nagle wrote.
Still, JLENS has seen its scope and funding narrowed.
Defense officials originally wanted to field as many as 16 of the balloon pairs. But after costs spiked, the program was scaled back, and the pair above Maryland now look to be the only ones in operation.
If the test proves successful, Bramhall said, the program could be expanded. But the House of Representatives attempted to slash by half the $54 million proposed budget for JLENS in this year's National Defense Authorization Act. The legislation signed by President Barack Obama this month restored most of the money, but Bramhall's team will have to make do with about $12 million less than it asked for.
The project has also been dogged by concerns about privacy, despite repeated statements by the military that the balloons will not be used to track people on the ground and will not carry video equipment.
The Electronic Privacy Information Center sued the Army for documents on the program. Files dating to 2009 and disclosed this year show that, originally, the Army did want the balloons to carry cameras.
Raytheon, the company that makes the system, has promoted its ability to use JLENS to track targets on the ground, including individual people.
NORAD spokeswoman Maj. Beth Smith said the idea of putting cameras on the balloons has been abandoned.
"That requirement was stripped in the final project specs," she said. "JLENS as built and delivered has no cameras."
But Ginger McCall, an attorney with the privacy center, said the Army has not turned over any documents to indicate an official no-cameras policy.
McCall said it is difficult to know exactly what the capabilities of JLENS are — and that uncertainty, combined with the balloons' presence on the horizon, could cause people within range of its sensors to change their behavior.