New sensors taking old-fashioned ride over Pax
By James Darcy

PUBLIC AFFAIRS

Blimps are the jolly fat men of modern aviation, seen in the mind's eye presiding over football games and festivals, offering sky-cams and conspicuous product placement as their principal raison d'etre. But if STI Government Systems is right, airships could soon restore their latter-century image as symbols of military power, amply capable of both saving and ending lives. Over the last two months, STI has used Pax River as a staging area for tests and demonstrations of an airship equipped with their hyperspectral sensor technology, which they are offering to the Navy as a new approach to anti-submarine warfare, search and rescue, mine countermeasure missions and homeland security.

STI is operating under contract to the Office of Naval Research, developing its "Littoral Airborne Sensor - Hyperspectral" for use aboard the P-3C Orion and SH-60 Seahawk as well as aboard airships, said Tom Glover, STI's director of programs for government systems. For the LASH airship program, STI has leased the Airship Management Services Skyship 600, a 200-foot blimp that has become a fixture in the skies around here since its first visit in late October. NAVAIR is providing program management for LASH.

At its most basic level, hyperspectral technology is "the science of color," said Greg Plumb, deputy program manager for the anti-submarine warfare portion of the LASH program. The optical sensor systems see color with a level of fidelity beyond anything the human eye-brain combination is capable of. Algorithms programmed into the system can be keyed to very specific colors, allowing operators to locate and track targets in situations where the human eye would never see them.

"We've set up three different tests around Pax River to show the wide diversity of hyperspectral technology," Plumb said. In nearby woods, STI technicians set up "enemy camps" under cover of the forest canopy. In the Bay, they tethered large discs under the surface to simulate anti-shipping mines. In another spot, they floated personal floatation devices such as might be worn by a victim in a search and rescue scenario.

Over repeated trials and demonstrations, the STI operators have shown the sensor's ability to ignore the extraneous colors of the forest canopy and the water, and key in on the colors of the targets. In much the same way, Glover said, the LASH system has been used to detect submarines at "tactically significant depths" in prior tests.

"This is the only optical ASW system that can do that," he said. LASH is entirely passive, emitting no energy to alert enemies that they are being surveilled.

While hyperspectral sensors have this advantage over radar-based sensor systems, they also have limitations. "We need sunlight, and we need line of sight," said Plumb. The system is also only as smart as the programmer makes it. The sensor requires a spectral library to make sense of the colors it is seeing and differentiate the needle from the haystack. Plumb said the library can contain color data for different camouflage schemes, submarine skins, mines, or even survival gear. Recent work has focused on reducing the false positive rate of the system, he added.

STI officials see LASH fitting in with an overall concept of operations in which different sensor types have different roles. On the ASW side, for instance, hyperspectrals are particularly suited to use in littoral areas, where acoustic systems must contend with reflections and noise disturbances, Plumb said.

Likewise, there may be areas where airships are superior sensor platforms to their heavier-than-air fixed wing and rotary wing counterparts.

"Airships are ideal surveillance platforms," said Steve Huett, who is NAVAIR's program manager for LASH Airship.

Chief among an airship's virtues is its ability to loiter. On a mission where helicopters could hover above a location for a couple hours, an airship might be able to spend a couple days, Huett said. Operating costs per flight hour run about a third as much as for heavier-than-air fixed wing aircraft, he added, due in part to much lower fuel consumption.

Airships are also extremely stable and produce relatively little noise or vibration, he said, providing ideal operating conditions for both sensors and their operators. Those same qualities make the blimp ideal as a science and technology platform, according to Plumb.

While the future of airships in the Navy is uncertain, Glover thinks that modern innovations will give the relatively old airship technology new life. Among the likely possibilities are automated flight controls to help the airship remain on station for long periods, and remote piloting.