Labs sky scanner can detect a cloud of germs from three miles away

Someday soon the skies over US cities or upwind of major sporting events might be scanned for airborne biological agents using a device now under development at Sandia.

Named "Ares" after the Greek god of war, the telescopic scanner is mounted just inside the rear doors of a large passenger van.

The mobile biological weapons standoff detection system, as it’s called, can be taken anywhere the concern exists that terrorists might release biological weapons agents into the air, such as anthrax, smallpox, tularemia, plague, botulinum toxin, or other bugs.

Once the van is stabilized and its rear doors opened, an ultraviolet pulsed laser mounted on a gimbal whips across a 90-degree wedge of sky once every 20 to 30 seconds, sending out 600 to 1,000 laser pulses on each pass.

A telescope and detector wired to a computerized location system follows the beam, watching for bright spots that could indicate the presence of smoke, diesel fumes, dust clouds, or something more sinister.

Bright spots

The beam more or less uniformly illuminates the floating dust and other contaminants normally present in the lower atmosphere, explains Ares developer Phil Hargis (1118). Where contaminants are concentrated in a plume, more UV light is reflected, he says.

If a cloud of aerosol particles is detected, he says, the system quickly maps its boundaries using time-of-flight information associated with the UV pulses and positional information from the gimbal and determines the location of the most concentrated portion of the cloud.

It then probes that portion of the cloud looking for the presence of biological materials.

Because biological materials naturally fluoresce, or shift the color of light they reflect when exposed to UV light, the Ares system can tell whether a cloud contains biological aerosols by looking for very specific wavelengths, or colors, of fluorescent light in the UV-illuminated cloud.

The detection, mapping, and analysis takes approximately 10 seconds.

Detect to warn

"This is a ‘detect to warn’ system," says proj-ect manager Al Lang (5713). "It can’t identify the particular bug, but it can tell you that a cloud has bio-content so you can take protective action."

The Ares prototype system works best out to about three miles, he says.

Currently no standoff detection capability exists either on the battlefield or in the homeland security community, he adds.

The Department of Defense is evaluating the capabilities of several developmental systems, including Ares, during a series of field tests this month at Dugway Proving Ground in Utah.

Dugway specializes in creating plumes of airborne particulates and biological simulants with well-characterized optical signatures.

The detection hardware also could be mounted on the rooftop of a building for more permanent applications, says Al.

Noisy environments

The Sandia prototype device, built from commercially available components to keep costs down, seems rather straightforward on its surface, Al says.

But the technical challenge lies in discriminating between the normal airborne contaminants, such as plumes of diesel exhaust and pollens, from deadly biological particulates, and doing so with very few false alarms.

"It’s straightforward in a scientific sense, but it is a whole lot more difficult to get it to work reliably in environments where you’d expect a lot of noise, including urban and battlefield environments," he says.

The Sandia team has been field-testing the system night and day with a variety of simulants, including floating flour and dust, in the sky over a remote area near Sandia’s 10,000-foot sled track in Area 3.

The Dugway test series, which began Monday, is evaluating each system’s ability to detect and discriminate among several types and concentrations of contaminant plumes, he says.

The Ares system is expected to meet the DoD’s operational requirements, he says.

Negotiations are underway with a private company to develop a cooperative research and development agreement that would result in the Ares technology being commercialized for both the military and homeland security sectors.

Sandia has been working on the basic technology for the Ares system since about 1993, says Al. But it wasn’t until 9/11 and the anthrax letter mailings in fall 2001 that the National Nuclear Security Administration asked the Sandia team to focus on biological standoff detection for homeland security applications.

The project is funded by the NNSA’s Office of Nonproliferation Research and Engineering.

Sandians from both the New Mexico and California sites have supported the Ares project. The following centers have been directly involved: 1100, 2300, 5700, 6100, 8100, 8300, 8400, and 8900.