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ABL uses balloons to gather turbulence data

Released: 29 Feb 2000


by Staff Sgt. Cindy York
Air Force Print News

OSAN AIR BASE, Republic of Korea -- It sounds like something a child would love to do. Staying up all night, building something out of foam, cardboard and wires, powering it with batteries and then a ttaching it to a huge balloon. The most exciting part of the night, however, is letting the 6-foot-wide balloon go into the air, willing it to make it past electric lines so as not to knock the power out ... again.

Actually, this job is no small task and the implications from doing it wrong could be costly. Balloons launched here and from Doha, Qatar, provide vital information for the Airborne Laser Program.

Working hand-in-hand with specialists from the 452nd Flight Test Squadron at Edwards Air Force Base, Calif., the Air Force Research Laboratory at Kirtland AFB, N.M., and the 452nd's Detachment 2 at Kirtland, three specialists from Hanscom AFB, Mass., are gathering information to help understand atmospheric turbulence -- an initial nemesis of the ABL.

After several years of sending balloons in to the air from here and Doha, Lt. Col. John Roadcap, technical advisor in the tactical environment support branch at the AFRL at Hanscom, along with Air Force contractors Kris Robinson and George Clement, have their craft down to an art.

It takes only a short time to get their three "payloads" ready each night. Four pounds of foam, plastic, wire and batteries are attached to the end of a 330-foot-long nylon line, which is then attached to a large balloon. Inside the payload is the equipment to transmit current levels of temperature, air pressure and humidity, and very small temperature differences measured across the length of the package.

As the balloon rises at a rate of about 16 feet per second, it sends this information to the ground station, which records these atmoshperic conditions. This information, along with the star optical measurements collected from the aircraft, is used to determine the optical turbulence in the atmosphere.

The balloons are launched at the same time the C-135E Argus is in the air gathering atmospheric turbulence data at about 45,000 feet. It's important the two sets of data be collected concurrently so the data is interpreted with the same atmospheric conditions, according to Roadcap. If the balloons run into power lines or otherwise don't collect their data, the information recorded during the Argus flight might not be as useful.

"Without the vertical data the balloons collect, it will be difficult to interpret the star measurements," Roadcap said. "We need to understand why, when we're looking at the stars from certain elevation angles, that the atmospheric turbulence values are increasing or decreasing."

Roadcap said collecting data from the balloons is crucial to the ABL program.

"This is very important," Roadcap said. "We need to know everything we can about the atmosphere and its possible effects on the laser because this is the way of the future."

The results from the testing will help with the employment of the airborne laser, a key player in the nation's theater missile defense strategy. When fully operational in 2008, the ABL will be the primary weapon used to attack theater ballistic missiles during their boost phase. It will destroy them early in flight before their warheads have an opportunity to separate from the boost vehicle. With this strategy, the warheads and destroyed missile components will fall back on enemy territory, exposing them to whatever warhead they employed.

RELATED SITES

* Airborne Laser Program
* Osan Air Base
* Edwards Air Force Base