NASA Microphone Can Pick up Turbulence More Than 300 Miles Away

Those who have used air travel at one point in their lives know how terrible it can be to get caught in the middle of turbulence. These "horizontal tornadoes" can possibly make you tightly grip your seat while your life flashes before your eyes -- the flight experience with them can be rather uncomfortable and possibly dangerous.

Attempting to avoid them can consume large amounts of fuel, but NASA researchers have developed a novel technology that can find these zones with ease by keeping a close ear on infrasound, which consists of pitches too low to be heard by the human ear, between 0.001 and 20 hertz, according to a report by the space agency.

The clear-air turbulence, which can occur without a warning and can't be easily detected visually, has a specific infrasound which researchers Qamar Shams and Allan Zuckerwar at NASA’s Langley Research Center in Hampton, Virginia, realized that can be detected before airplanes encounter them. This way, air traffic controllers or pilots could plot an alternate route to bypass them. 

However, in order to do that, they needed a special microphone first. When they found that the sensors didn't perform well, Shams says, "We thought, 'We have combined expertise in instrumentation, so why don’t we design a microphone ourselves?'"

Detecting and forecasting turbulence

The duo started developing a microphone that could pick up the ultralow frequencies generated by turbulence in the skies. They used a low-tension diaphragm with a wide radius paired with a large, sealed air chamber behind it to allow it to detect these sound waves at great distances. Once the sensor was done, they began testing by placing the microphones in an equidistant triangular pattern around Langley’s runway. This enabled them to pick up and locate atmospheric turbulence more than 300 miles (483 kilometers) away.

Stratodynamics, which is a company that provides high-altitude flight services for global clients, licensed the patents from NASA and implemented the sensor on an uncrewed stratospheric glider, the HiDRON.

The initial tests showed that the microphone did a great job. It was able to separate the low frequencies from the ambient conditions successfully. Further testing of the algorithms will be conducted to understand the turbulent signature's intensity and range.

“As infrasonic detection continues to prove its value as a turbulence mitigation technology, its potential to forever alter the landscape of aviation grows stronger with every flight," stated Nick Craine, business development lead at Stratodynamics.

The researchers hope that the special microphone will become universally used in detecting and forecasting turbulence, thus ensuring safer and more comfortable flights as well as making sure less fuel is wasted.