NASA “makes the invisible visible” by taking incredible photograph of U.S. civilian jet breaking the sound barrier

An image released on Monday has captured the moment a civilian jet broke the sound barrier during a historic test flight over the Mojave Desert.

The photograph, supplied by NASA and Boom Supersonic, captured the moment the XB-1 aircraft – “the first supersonic jet made in America” – broke the sound barrier using a technique known as Schlieren photography to visualize what can’t be seen with the naked eye.

“This image makes the invisible visible," Boom Supersonic founder and CEO Blake Scholl said in a news release.

Scholl added that the aircraft didn’t make an audible sonic boom that usually happens when an aircraft is flying faster than the speed of sound. The data collected suggests that at a certain speed and in specific atmospheric conditions, the sonic boom refracts in the atmosphere and never reaches the ground. This finding might lead the way for supersonic commercial flights without sonic booms, the company said in the news release.

Schlieren photography is similar to the shadowgraph technique and relies on the fact that light rays are bent whenever they encounter changes in density or fluid.

“Schlieren systems are used to visualize the flow away from the surface of an object,” says NASA, “A mercury vapor lamp or a spark gap system is used as a bright source of light. The light is passed through a slit which is placed such that the reflected light from the mirror forms parallel rays that pass through the test section. On the other side of the tunnel, the parallel rays are collected by another mirror and focused to a point at the knife edge. The rays continue on to a recording device like a video camera.”

The photo was taken during the XB-1’s 13th overall test flight, according to the company. It was the second time it flew at supersonic speed, this time reaching Mach 1.18, or 722 mph, Boom Supersonic said.

Chief test pilot Tristan "Geppetto" Brandenburg had to position XB-1 in exactly the right location at the right time to allow NASA's team on the ground to photograph it in-flight as it eclipsed the sun, the Colorado-based company said. The crews used telescopes with special filters that can detect air distortions – like shock waves – to capture the image.

“Knowing where the air is really moving tells you a lot about what your vehicle is doing, how efficient it is, and how you can make it better," Ed Haering, principal investigator for the Schlieren photography, said in a 2023 NASA news release.

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