Why in news?
• Recently, NASA has captured first-ever photos of two supersonic shock waves (pressure waves) colliding with each other in the air.
About Shock waves
• When an airplane travels less than the speed of sound, the air ahead of it actually begins to flow out of the way before the plane reaches it. The pressure waves created by the airplane passing through the air end up being smooth and gradual.
• But as an airplane reaches the speed of sound and catches up to its own pressure waves, the air ahead of it receives no warning of the plane’s approach. The airplane plows through the air, creating a shock wave.
• As air flows through the shock wave, its pressure, density, and temperature all increase—sharply and abruptly.
• Shock waves produced by aircraft merge together as they travel through the atmosphere and are responsible for what is heard on the ground as a sonic boom.
• The NASA has captured flow of the interaction of the shock waves from two aircraft for the first time.
• The flight series saw successful testing of an upgraded imaging system capable of capturing high-quality images of shock waves, rapid pressure changes which are produced when an aircraft flies faster than the speed of sound, or supersonic.
• Objective: It is a part of its efforts to develop planes that can fly faster than the speed of sound without producing thunderous sonic boom.
• The system will be used to capture data crucial for the design of the supersonic plane, which will produce shock waves in such a way that, instead of a loud sonic boom, only a quiet rumble may be heard.
• The ability to fly supersonic without a sonic boom may result in lifting current restrictions on supersonic flight over land (which presently prohibits anyone from operating a civil aircraft at supersonic speed in the United States and from a certain distance off shore where a boom could reach U.S. shores.)