CAPE CANAVERAL, Fla.—First came the amazing pictures, then the video. Now NASA is sharing sounds of its little helicopter humming through the thin Martian air. NASA’s Jet Propulsion Laboratory in California released this first-ever audio Friday, just before Ingenuity was set to soar on its fifth test flight. The low hum from the helicopter blades spinning at more than 2,500 revolutions per minute is barely audible. It almost sounds like a low-pitched, far-away mosquito or other flying insect. That’s because the 4-pound (1.8-kilogram) helicopter was more than 260 feet (80 meters) from the microphone on the Perseverance rover. The rumbling wind gusts also obscured the chopper’s sound. Scientists isolated the sound of the whirring blades and magnified it, making it easier to hear. The sound was recorded during the helicopter’s fourth test flight on April 30. Ingenuity—the first powered aircraft to fly at another planet—arrived at Mars on Feb. 18, …