Use wechat scan QR code < / P > < p > to share with friends and circle of friends < / P > < p > <-- On Friday, May 8, local time, NASA released the "a target ="_ blank" href=" https://news.163.com/news/search?keyword=%E7%81%AB%E6%98%9F "> Mars < / a > vehicle" perseverance "sent back the latest documents, including Mars < a target ="_ blank" href=" https://news.163.com/news/search?keyword=%E7%9B%B4%E5%8D%87%E6%9C%BA "> helicopter < / a >" smart "conducted its fourth mission on Mars < a target ="_ blank" href=" https://news.163.com/news/search?keyword=%E9%A3%9E%E8%A1%8C "> the sound of flying < / a >. This is the first time in human history that a probe has recorded the sound of another spacecraft on the surface of an alien world On April 30, 2021, the fourth Mars test flight was carried out by the smart, and the microphone attached to the supercam instrument on the willpower Mars rover captured the hum and wind from the helicopter rotor. At that time, the rocks were irradiated by lasers from a distance, and their vapors were studied by spectrometers to reveal their chemical composition. The instrument's microphone records the sound of the laser strike, which provides information about the physical properties of the targets, such as their relative hardness. The microphone can also record ambient noise, such as the wind from Mars < p > David mimoun, Professor of planetary science at the French National Institute of Aeronautics and Astronautics and head of microphone science at supercam, said: "it's a big surprise. Our tests and simulations on earth show that the microphone can hardly hear the sound of the helicopter, because the Martian atmosphere strongly suppresses the sound propagation. However, we are very lucky to record the sound so far away, and it will become a gold mine for us to understand the Martian atmosphere. " There are two microphones on board, one is the supercam instrument microphone, the other is the Mars rover entering the Martian atmosphere, descending and < a target = "_ blank" href=" https://news.163.com/news/search?keyword=%E7%9D%80%E9%99%86 "> landing < / a > microphone as part of the camera system. The two microphones captured sounds from Mars before April 30, the first time they have recorded on the surface of Mars However, the mission team did not try to record the audio until the fourth test flight of the smart. They are not sure if the microphone can capture any flying sound. Even in flight, when the helicopter's rotor rotates at 2537 rpm, the sound will be greatly weakened by Mars's thin atmosphere. At the beginning of the flight, the gust on Mars will also cover it. Listen carefully, though, and the hum of the helicopter's rotors is faintly audible in the Martian wind < p > by isolating the 84 Hz helicopter rotor sound, the scientists reduced the frequency to below 80 Hz and above 90 Hz, and increased the volume of the remaining signals, making the audio recorded in mono easier to be heard. Some frequencies have been cut to highlight the drone of the helicopter. When the helicopter passes through the field of view of the camera, the buzz is the biggest "This is an example of how different payload instrument packages complement each other and produce information synergy," said Soren Madsen, payload Development Manager for NASA's Jet Propulsion Laboratory. In this particular case, the microphone and video allow us to observe the helicopter as we are in the field, while the additional information generated by other instruments can confirm the details of the flight path. " < p > supercam was developed by Los Alamos National Laboratory in New Mexico, including several spectrometers, control electronics and software. The mast, including the microphone, was developed and built by CNRS, the National Institute of Aeronautics and Astronautics and several laboratories of the University of France. The calibration target system on the deck of the Mars rover is provided by the University of baladolide in Spain On February 18, wit and willpower Rover landed in the yezelo crater. Billions of years ago, it was a huge lake and River Delta. In early April, witty began the first demonstration of human flight technology on an alien planet. Nasa decided to extend its mission because of its excellent performance. The helicopter is now transiting to a new stage, during which it will try to demonstrate the reconnaissance potential of Mars rotorcraft The fifth flight test is about to be carried out, which is different from the previous four round-trip flights. This flight is a one-way flight, and it will fly to the new airport 129 meters away from its current position. The new site is on the route of the willpower project, and the two must be kept relatively close, because the communication of the wit must be completed through the willpower. At the same time, willpower is preparing for its own scientific mission, which has two main objectives: to find signs of ancient life on Mars, and to collect and store dozens of samples for future return to earth < p > JPL < span style = "background color: rgb (255, 255, 4);" > " Smart number < / span > < span style = "background color: rgb (255, 255, 4);" > " < p > <-- EndFragment-->