The rover’s entry, descent and landing (EDL) microphone also captured “bangs, pings and rattles” made by Perseverance’s six metal wheels and suspension on its first test drive two weeks ago, though Nasa’s Jet Propulsion Laboratory only published them on Wednesday.
“If I heard these sounds driving my car, I’d pull over and call for a tow,” said Dave Gruel, a senior Nasa engineer on the rover team “But if you take a minute to consider what you’re hearing and where it was recorded, it makes perfect sense.”
Perseverance – the biggest, most advanced rover ever sent to Mars – landed near an ancient river delta on 18 February to search for signs of past life. Samples will be taken from the most promising rocks for eventual return to Earth.
The rover carries two microphones. One already has captured the sounds of wind and rock-zapping lasers, the other was meant to record the descent and landing. This second microphone didn’t pick up any sounds of the rover’s arrival at Mars, but managed to record the first test drive on 4 March.
“A lot of people, when they see the images, don’t appreciate that the wheels are metal,” said Vandi Verma, a senior engineer and rover driver at Nasa’s Jet Propulsion Laboratory in Southern California. “When you’re driving with these wheels on rocks, it’s actually very noisy.”
The driving audio of the unexpected scratching noise remains a mystery to Nasa, with engineers currently trying to figure it out.
“Perseverance’s engineering team continues to evaluate the source of the scratching noise, which may either be electromagnetic interference from one of the rover’s electronics boxes or interactions between the rover mobility system and the Martian surface,” Nasa said in a statement.
The rover is also currently searching for a suitable airfield for its Mars Helicopter to attempt its first flight
Before it starts drilling into rocks for core samples, Perseverance will drop off the experimental tag-along helicopter, named Ingenuity. If its flight is successful, it will be the first ever powered, controlled flight on another planet.
Ingenuity will then have up to 30 Martian days (31 Earth days) to complete up to five test flights on the red planet.
Additional reporting from agencies.