If you were driving your car down the highway at 80 miles per hour and it started to make a bizarre whirring noise you’d never heard before, you’d know something bad was going on. The same principle applies when you’re sitting inside a hunk of metal orbiting Earth at 17,150 mph, 254 miles above the surface—namely, the International Space Station. Things will clank and buzz and screech in a disconcerting way when the space station isn’t doing so well.
But many potentially dangerous sounds can’t be picked up by human ears. Take, for instance, the leak on the space station found last year. A two-millimeter hole went unnoticed for nearly a day before it was found and patched; while it posed no immediate danger to the crew, not all leaks are equally nonthreatening. Luckily, they make a noise at ultrasonic frequencies. If you have a tool that can measure these tones, you could be alerted to any leaks when they come up.
“Sound, by itself, tells a lot of stories about the environment,” says Samarjit Das, a researcher at the North American branch of the multinational company Bosch. We’re already seeing how smart speakers are using AI to better recognize speech and make sense of acoustic patterns they recognize in their environment. When these techniques are applied to machines, “we can learn a few things about machine health we would otherwise have missed completely,” he says.
To shore up our hearing in space, NASA has partnered with Bosch to send an acoustic monitoring system called SoundSee up to the ISS on November 2 during Northrop Grumman’s Cygnus NG-12 mission. SoundSee is an array of delicate microphones capable of listening in at frequencies ranging from less than 100 hertz all the way up 80 kilohertz (the range of human hearing is between 20 Hz and 20 kHz) and then analyzing the data using a mix of different kinds of software, including deep-learning AI. The system will be attached to an autonomous Astrobee robot that flies around the station and assists astronauts in their tasks throughout the day. The hope is that it will map the acoustic environment of the entire station and be able to alert astronauts to any unusual sounds.
Besides leaks, the agency hopes to use SoundSee to autonomously spot and seek out peculiar patterns or anomalies related to oxygen generation and circulation, water recovery, air temperature and pressure control, and even exercise equipment.
It’s not easy to design an acoustics system for space. Astrobees are tiny cube-shaped robots propelled autonomously through the station with electric fans. They’re built small so they can move around easily in the confined space of the ISS, so the SoundSee module had to be small too. That’s a challenge for measuring sound, says Bosch research scientist Jonathan Macoskey. Low frequencies are easier to listen to via a recording device with a wide design, while it’s easier to detect high frequencies using narrower designs. The Bosch team had to come up with something that could do both.
SoundSee will be hitching a ride on Astrobee for at least a year. According to Das, the project lead for SoundSee, NASA and Bosch are already thinking about the importance of acoustic monitoring systems for future space stations like Gateway, which is meant to orbit the moon with astronauts on board and eventually help get people to Mars. Gateway will be uncrewed for extended periods of time. In the absence of a human presence, it’s critical to have proper sensors that can make sure the station remains safe for any astronauts who will visit.
Das hopes SoundSee will have an impact on acoustic systems on Earth, too. “You can imagine a ground-based robot running around and acoustically monitoring major infrastructure here on Earth in the same way,” he says. As we increasingly move toward automated systems to run our critical infrastructure, acoustic monitoring might help prevent small problems from blowing up into big ones.