Space is louder than one might think. Crewed spacecraft, whether that be a transportation vehicle or a station module, are made noisy by life support systems, electronic fans, radios and crew activity. NASA has long been concerned about the effects of this acoustic environment on its astronauts, and the agency has introduced a number of modifications over the years to make the International Space Station a quieter place.
But there’s still plenty of room for improvement. Whisper Aero, a Tennessee-based startup best known for its ultra-quiet electric propulsor for aircraft, drones and even leaf blowers, scored a new NASA contract to design the quietest possible fan that’s suitable for crewed space environments. At the end of the six-month effort, the startup is aiming to have prototype parts to show to NASA; if the agency deems this Phase 1 project successful, Whisper would likely move on to test a design prototype next year.
In Phase 2, NASA and Whisper would compare the acoustic and aerodynamic estimates from this Phase 1 small business and innovation research (SBIR) contract with the measurements of its fan and a baseline NASA Spacecraft Cabin Ventilation Fan.
“Unless you’re using significantly different technology, you’re going to end up with the same kind of noise challenges and efficiency challenges in space in the crewed quarters as you would on Earth,” Whisper COO Ian Villa explained in a recent interview.
According to one recent paper, noise exposure levels in the crewed portions of the International Space Station were around 73 decibels (dB) on average. NASA has developed a space fan that achieves 66 dB at two feet; Whisper is aiming to meet or exceed 61 dB at two feet while also being 75% more efficient. That means lighter and smaller, without the silencers that take up weight and space. (For reference, Whisper says a noisy washing machine or vacuum cleaner is between 70 and 80 dB, while normal conversations are around 30 to 60 dB.)
The company is using a lot of the core technologies that it has developed for its terrestrial applications, like its shrouded fan that’s able to move the fan’s blade passage frequency up into the ultrasonic and minimize the remaining tones. But the space environment presents some new challenges. The propulsor has to operate continuously, for a matter of years; the motors running the fans may run for longer than a fan in, say, a leaf blower.
No doubt acoustic environment planning is also on the minds of the suite of private space station developers that are looking to send up replacements for the ISS when it is decommissioned by the end of the decade. Villa wouldn’t comment on whether Whisper is having conversations with any of these companies, but “it’s definitely a challenge for them,” he said.
“It still remains to be seen exactly how we commercialize, but I think the mission of just being able to deliver cleaner, quieter, more efficient air delivery, that’s what we want, if that’s in space, or if it’s on Earth.”
The sensitivity of noise — both noise level and noise quality — could be even more important as private stations start to fly luxury space tourism customers, rather than solely professional astronauts. Companies may want to maximize how pleasing the environment is versus their competitors.
NASA even has an interest in quieter fans for space suits, though Villa said how the company would integrate the fan into a spacesuit is to be determined.
Noise is “a challenge that often is forgotten until it’s too late, and then you can’t change it,” Villa said. “You can’t fix it. We’ve seen this time and time again on aircraft. It’s almost refreshing to see this in spacecraft, in that they’re actually trying to do something about it at NASA.”
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