Space is far from silent on the International Space Station. The fans, pumps, and valves create such a din that NASA has a new worry— permanent hearing loss.
"The equipment really vibrates the structure, creating a drumlike effect," says Jerry Goodman, head acoustical engineer on the space station. His team has helped design mufflers for the Canadian-built robot arm and damping systems for Russian airlock pumps. Now they are working to quiet the Japanese centrifuge and the Russian cargo module, which is so loud the crew has to wear earplugs.