The astronauts can watch, too, through a computer display that lets them watch the results of their won activities. Mission scientist Pete Curreri said the display, first used on USMP-3, quickly led to a quieter mission when the crew could see their own movements displayed as SAMS data. From that, they figured out how to adjust their activities to minimize their impact, literally, on the mission. Scientists call it microgravity because anything aboard a spacecraft experiences a tiny bit of acceleration. That would be okay, except that the spacecraft itself vibrates.
Motors pump fluids and run fans, valves open and close, antennas point and repoint, and so on.
In everyday life, we ignore the refrigerator or air conditioner switching on and off. But for microgravity scientists, even properly functioning equipment can be like an unbalanced washing machine rattling the house. That's where SAMS comes in. With sensors deployed around the Shuttle, SAMS measures the intensity of vibrations at different frequencies. The movement is sensed and an electromagnet adjusts to push the pendulum back into place.