Some of the greatest discoveries in science are the result of years of hard work, diligence, and an almost constant stream of testing and retesting. But sometimes, even the greatest scientific minds of our generation still find beneficial results from their experiments entirely by accident!
Take NASA for instance—typically, we think of the iconic space agency as discovering new ways to send astronauts into outer space and (more importantly!) bring them home to Earth. But recently, NASA scientists applied the same engineering skills they use to build rockets to skyscrapers in major cities—and the results are surprisingly cool!
In 2013, NASA was working on one particular rocket that was known for violently shaking during launch. Testing revealed that the Ares rocket, a crew launch vehicle, would shake so hard during ascent that it could harm astronauts on board. So one NASA team experimented with controlling the heaviest part of the rocket—its fuel. That got the team thinking: If this technique worked on a rocket, why not a building?
To understand this concept a little better, it might be helpful to know that the normal approach to counteracting vibrations is to add more weight to an object. According to Quartz, hundreds of buildings around the world use a system called a tuned mass damper (TMD). A very heavy device, called a secondary mass, is attached to a building to counteract its movements, sort of like a counterweight in a grandfather clock.These systems respond to movements by shifting in the opposite direction. So if an earthquake or high winds force a skyscraper to sway to the right, the TMD responds by swaying to the left—counteracting the motion.
In the case of the 650,000-pound Ares rocket, a TMD system wasn’t practical. Adding more weight would have made it impossible to get the rocket off the ground. Rob Berry, the NASA project manager working on the Ares rocket, and his team had to get creative.
They realized that making the rocket’s fuel move in a way that counteracted the vibration would perform the same function as adding more weight. So they identified the frequency of the rocket’s vibration—then changed the liquid’s frequency to match it. Their final product is called the LOX Damper, a vibration controlling mechanism that doesn’t add any weight to the system. It reduced the vibration of the rocket so it could safely transport astronauts into outer space again. The same concept can be applied to buildings, Berry explains.
“Everything with mass and stiffness has got a natural frequency, (so) a building will want to move,” he says. “Say the building wants to move at 2.5 hertz. They’ll set that to be the frequency of the tuned mass damper. That knocks out some of the response of the building.”
To test out the technology, the NASA team developed a new device called a disruptive tuned mass (DTM) specifically designed for buildings. The latest version of the device is approximately the size of coffee can. It can be placed in a building’s swimming pool, pipes, or even a sprinkler system. After an engineer determines the frequency at which a building naturally begins to move in the event of an earthquake or high wind, the DTM is set to match that frequency.
Now normally, this device would protect against high winds that can sometimes shake very tall buildings on a windy day. But if the building owners decide they want the structure to be even more stable and withstand, say, an earthquake, they can adjust the frequency to which the DTM is set. This technology also means that buildings will be able resist movement from the instant an earthquake strikes.
Still, there’s no way to ward off earthquakes entirely. But it’s clear that we can do more to protect buildings from the shifting of tectonic plates beneath the Earth’s crust. Thanks to NASA, engineers now have one more good option. It just goes to show you what a little creative engineering can do to make a real difference in the world!
Photo credit: NASA