The device is a hollow truncated cube with its corners cut off and replaced by triangular surfaces. The 6.5-inch cube is filled with about 90% water and 10% air. Eight small, motorized propellers on the inside of each triangular corner mixes the air and water inside evenly, creating a highly controlled bubble factory (or homogeneous isotropic turbulence chamber, to be precise). It’s also festooned with cameras, microphones and other sensors to take precise measurements of the dynamics inside. 

To simulate zero gravity, Federle used a NASA drop tower — an eight-story shaft that provided her device about 2 seconds of simulated weightlessness before landing on an airbag at the bottom. The bag softens the blow at the bottom considerably, but Federle’s device still had to hold up to extreme forces. To build it, she worked with Ben Lyons, a technical assistant in the Brown Design Workshop, to fabricate components, weld the frame and assemble the final device. 

“It was terrifying to drop our experiment that I worked on for many months,” Federle said. “But everything went flawlessly for the most part. We were able to drop our experiment 15 times within two days of testing, and we got great data.”

However, two seconds of weightlessness is not a lot. Longer periods would make for richer data. So with the help of the NASA Rhode Island Space Grant Consortium, which is based at Brown, Federle managed to get a spot on a reduced gravity aircraft flight, the “vomit comet,” as it’s affectionately known. The aircraft flies a parabolic trajectory — up and down through a roller-coaster-like series of peaks and troughs. Each peak in the flightpath provides about 20 seconds of weightlessness.

Not only did the flights provide longer periods of weightlessness, but Federle was able to travel with the experiment and watch it as it happened. 

“It was absolutely awesome being in weightlessness,” Federle said. “But it was doubly awesome to be there and see what was happening. For one thing, the bubbles were way bigger in microgravity than we expected them to be, and they broke up very differently. We could see that in real time, which was great.”

Her device once again performed well, and she has several terabytes of data from her flight that she’s now poring over, hoping for some new insights into bubble behavior. She and her adviser, Professor of Engineering Roberto Zenit, hope to submit a series of research papers on the work in the coming months. 

But Federle’s interest in weightlessness is more than just academic. 

“My dream is to be an astronaut,” she said. “So a parabolic flight was definitely something I wanted to experience, and it was awesome and epic that I was able to achieve that. The experience was one of the best days of my life.”

Federle says she’s profoundly grateful to Brown and the School of Engineering for providing her with the freedom and encouragement to pursue this line of research. 

“Brown has provided me the environment to do this and be who I want to be,” Federle said. “I don’t think many other universities and or advisers would allow this to happen. I’m utterly grateful for the support from the Rhode Island Space Grant Consortium, because if it wasn’t for them, we wouldn’t have been able to do all this.”