Anna Du was walking along Castle Island’s beach in South Boston when she noticed plastic scattered on the shoreline. She reached down to pick it up, and quickly realized there was many more tiny pieces than she could handle.
“When I realized how many pieces there were, it seemed impossible,” says Du, who was in sixth grade at the time.
But Du approached the problem like any good scientist—first, by doing a little research. That’s how she learned that 8 million metric tons of plastic end up in the oceans every year—and that’s in addition to the whopping 150 million metric tons that are already there.
Du’s ROV is made with PVC pipes. Inspired by ROVs of all sorts, like the Curiosity lander that spies on the surface of Mars and the deep sea arctic Nereid ROV at Woods Hole Oceanographic Institution (WHOI), Du’s ROV has two separate systems, a navigation system and a detection system. The navigation system is pretty simple: it uses propellers to move through the water and a novel combination of fishing weights and foam pool floats that allow it to move up and down.
When Du first read about the challenge of locating ocean microplastics that, unlike the Great Pacific Garbage Patch, are not floating on the surface, she knew that an ROV would be the most efficient tool for the task. Taking buckets and buckets of water samples and analyzing them in a lab could never be done to the scale needed. She needed a mobile lab that could find the plastics in-situ.
Du has been attending public events and workshops at MIT since she was five years old, and so she picked up the engineering skills necessary to build her ROV from these sessions, maker labs at local libraries and YouTube. She says actually getting her device to move through water well was tricky—even down to choosing the right kind of glue to use to hold the PVC pipes together. Before she added fishing weights, for example, the ROV would flip over when she tried to move it up and down. There was a lot of trial and error as she tested her ROV in Boston Harbor.