The team, led by roboticist Guorui Li of Zhejiang University in Hangzhou, China, successfully field-tested the robot’s ability to swim at depths ranging from 70 meters to nearly 11,000 meters, it reports March 4 in Nature.
Challenger Deep is the lowest of the low, the deepest part of the Mariana Trench. It bottoms out at about 10,900 meters below sea level (SN: 12/11/12). The pressure from all that overlying water is about a thousand times the atmospheric pressure at sea level, translating to about 103 million pascals (or 15,000 pounds per square inch).
The tremendous pressures at these hadal depths — the deepest ocean zone, between 6,000 and 11,000 meters — present a tough engineering challenge, Gerringer says. Traditional deep-sea robots or manned submersibles are heavily reinforced with rigid metal frames so as not to crumple — but these vessels are bulky and cumbersome, and the risk of structural failure remains high.
Gerringer, one of the researchers who first described the deep-sea snailfish in 2014, constructed a 3-D printed soft robot version of it several years later to better understand how it swims. Her robot contained a synthesized version of the watery goo inside the fish’s body that most likely adds buoyancy and helps it swim more efficiently (SN: 1/3/18).
But devising a robot that can swim under extreme pressure to investigate the deep-sea environment is another matter. Autonomous exploration robots require electronics not only to power their movement, but also to perform various tasks, whether testing water chemistry, lighting up and filming the denizens of deep ocean trenches, or collecting samples to bring back to the surface. Under the squeeze of water pressure, these electronics can grind against one another.
This machine “pushes the boundaries of what can be achieved” with biologically inspired soft robots, write robotocists Cecilia Laschi of the National University of Singapore and Marcello Calisti of the University of Lincoln in England. The pair have a commentary on the research in the same issue of Nature. That said, the machine is still a long way from deployment, they note. It swims more slowly than other underwater robots, and doesn’t yet have the power to withstand powerful underwater currents. But it “lays the foundations” for future such robots to help answer lingering questions about these mysterious reaches of the ocean, they write
Deep-sea trenches are known to be teeming with microbial life, which happily feed on the bonanza of organic material — from algae to animal carcasses — that finds its way to the bottom of the sea. That microbial activity hints that the trenches may play a significant role in Earth’s carbon cycle, which is in turned linked to the planet’s regulation of its climate.The discovery of microplastics in Challenger Deep is also incontrovertible evidence that even the bottom of the ocean isn’t really that far away, Gerringer says (SN: 11/20/20). “We’re impacting these deep-water systems before we’ve even found out what’s down there. We have a responsibility to help connect these seemingly otherworldly systems, which are really part of our planet.”

Source: https://www.sciencenews.org/article/new-soft-robot-snailfish-crushing-pressures-deep-ocean