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Woods Hole, Mass. (Dec. 10, 2024) – Recent missions by underwater vehicles operated by the Woods Hole Oceanographic Institution (WHOI) highlight the diverse locations and science questions that the Institution’s engineers and technology routinely support.
Nereid Under Ice (NUI) in Greenland
The hybrid remotely operated vehicle (HROV) Nereid Under Ice (NUI) spent much of late summer giving scientists from the University of Texas at Austin a close-up look at the foot of actively calving glaciers on the southwest coast of Greenland. The project, supported by the W.M. Keck Foundation, aimed to improve understanding of the processes that affect ice melt and, as a result, global sea level.
NUI’s ability to operate far from its support ship allowed WHOI engineers to remain at a safe distance aboard the research vessel R/V Celtic Explorer while driving the vehicle as close as 50 meters (150 feet) from meltwater channels at the base of the glacier to collect seafloor samples and make measurements never before possible.
WHOI engineers remotely piloted the vehicle along the 5 kilometer (3 mile) long, 300 meter (980 foot) tall underwater face of a glacier, flew in and out of huge caves at the foot of the glacier, and maneuvered under roiling meltwater plumes raining down sand on the vehicle. As Victor Naklicki, NUI pilot and an engineer with WHOI’s Applied Ocean Physics & Engineering Department (AOPE) explained, “Putting a remotely operated sub under anything means it can’t float back to the surface if something goes wrong. But the prize is collecting data we’ve never had before.”
The team also collected core samples of sediment piling up at the foot of a glacier–something that had never been accomplished. The data from NUI is critical to solving the mystery of how sediment banks influence glacial processes like melting and calving.
“This is what NUI was designed for,” said Molly Curran, NUI Expedition Leader and research engineer, AOPE at WHOI. “The vehicle and team performed really well and showed what’s possible.”
“It was a high risk, challenging environment,” she continued. “The unique capabilities of the vehicle allowed us to reach horizontal distances of over 5km from the ship while still having full communication back to the ship through the tether.”
“NUI provided an unprecedented view of the terminus of a glacier,” said expedition chief scientist Ginny Catania, a professor at UT Jackson School of Geosciences and the University of Texas Institute for Geophysics. “Not only were we able to get in close to the terminus to see features that we’ve never seen before, but the quality of NUI data enabled us to quantify these features in a way that has never occurred before.”
“NUI was originally designed for work under both sea ice and glaciers. Sea ice presents its own challenges, but working at the face of a massive, actively calving glacier was new for the vehicle and for the team,” said Mike Jakuba, senior engineer at WHOI, NUI vehicle manager, and technical lead on the mission.
Mesobot and Sentry in American Samoa
At the same time as NUI was working in Greenland, the autonomous underwater vehicle (AUV)Mesobot was making its own discoveries in the equatorial Pacific from the exploration vessel E/V Nautilus as part of a mission funded by the Ocean Exploration Cooperative Institute (OECI) and including scientists from WHOI, the Ocean Exploration Trust, the University of Rhode Island, Lehigh University, and the University of New Hampshire. Mesobot and its team of engineers were part of a group studying the importance of the underwater volcano Vailulu’u in supporting water column biodiversity, including fish and whales, east of American Samoa.
During the expedition, Mesobot made dives to explore the midwater region of the ocean known as the twilight zone to help better understand the link between it and surface waters where people from nearby islands have fished for generations. All totaled Mesobot made 16 dives, four into the crater of Vailulu’u–the first time it ever entered an active underwater volcano and caldera, which is the depression formed when a volcano erupts and collapses.
“We designed Mesobot to operate in the midwater far from the seafloor, so we were a bit anxious about launching it into the caldera,” said Dana Yoerger, senior scientist at WHOI, and Mesobot developer. “By planning the dives carefully, we were able to send Mesobot deep into the caldera on four dives.”
On the mission, Mesobot tested some of its new upgrades, including improved camera lighting and an optical lure to attract midwater organisms. The cameras, along with eDNA samplers, helped to characterize the deep scattering layer, and extend scientists’ understanding of the link between life in the midwaters and hydrothermal vent activity on the seafloor.
“The eDNA samples obtained from Mesobot from in and above the caldera are invaluable for us to connect the microbial production associated with the venting–located far below the sunlit layer where photosynthesis occurs–and the diversity of animals in the overlying water column,” said Annette Govindarajan, WHOI biologist and science lead for the cruise.
The second leg of the OECI-funded expedition included dives by WHOI-operated AUVSentry. Sentry, which is a part of the U.S. National Science Foundation-funded National Deep Submergence Facility (NDSF) at WHOI, completed several dives to map the seamount and nearby seafloor and to measure the distribution of hydrothermal vent fluid in the ocean, from seafloor to surface. It also mapped the seabed in search of the ongoing search for the Samoan Clipper underwater cultural heritage site in deep water off the northwest shore of Tutuila Island. Partnering with E/V Nautilus’ remotely operated vehicles Hercules and Atalanta helped to amplify the scope of exploration.
Together, these operations will provide important data for interpretations of both water column and seafloor biological diversity and abundance, enhancing mission planning and opportunities to survey cultural heritage sites.
“We are pleased that these two unique vehicles are exploring and learning more about this exciting part of America's exclusive economic zone (EEZ),” said Andy Bowen, Director of the NDSF at WHOI, which oversees operation of Sentry. “The OECI provides us with a valuable opportunity to employ emerging technologies and techniques in truly unique ways, yielding a far more collaborative expansion of our exploration and characterization of an important and largely unexplored part of the ocean.”
The diverse array of vehicles and technologies operated by WHOI and its partners is pivotal in addressing some of the globe's most pressing scientific questions. Innovations advanced by WHOI enable researchers to gather critical data on climate change, marine ecosystems, and geological processes. By continually pushing the boundaries of ocean exploration, this technology not only enhances our understanding of the oceans but also provides essential insights that inform global efforts to protect and sustain our planet.
About Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visitwww.whoi.edu.