Professor Louis L. Whitcomb and Dr. Christopher McFarland are returning from an expedition in the arctic oceans after successful testing the new ROV Nereid-UI's first under-ice deployments.

News note from Louis

Dear Colleagues:

We are presently at 71° 10.627′ N 17° 19.843′ E in transit to Tromso, Norway, after conducting Nereid-UI's first under-ice deployments during the July 2014 R/V Polarstern PS86 expedition at 86° N 6 W° in the Arctic Ocean - near the Aurora hydrothermal vent site on the Gakkel Ridge approximately 200 km NE of Greenland.  We conducted 4 dives to evaluate and develop Nereid-UI's overall functioning and its individual engineered subsystems including energy storage, propulsion, ice-relative underwater navigation, fiber-optic tether, underwater acoustic telemetry, radio-frequency (RF) telemetry, command and control, acoustically controlled semi-autonomous operation, buoyancy, emergency localization, and launch/recovery operations.  We also conducted Nereid-UI's first science operations including targeted high-resolution vertical profiling; constant distance from ice or constant depth survey, primarily for IR/radiance measurements and electronic still camera imaging, multibeam under-ice topography mapping, high-definition optical imaging of the upper water column, under-ice biology, and under-ice topography.

Each of the four dives commenced with deployment of the acoustic telemetry and ranging package from the ship's moon pool. Nereid-UI and its mated tow-body/depressor were then deployed from Polarstern‘s starboard deck just aft of the CTD station into an open pool of water created by the ship's main propellers and bow/stern thrusters.  After preliminary checkout of Nereid-UI on the surface, Nereid-UI was piloted to 26 m depth while the depressor/towbody was lowered to about 23 m depth, where a full checkout of all vehicle systems was completed.

After remote-controlled release of the tow-body from the depressor, Nereid-UI was piloted at 40 m depth to its planned site of operation under a floe. Dead-reckoning (Ice-locked Doppler sonar and north-seeking gyrocompass) complemented by acoustic ranging provided excellent navigation throughout the dives, and supports closed-loop control of heading, depth, and XY position relative to the ice. Science operations included multibeam transects of under-ice topography, precision vertical profiles for the bio-sensor suite and IR/radiance sensor suite, IR/radiance/multibeam transects at constant depth interlaced with vertical profiles and upward-looking digital still-camera surveys of the ice, inclluding areas rich with algal material.   The fiber-optic tether remained intact throughout most of all 4 dives.  Consistent with the Nereid-UI concept of operations, in 3 of 4 dives the fiber-optic tether eventually failed, and the vehicle was then commanded acoustically in a series of short-duration maneuvers to return to Polarstern before surfacing in an open pool on Polarstern's starboard side.   RF communications enabled the pilot to maneuver the vehicle around small surface floes to the ship's side for recovery.

These preliminary dives were each 5 hours in duration, with Nereid-UI ranging up to 800 m from Polarstern at a maximum depth of 45 m and traveling up to 3.7 km under the moving sea ice.

The Woods Hole Oceanographic Institution and collaborators from the Johns Hopkins University and the University of New Hampshire have developed for the Polar Science Community a remotely-controlled underwater robotic vehicle capable of being teleoperated under ice under remote real-time human supervision.  The Nereid Under-Ice (Nereid-UI) vehicle will enable exploration and detailed examination of biological and physical environments including the ice-ocean interface in marginal ice zones, in the water column of ice-covered seas, at glacial ice-tongues, and ice-shelf margins, delivering realtime high-definition video in addition to survey data from on board acoustic, optical, chemical, and biological sensors. The vehicle employs a novel lightweight fiber-optic tether that will enable it to be deployed from a ship to attain standoff distances of up to 20 km from an ice-edge boundary under the real-time remote control of its human operators, providing real-time high-resolution optical and acoustic imaging, environmental sensing and sampling, and, in the future, robotic intervention. The goal of the Nereid-UI system is to provide scientific access to under-ice and ice-margin environments that is presently impractical or infeasible.

The Nereid-UI at-sea team on Polarstern PS86 is Christopher R. German (science lead and PI of the NOAA grant that funded these PS86 Nereid-UI ops, and CO-PI on the Nereid-UI NSF MRI development grant), Michael V. Jakuba (Nereid-UI engineering and ops lead), John Bailey, Steve Elliott, Christopher Judge, and Stefano Suman, all from WHOI, and Christopher McFarland and myself from JHU.  I am a CO-PI of Nereid-UI NSF MRI Grant that funded Nereid-UI's development.  Christopher McFarland is the lead developer of the ship-based navigation system that we used to remotely guide Nereid-UI, submerged under moving ice, back to the ship.

Nereus development was supported by NSF OPP (ANT-1126311), WHOI, James Family Foundation, and George Frederick Jewett Foundation East. Nereid-UI PS86 operations were supported by NOAA-OER, PS86 Chief Scientist Antje Boetius, and the Captain and Crew of the R/V Polarstern PS86.

We are grateful to the many engineers and scientists who supported the Nereid-UI development and operations efforts before and during this expedition including the WHOI Deep Submergence Operations Group and the WHOI Acoustic Communications Group. The ships officers, crew, science party, and Chief Scientist Dr. Antje Boetius have been wonderful.

More information about Nereid-UI and the multiple scientific and engineering objectives of this expedition are available here http://www.whoi.edu/main/nereid-under-ice and here http://www.marum.de/en/ARK-XXVIII3.html