Teleoperation and robotics under ice: Implications for planetary exploration

This paper describes the methods used to operate the underwater robotic vehicle Nereid Under Ice (NUI) beneath the Arctic ice pack during expeditions in 2014 and 2016 and discusses to what extent those methods might be transferable to future robotic missions to our Solar System's ocean worlds. NUI is capable of operating both autonomously and, with the addition of a hair-thin unarmormed fiber optic tether, as a remotely operated vehicle. We operated NUI in both modes during the expeditions. Overlying ice makes operating robotic vehicles on the sea floor challenging because sea ice moves and ice breakers typically cannot hold station with equipment over the side. Operators on board the ship and the vehicle will drift apart during a mission, often by kilometers. This complicates navigation, communication and recovery. NUI's unique tether enables standoff distances of several kilometers while under direct human control. Autonomous operation and recovery operations in case of tether loss rely on a combination of onboard autonomy and acoustic communication. We report the design and operation of NUI's unarmored microtether, the hybrid control methodology that enables operating the vehicle directly or semi-autonomously and handles forced transitions between modes in case of tether loss, and the use of acoustics for communication and navigation. We conclude by discussing what aspects of the technology already developed for under-ice robotic exploration of deep ocean environments and presented here, would be most readily transferable to future NASA missions.