Here we present the design of a custom water sampling system for use on the underwater robot Icefin. The goals of this instrument are to collect discrete water samples in a compact form factor, ...operate in extreme underwater environments including high pressure and low temperature settings, and maintain a simple low-cost design. To achieve these objectives the system integrates a fluidic manifold, several compact solenoid pumps and valves, electronic controls, and an oil filled housing. A first-generation version of the water sampler was successfully tested on the underwater robot Icefin during ocean deployments in McMurdo Sound, Antarctica. A second-generation version of the system with a 3D printed manifold and improved capabilities has since been developed and undergone preliminary lab tests.
Ocean conditions near the grounding zones of Antarctica’s ice shelves play a key role in controlling the outflow and mass balance of the ice sheet. However, ocean observations in these regions are ...largely absent. Here, we present a detailed spatial survey collected with an underwater vehicle in a basal crevasse located in the ocean cavity at the Ross Ice Shelf grounding zone. The observations depict fine-scale variability in ocean forcing that drives asymmetric melting along the lower crevasse sidewalls and freezing in the upper reaches of the crevasse. Freshwater release from melting at depth and salt rejection from freezing above drives an overturning circulation. This vertical circulation pattern overlays a dominant throughflow jet, which funnels water parallel to the coastline, orthogonal to the direction of tidal currents. Importantly, these data reveal that basal crevasses influence ocean circulation and mixing at ice shelf grounding zones to an extent previously unknown.
In situ observations reveal how ocean physical properties drive ice melting and freezing within an ice shelf basal crevasse.
Abstract
Several worlds in our solar system are thought to hold oceans of liquid water beneath their frozen surfaces. These subsurface ice and ocean environments are promising targets in the search ...for life beyond Earth, but they also present significant new technical challenges to planetary exploration. With a focus on Jupiter’s moon Europa, here we (1) identify major benefits and challenges to subsurface ocean world science, (2) provide a multidisciplinary survey of relevant sample handling and life detection technologies, and (3) integrate those perspectives into the Subsurface Science and Search for Life in Ocean Worlds (SSSLOW) concept payload. We discuss scientific goals across three complementary categories: (1) search for life, (2) assess habitability, and (3) investigate geological processes. Major mission challenges considered include submerged operation in high-pressure environments, the need to sample fluids with a range of possible chemical conditions, and detection of biosignatures at low concentrations. The SSSLOW addresses these issues by tightly integrated instrumentation and sample handling systems to enable sequential, complementary measurements while prioritizing preservation of sample context. In this work, we leverage techniques and technologies across several fields to demonstrate a path toward future subsurface exploration and life detection in ice and ocean worlds.
Thwaites Glacier is one of the fastest-changing ice-ocean systems in Antarctica
. Much of the ice sheet within the catchment of Thwaites Glacier is grounded below sea level on bedrock that deepens ...inland
, making it susceptible to rapid and irreversible ice loss that could raise the global sea level by more than half a metre
. The rate and extent of ice loss, and whether it proceeds irreversibly, are set by the ocean conditions and basal melting within the grounding-zone region where Thwaites Glacier first goes afloat
, both of which are largely unknown. Here we show-using observations from a hot-water-drilled access hole-that the grounding zone of Thwaites Eastern Ice Shelf (TEIS) is characterized by a warm and highly stable water column with temperatures substantially higher than the in situ freezing point. Despite these warm conditions, low current speeds and strong density stratification in the ice-ocean boundary layer actively restrict the vertical mixing of heat towards the ice base
, resulting in strongly suppressed basal melting. Our results demonstrate that the canonical model of ice-shelf basal melting used to generate sea-level projections cannot reproduce observed melt rates beneath this critically important glacier, and that rapid and possibly unstable grounding-line retreat may be associated with relatively modest basal melt rates.
Forward-looking sonar is one of the most common and powerful instruments available for use in imaging underwater environments. Here, we explore the utility of these sonar sensors for mosaicking, ...mapping and topography reconstruction of areas of interest in our target under-ice and underwater environments. This is a difficult problem due to the noise in the sonar images as well as the changing appearance of objects when views from different points. Here we address the problem of sonar image alignment through sensor fusion with navigation instruments to provide an initial relative placement between sonar frames. We also discuss the use of such forward looking sonar sensors to build 3D point clouds of the ice topography.
Icefin is a custom designed remotely or autonomously operated vehicle (ROV/AUV) for sub-ice deployments in polar environments with a primary focus on modularity for deploying multiple payloads ...throughout a season to characterize the under-ice environment. Over the past six years the vehicle has undergone numerous design improvements to become a stable and robust platform. The current primary vehicle design was proven during the 2018 field campaign. With the success of that season, a second vehicle was built to accommodate two field campaigns in austral summer 2019-2020, wherein the vehicle dual Icefin vehicles were deployed through ~600m hot water drilled boreholes to investigate the grounding zones of Thwaites Glacier and the Ross Ice Shelf. Presented here is an overview of the engineering design updates that were incorporated from the 2017 season. Also presented are results and lessons learned from the 2019 deployments.
Icefin is a custom remotely or autonomously operated vehicle (ROV/AUV) designed for sub-ice deployments in Antarctica with a focus on portability for remote field deployments and modularity to ...accommodate various payloads to characterize the under-ice environment. A prototype iteration of the vehicle was deployed in McMurdo, Antarctica in 2014 and provided data as well as valuable lessons learned. Since then the vehicle has been refined significantly into a more capable and reliable platform that was deployed during the 2017 austral summer Antarctic season (October 2017 - December 2017). Presented here is an overview of the design updates, including mechanical, electrical and software changes that were incorporated in developing the baseline Icefin platform. Also presented are lessons learned and early results from the 2017 deployment of the redesigned vehicle, as well as changes integrated into the vehicle for its 2018 field season.
Icefin is a hybrid ROV/AUV, designed to function as a robotic oceanographer in Antarctic under-ice waters. Autonomous command, control, and navigation of robotic platforms in remote sub-ice ...environments is highly challenging, as well as a sufficiently specialized application such that it does not benefit from the foundation of a wide community of opensource research. Here we present our approach and lessons learned in addressing this challenge through the integration of commercial off-the-shelf and open-source tool sets while working inside a framework that supports rapid, modular expansion of the vehicle's command and control software.
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