A New Era of Antarctic Exploration: AUVs in Polar Science

February 19, 2015 - via Marine Technology News

Expeditions in the early 20th century were the first to combine exploration and scientific discovery in the Antarctic. While the Scientific Committee on Antarctic Research (SCAR) was set up to co-ordinate international activities back in 1958, only in the last few decades have we realized the importance of the Antarctic for marine ecology, ocean circulation and climate change. Given its remoteness, the Antarctic is more accessible than ever. The last several years have seen advancements in polar technology and the introduction of autonomous underwater vehicles (AUVs), making previously inaccessible areas open to scientific investigation and hailing the start of a new era for Antarctic exploration.

The Antarctic is one of Earth’s most extreme environments. Ice-winds, active volcanoes, unstable ice-sheets and ever-changing glaciers form the harsh landscape polar scientists must face in order to understand it’s role in ocean circulation, ecological processes and the changing climate. According to the British Antarctic Survey (BAS), it is the largest ice mass on Earth covering an area of around 14 million square km (around 58 times the size of the UK) and holds 90% of the world’s freshwater.

The annual expansion and contraction of sea ice in the Antarctic represents one of the biggest natural changes in the world.

In colder months, sea ice cover can extend more than one and a half times the size of the Antarctic continent (approximately 20 million square km), playing an important role in reflecting solar energy. In the polar summer, the same region might reduce down to 3 million square km and is a major driver of global ocean overturning circulation. In September 2014, sea ice expanded to its greatest coverage since records began in 1978, adding to the ongoing mystery of the Antarctic ice paradox. Additionally, scientists still know very little about the variations in thickness across the continent, making it a considerable focus in research.

Technologies in Extreme Environments
Traditional measurements made by visual observations on board vessels or drilling holes on the sea ice remain vital for polar data collection missions. However, difficulties in getting access to thicker areas of sea ice leaves gaps in the data.

Remote sensing techniques can be used to overcome these issues by providing observations of the physical environment from instruments mounted on aircraft or satellites.  While these observations can be useful for measuring large-scale thickness, snow cover can make the process of accurately interpreting the data difficult.

Now, with the rise of Autonomous Underwater Vehicles (AUVs) for polar applications, scientists are able to gain access to remote areas previously inaccessible. The AUVs ability to operate autonomously makes them well-suited to the exploration of extreme environments.

Over the last decade, AUVs have been successfully used worldwide for long ranging, open ocean data collection missions. While they would be useful tools for polar scientists, the use of the technology in these environments come with a number of engineering challenges, financial risks and operational difficulties.

“Recovery in open water is pretty straight forward - if there is a problem, send the vehicle to the surface,” explains Dr. Guy Williams, of the Institute of Marine and Antarctic Studies. “However, under sea ice, returning to the surface is impossible. In addition, unknown bathymetry, icebergs and ocean currents, are all additional hazards that play on the risk versus reward assessment for AUVs in Polar Regions. In addition, the larger AUV deployments tend to dominate the logistics of any voyage they are participating in.  When the long range vehicles are in the water, there is often not a lot of other marine science that can occur until it has safely returned.”

Dr. Williams was part of the international team of polar scientists who successfully produced the world’s first detailed, high-resolution 3-D maps of Antarctic sea ice using an AUV developed and operated by the Woods Hole Oceanography Institution (WHOI). While there has been studies mapping ice shelves using AUVs, none before targeting sea-ice. The new technology provided accurate measurements of ice thickness from areas that were previously too difficult to access. The project set the pace of research in the Polar Regions aimed at understanding the dramatic sea ice changes in the context of climate change.

“Previous attempts to estimate the thickness of Antarctic sea ice relied on visual observations and manual drilling - both of which are suspected to be biased to thin ice.  The AUV returns the entire thickness distribution for the sea ice floes near the ship - and a richness of data on the morphology of the sea ice in unprecedented detail,” said Dr. Williams.

Operating at 20-30m depth, the AUV was fitted with an upward-looking sonar in order to measure and map the underside of sea ice floes. Lines of data in a lawnmower pattern were merged to form high-resolution 3D bathymetric surveys of the underside of the ice. The combination of airborne measurements of sea-ice surface elevation, ice coring surveys, satellite observations and data from the AUV (called Jaguar), vastly improves scientists’ estimates of ice thickness and total sea ice volume.
 
The Importance of Internal Collaboration
International collaborations have seen notable funding opportunities for the development of technologies with the objective to significantly progress polar science over the next few years. These technologies are set to provide the resources for data collection beyond past capabilities, paving the way to new discoveries and advanced understandings into the relationship between climate change, the Antarctic and the rest of the world.

In 2014 alone, several partnerships have committed millions for the advancement of Antarctic and Antarctic research. The UK’s Natural Environment Research Council (NERC) has proposed a new ship worth $300 million, containing on board laboratories capable of analysing polar samples from both Antarctic and Antarctic research missions. The latest technology will be available for scientific users, including underwater gliders and robotic submarines. Its robust design outcompetes previous polar research vessels with the ability to advance further through hard ice-covered water and reach areas previously inaccessible by sea.

The Australian Antarctic Gateway Partnership announced $24 million Federal grant, part of which will go into developing a marine technology hub to build next generation hybrid autonomous vehicles for measurements within the polar environment.

Dr. Williams explains, “Our study has laid the foundation for this new funding, as it proved not only the value of the data returned from the AUV, but also that the AUV could be operated in the harsh Antarctic environment without loss - a key concern for funding agencies.  While this new initiative won’t directly advance this particular research (WHOI SeaBED under sea ice), it will look to develop the next ‘game-changer’ for even more advanced AUV missions, in particular long-range missions beneath Antarctic ice shelves (much deeper and more challenging).”

The grant is funded by the Australian Research Council (ARC) under its Special Research Initiatives scheme and includes the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS) and the Australian Maritime College, the CSIRO’s Oceans and Atmosphere Flagship, and the Australian Antarctic Division.

Due to its proximity to Antarctica, Tasmania is an international gateway for both scientific research and logistic support. On some level the different nations are in Antarctica for sovereignty claims, both on land and in the ocean surrounding it.  But on a scientific level, Antarctica and the Southern Ocean are critical components of the global climate system.  Observational data sets are hard-won and overall there is a paucity of data from this region compared to other parts of the globe.

Dr Alex Forrest from the Australian Maritime College, a Principal Investigator overseeing the team conducting the robotic exploration, explains “Ice is of global significance, playing important roles in ocean circulation and the functioning of polar ecosystems. However, inaccessibility makes it hard to quantify its properties at meaningful spatial scales. AUVs are potentially able to measure horizontal variability in ice properties at near centimetre resolution along kilometers of trackline, offering a fundamentally new approach to ice research. Our project will develop and apply new AUV instrumentation specifically for estimating particularly important and spatially variable properties of ice, that of the irradiance below, and biomass of algae within the ice.”

The collaboration will involve researchers from more than 10 countries and complement the Australia’s Antarctic Science Strategic Plan to understand the role of Antarctica and the Southern Ocean in the global climate system.

The Future of Polar Science with AUVs
The development of polar-adapted technologies will help moderate the associated risks with extreme environmental conditions and reduce the difficulties of accessibility. New technologies will be essential to unlocking opportunities for obtaining new data, surveying unexplored locations and advancing scientific discovery.

Firstly, a number of technical challenges for AUV operations in Polar Regions will need to be addressed, including navigation, data telemetry and autonomy. Navigation and telemetry for AUV platforms relies on satellite positioning (GPS) and communications (Iridium, ARGOS). These approaches are poorly suited to polar areas where ice cover restricts access to the sea surface and adds to the risk of AUV missions. Advancements in data telemetry and navigational systems would mitigate the financial risk associated with the loss of a platform, and more importantly, the scientific data stored on board.

Dr. Williams explains, “Greater endurance or battery life will be the key to expanding the scale of these missions, such that we can make the sort of routine measurements necessary to really get to the heart of questions such as ‘How thick is the entire Antarctic sea ice zone?’ and ‘Is that thickness changing?’.  Also, greater sophistication in the autonomy of the vehicles, together with the ability for them to work as teams and also work with autonomous vehicles surveying the sea ice from above (Unmanned Aerial Vehicles or drones).”

While deep waters remain a challenge, shallow high latitude shelves can also be resistant to measurement efforts. Ice scouring poses a serious threat to bottom mounted instrumentation and surveying shallow, ice-covered shelves will likely require a combination of methods and the capability of tolerating instrument losses while still providing useful data return. Nevertheless, surveying shallow or narrow under-ice areas is still an area of scientific interest and a focus for some projects.

Dr Forrest explains “One of the main areas of exploration that we will be targeting is under ice-shelf cavities in the marine setting. While these areas have been visited (probably less than the number fingers on one hand), there is still an amazing amount that is unknown. One of the aims of the Gateway project is to investigate the seafloor, the ice ceiling and the water column in between. While we intend to develop a vehicle that has the conventional technology, we intend to make it modular enough that we can develop new capabilities now and into the future.”

Over the next decade, these new technologies will steer the course of scientific research in the Antarctic. AUVs that are smaller in size and have a higher endurance with effective data telemetry options will eventually be needed to progress observations through the seasons, in areas which have been less accessible until now.

“While working under-ice is ideally suited for robotic exploration, it poses significant environmental challenges that we try to engineer solutions for. Every time we deploy we have unexpected challenges (e.g. Navigation, sensors, etc.). However, what makes a good team is how they respond and overcome these challenges. It is our hope that this platform will be able to provide new insights into marine ecosystem dynamics in the Antarctic but would also be applicable in other ice-covered scenarios,” Dr. Forrest.

The polar environment remains a unique place for scientific discovery and notable advances over the last few years are a result of international collaborations. In the years to come, science in the Antarctic has the potential to lead to major advances in solving vital questions for climate change and ecosystem responses, strengthening predictive models for environmental management and policy reforms.

“Our observations challenge us to explain the world around us and to develop theories that fit these explanations, such that we can predict future behaviour. Any time there is a major advance in our observational capability (new microscope, new telescope, new x-ray machine etc.), there quickly follows dramatic shifts in our understanding/theory and prediction. Measuring is believing and so with so many aspects of the polar environment now accessible by these types of platforms, we can expect a quantum leap forward in our efforts to understand how this vital component of the climate system is responding to change,” Dr. Williams.
 
Kira Coley is a freelance writer with a Marine Biology degree from University of Portsmouth and experience as a Field Scientist in various locations including Madagascar, Sicily, and Scotland. She is now a PhD researcher and regularly publishes articles and technical papers discussing key research topics in the marine sciences, oceanography and offshore industry.

(As published in the January/February 2015 edition of Marine Technology Reporter - http://www.marinetechnologynews.com/Magazine)

External link: http://www.marinetechnologynews.com/news/antarctic-exploration-polar-science-509254

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