A wind-powered USV called the saildrone has become the first unmanned system to circumnavigate Antarctica.

Known as SD 1020, the vehicle, equipped with a suite of climate-grade sensors, collected data in previously unchartered waters, which will offer insights into ocean and climate processes.

SD 1020 launched on Jan. 19 of this year from Southport in Bluff, New Zealand, and returned to the same port on Aug. 3. Over the course of 196 days, the USV sailed more than 13,000 miles around Antarctica, surviving freezing temperatures, 50-foot waves, 80 mile per hour winds, and collisions with giant icebergs along the way.

According to Saildrone, the Southern Ocean “plays a key role” in regulating heat and carbon for the planet. Because of how remote and inhospitable it is, even large ships try to avoid it in the winter, Saildrone notes, but thanks to the nimbleness and robustness of the USV, the saildrone was able to not only survive the Southern Ocean winter, but it was also able to stream back important new data from previously unsampled territory.

“One of our largest ‘blind spots’ in terms of our climate knowledge and its future prediction lies in the Southern Ocean. This is mostly due to the serious lack of observations, in particular in winter, in this remote and harsh environment. This leads to a poor understanding of how these polar oceans function,” explains Sebastiaan Swart, co-chair of the Southern Ocean Observing System (SOOS).

“These exciting, high-resolution observations from Saildrone during its circumnavigation of the Antarctic provide valuable ground-based datasets for scientists to understand the Southern Ocean better and evaluate the models we use to predict weather and climate.”

The saildrone carried an instrument developed by the National Oceanic and Atmospheric Administration (NOAA) to measure carbon fluxes “very precisely.” This allowed the USV to provide important new data on the rates of carbon uptake in the Southern Ocean.

“There’s a lot left to be learned about the ocean’s uptake of CO2 emissions, especially in the Southern Ocean. Up until a few years ago, the Southern Ocean was understood to be a large CO2 sink,” says Dr. Adrienne Sutton, an oceanographer with the NOAA Pacific Marine Environmental Laboratory (PMEL) Carbon Group, which has been involved in all Saildrone missions related to CO2 to date.

“Yet, that understanding was based primarily on observations made from ships that steer clear of the harshest weather in the Southern Ocean, leaving winter months undersampled.”

Sutton notes that thanks to the deployment of carbon sensors on profiling floats—part of the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project—scientists started to get a “broader seasonal distribution of observations,” and they found less of a CO2 sink than previously thought.

Capable of measuring seawater pH, the SOCCOM floats use empirical relationships to calculate seawater partial pressure of carbon dioxide (pCO2), which introduces “some uncertainty relative to a direct measurement.” Saildrone says that this has led to an “active discussion” surrounding “the uncertainty in the calculated pCO2 from the float measurements and whether the weakened CO2 sink, which was observed by the floats 2014 – 2017, was just natural variability.”

During the mission, the saildrone rendezvoused with a few of the SOCCOM floats.

“Having another autonomous platform that can survive the Southern Ocean is both a technological feat and an opportunity to get us closer to solving the ocean CO2 sink puzzle!” Sutton says.

“Preliminary results suggest that we also observed CO2 outgassing during winter months in the same region as the floats measured previously. CO2 outgassing from the ocean to the atmosphere occurs when ocean pCO2 levels are higher than atmospheric levels.”

The saildrone also took reference measurements near moored buoys.

Saildrone says that it is building a global fleet of USVs, with the goal of planetary coverage.

“In terms of carbon and heat, the Southern Ocean is by far the most important ocean. Globally, the Southern Ocean takes up about half of all carbon and 75% of all heat that enters the ocean,” Swart says.

“This makes it disproportionately more important to place efforts and resources, such as those occurring by robotic platforms like Saildrone, into obtaining more scientific measurements in this polar region.”

This means that the Southern Ocean is a “key priority to instrument” for Saildrone. With this in mind, the company plans on deploying a fleet of vehicles to monitor the Southern Ocean on a persistent basis, which would mean a fleet of 10 to 20 saildrones sailing around Antarctica year-round.

“A monitoring system for the Southern Ocean is one of our highest priorities,” Saildrone founder and CEO Richard Jenkins says.

“Understanding heat and carbon fluxes, fish populations, and ocean acidification in the Southern Ocean are absolutely key to improve the understanding of our climate, and to the sustainability of life on this planet. Only very significantly increased measurement will enable meaningful predictions for the future.”