Published online 18 March 2008 | Nature | doi:10.1038/news.2008.680

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Unmanned craft chart the Antarctic winter

Sea-ice study benefits from first robotic flights over Weddell Sea.

The craft are launched by elastic slingshots, and then keep themselves on track. Watch a video.BAS

A fleet of unmanned aircraft has successfully swooped around the Antarctic, gathering data from areas that would otherwise have remained uncharted.

The unmanned aerial vehicles (UAVs) were deployed by a team of researchers from the British Antarctic Survey (BAS) and the Technical University at Brunswick in Germany. The flights were made without any human intervention apart from take-off and landing, marking a first for unmanned exploration of the Antarctic.

The UAVs look like scaled-up versions of toy radio-controlled aeroplanes, but have high-tech equipment inside — once they have been launched they can fly themselves, and they are equipped to make scientific measurements.

Between October and December 2007, the 6-kilogram, 2-metre-wide planes made 20 successful 40-minute-long flights.

The planes’ engines are powered by lightweight lithium ion polymer batteries, the lifetime of which dictates how far the plane can fly. The farthest the planes flew was just over 45 kilometres, but the team suspects that they could go farther: “I’m quite sure that we didn’t reach the maximum range,” says Thomas Spiess, an engineer from the technical university who developed the UAVs and their temperature sensors.

Winter flight

The craft were used in their maiden project to measure air temperatures at very low altitudes over the Weddell Sea, which freezes in winter but is open water in summer. Researchers would like to unpick the details of whether it is warm waters or warm air that plays the biggest role in the summer ice melt. “We are measuring how much heat is flowing from the atmosphere into the sea ice below,” says Phil Anderson, project manager for the BAS. This will feed into models of how global warming will affect polar sea ice, he says.

Ideally, the planes will fly throughout the year at crucial times for sea ice: when the ice starts to form in February; in the dead of winter; when it begins to melt at the beginning of December; and in the middle of summer, when the temperature is at its warmest. “We would really like [information from] the extremes,” says Anderson.

In addition to being cheaper to run than manned craft, the AUVs might be the only way to fly over the Antarctic during winter. The BAS uses piloted planes in the Antarctic only during the summer, when light and temperatures are more favourable for flight.

Slingshot

The planes are catapulted into the air with a 25-metre-long bungee, which is wrapped up in a duvet to stop it from losing its twang in the extreme cold. The planes are preprogrammed with a course to follow, and can self-adjust their course as they fly if they are pushed off course by winds. People interfere only when they return to land.

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Landing the planes took lots of practice. “In the Antarctic, if you’ve got any cloud the sky and snow all look white and you can’t see how high the plane is,” says Anderson. “If it lands too fast it hits the snow too hard and breaks into pieces.” Then there’s the added challenge of using a joystick while wearing thick gloves. Anderson and Speiss spent hundreds of hours practising the landings on a simulator. The team hopes to automate landings in the future.

The UAVs show that autonomous flights can be a powerful tool for scientists, says Spiess. Anderson reckons that in a few years time these craft will become standard kit for exploring hard-to-reach areas, from equatorial deserts to the poles, providing reams of data on the cheap. 

Watch a video of the launch and flight.

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