Swimming Robot Tested for Billion-Mile Trip to Saturn Moon

By Katie Worth

Where do you get a robot ready to visit a lake a billion miles away?

The glacier-fed Laguna Negra (map) in the Chilean Andes, where NASA and SETI Institute scientists have been testing a floating robot whose successors may eventually parachute into a sea on Titan, Saturn’s largest moon.

NASA lake lander picture
The NASA Lake Lander robots lands on Titan’s lake in an artist’s imagining. Illustration courtesy NASA/JPL

It’s not filled with liquid methane, nor is it -297 degrees Fahrenheit (-182 degrees Celsius), but otherwise Laguna Negra does a passable impression of an alien sea. That’s because it’s surrounded by a barren environment with a thin atmosphere and is vulnerable to storms, avalanches, and possibly volcanoes.

Due to global warming, the glacial lake is also rapidly changing, ideal circumstances for a robot being taught to recognize shifts in a fluid environment.

Titan has the distinction of being the only other body in our solar system known to have stable liquid on its surface. That liquid is mostly made of the gases methane and ethane, but the fact that the moon has seas, lakes, rain, and glaciers make it closer to Earth than anything else in our solar system. (Related: “Saturn Moon Has Tropical ‘Great Salt Lake,’ Methane Marshes.”)

The lander’s science team, led by SETI astrobiologist Nathalie Cabrol, first launched the Planetary Lake Lander in Laguna Negra in 2011. The prototype robot has spent the last two years exploring its surroundings, determining the lake’s size and depth, measuring its pH, and observing all meteorological phenomena.

It’s not ready yet: The lander’s instruments are designed for a terrestrial environment, and the current version is far too heavy to be sent into space. But those evolutions will come, said Cabrol.

“Right now we’re at the same place we were 10 or 15 years ago, when we were starting to test Mars rovers in the desert,” she said.

Smart Robot

Through this winter, the Lake Lander is exploring Laguna Negra unsupervised, but the SETI team is preparing for another field visit in a few months, when they will refine the most ambitious part of the project: investing the robot with intelligence. (Related: Teaching Robots to Anticipate Human Actions.”)

Until now, extraplanetary robotic explorers have been micromanaged from Earth.

But communication between Earth and Titan would take hours each direction, so the robot must be built with some decision-making and problem-solving capacity. Also, since rain and other weather phenomena occur on Titan, an exploration robot would need to know when something unusual is happening so it can stop what it’s doing and pay attention.

To do this, the robot will have to become familiar with its “normal” environment, and detect when something abnormal happens. For example, if the robot floats near shore, it will be able to recognize that and begin taking photographs and a series of scientific measurements.

This scientific autonomy is an evolution that is likely to take hold in all future extraplanetary robots, not just those that go to Titan, Cabrol said. (Read “Robot Revolution? Scientists Teach Robots to Learn.”)

“We’re not only building a robot, but a new generation of robots,” she said. “The new generation will not just be sitting around waiting for us to tell them what to do.”

Life on Saturn Moon?

The world’s space agencies have already sent one probe to Titan.

In January 2005, NASA and the European Space Agency dispatched the UFO-shaped Huygens Probe parachuting through Titan’s thick brown atmosphere. It landed on a patch of squishy hydrocarbon mud, then transmitted data for more than 90 minutes before its battery died and it went silent.

Since then, several missions to Titan have been proposed, including a nautical robot to explore a sea near Titan’s North Pole. However, that proposal lost to a 2016 Mars mission in the last round of NASA exploration funding.

Saturn’s largest moon also holds special interest for science because of the possibility that life in some form exists there, or has in the past. (See “Is Saturn Moon’s Haze Old Enough for Life?”)

The lander project’s lead engineer, Trey Smith, noted that because of Titan’s hydrocarbon atmosphere and lakes, there is likely “some interesting organic chemistry going on there.”

“No living thing we know of on Earth could survive on Titan,” he said, “but that doesn’t mean there isn’t some other exotic form of life there.”

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