Photo: NASA/JPL/Space Science Institute

When we think of machines probing the surfaces of other planets, maybe we picture the Mars rover, with six rugged wheels rambling over the rocky alien terrain. We might not necessarily consider something that resembles a sea turtle.

Scientists at the Spanish engineering firm SENER are working on the concept of a swimming interplanetary probe, but this one would travel to Saturn’s moon Titan. Titan is very organically diverse, dotted with lakes, dunes and seas. Researchers are particularly interested in Ligeia Mare, a lake of hydrocarbon a couple hundred meters across. Their goal is to create a machine that would explore the lake’s shoreline, then paddle out farther to probe the lake’s depths (which most likely only reach about 30 feet). To design the machine, the engineers are borrowing elements from a Soviet amphibious vehicle and a Mississippi River paddleboat.

Researchers are mostly keen to find out how the hydrologic cycle works on Titan: How liquid evaporates and eventually rains down on the surface… if indeed it does. A probe is definitely needed, since Titan is quite inhospitable to life. The atmosphere would be something akin to an oil refinery, with methane raining down from the sky creating an orange fog. It’s also cold, about 290 degrees Fahrenheit below zero.

This would be an expensive undertaking for NASA or any other space exploration agency. Fortunately, the engineers at SENER thought of that. To save money, they could forgo the boat’s paddles, letting it move with Ligeia Mare’s currents and collect information as it floats along.

It wouldn’t be the first probe sent to Titan. The Huygens probe landed there in 2005, and has sent back valuable information about the planet’s surface and atmosphere.