Quirks & Quarks

NASA is designing a sub to explore Titan's methane oceans

Scientists find NASA's quest to explore Titan's seas may be easier than we thought
A submarine concept that would explore the depths of Saturn's moon Titan (NASA)

NASA's plans to send a submarine to Titan

NASA's plan to send a submarine to Titan is more practical than previously thought, according to new research from Washington State University. Titan is the largest of Saturn's eight moons and is the only other body in our solar system with an atmosphere with liquid on the surface. It's not liquid water though. Titan's surface is covered in seas similar to liquid natural gas - a mix of methane and ethane. NASA is designing a submarine to explore the seas of Titan, but since these seas are nothing like our watery oceans, they face unique challenges in designing the submarine. 

The challenges of designing a submarine to explore Titan's alien seas 

One big mystery was how the three bodies of water of Titan differ in their buoyancy. One lake is almost entirely methane while another is almost 70 per cent ethane and only 30 per cent methane. Designing a submarine that can cope with the different densities of liquid might have posed a real problem. However Dr. Ian Richardson, a postdoctoral researcher from Washington State University, has found that these drastically different compositions don't need to affect the submarine design too much. 

A further complications is that the nitogren gas from the atmosphere that dissolves into the seas can also be a problem. "The nitrogen can cause problems because it wants to come out of solution when you agitate the mixture at all," says Dr. Richardson. "The submarine will have a nuclear-powered core, so it's constantly putting off heat. And that heat can cause nitrogen bubbles to form and cause effervescence, which is essentially boiling. So you get small nitrogen bubbles coming out of solution, which could affect the sensors, it can affect the ballast systems, and it can affect the propeller and propulsion of the submarine." Dr. Richardon said when they tested for this effect in the lab, "We actually found that it won't be a problem on Titan with the current design."

Timeline for the mission

The planning is still in the design phase. "The current design is about six-metres in length, a metre wide, and two-metres tall and weighs 1,200 kilograms. So it looks fairly similar to the submarines we have here on Earth, just a big, metal cylinder with some propellers on the backend." 

A launch window coming up in the 2030s means it is possible that someday we will be seeing an autonomous submarine cruising the seas of Titan and sending us back valuable data.

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