Alien ocean helps test NASA outer space submarine

The researchers re-created a Titan ocean in a laboratory. They have published a paper on their work in the journal, Fluid Phase Equilibria.

Titan is of particular interest to researchers because it is similar to earth in one important way, it holds liquid. Unlike almost anywhere else in the solar system, the moon’s surface includes oceans, rivers and clouds, and like on earth, it can rain. But, instead of water, the hydrological cycle is based on methane.

Because of the possible lessons it could provide here on Earth, NASA has been studying Saturn and its moons for more than a decade with data collected from the Cassini spacecraft.

The submarine that the agency is designing will have to operate autonomously. It will need to study atmospheric and ocean conditions, move around sea beds, and hover at or below the surface.

The engineering is even trickier because, unlike the nearly homogeneous water in earth-based oceans, the concentration of ethane and methane can vary dramatically in the Titan oceans and change the liquid’s density properties.

Ian Richardson, a former graduate student in the School of Mechanical and Materials Engineering, got the chance to tackle how NASA might build a submarine for the extreme conditions. In WSU’s cryogenic lab, which studies materials at very cold temperatures, Richardson re-created the atmosphere of Titan and tested how a small heated machine might work under such conditions.

Richardson, who holds a bachelor’s degree in mechanical engineering from WSU, has had a longtime interest in space and space exploration technologies.

He was WSU’s first-ever recipient of a NASA Space Technology Research Fellowship, which included an internship at NASA’s Glenn Research Center in Cleveland, Ohio. It was while working as an intern on a separate problem that a NASA scientist approached him with the problem of designing a submarine for Titan.

“My research just took a right turn, and I went with it,” said Richardson. “It’s a crazy experiment, and I never thought I would have had this opportunity. It’s been a very fun and challenging experimental design problem.”

The WSU research team built a test chamber that housed the liquid mixture at very cold temperatures to simulate the seas of Titan. They added a two-inch, cylinder-shaped cartridge heater that would approximate the heat that a submarine would create.

One of the biggest challenges for researchers was understanding bubbles in the Titan seas. Add a submarine powered by a heat-producing machine into the very cold Titan liquid, and nitrogen bubbles will form. Too many bubbles would make it hard to maneuver the ship, see, take data and manage ballast systems.

The next big problem, said Richardson, was getting a video in difficult conditions. Their study was conducted at 60 pounds per square inch of pressure and nearly -300ºF.

Richardson’s group engineered a solution using an optical device called a borescope and video camera that could withstand the low temperatures and high pressures to visualise what was going on within the test chamber. “Those aren’t the friendliest conditions,” he said. “You have to come up with creative solutions.”

The group also studied the freezing temperatures for methane and ethane lakes and determined that, because of a small amount of nitrogen in the liquid, the lakes freeze at lower temperatures than would be expected: 75 K, or -324ºF, instead of 90.5 K.

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Image credit: Washington State University.