Titan has three large seas composed of liquid methane/ethane, the biggest of which called Kraken Mare and which will be the mission’s probable target. The sea covers about 154,000 square miles and is as deep as 525 feet in places. The craft would be designed to make a 90 day, 2,000 kilometer (1,250 mile) voyage under its waves, according to Discovery News.
However, the submersible would face some major challenges. Getting into the sea would be the first. What scientists envisage is having it attached to a spacecraft with wings, which would dive beneath the water and jettison the sub.
Another possible problem, Phys.org says is that the seas are not placid lakes, but have tides, currents and high waves, which could damage the sub. Furthermore, as Discovery News points out, the seas are incredibly cold, thought to be close to the freezing point of methane, 90 Kelvin or -298 degrees Fahrenheit (-183 Celsius).
Therefore, the sub would need a special piston-driven propulsion system and nitrogen would have to be used as ballast. Extreme Tech quotes NASA as saying “the sub would rely on a radiothermal Stirling generator to produce about 1kW of power. The concept submersible could reach speeds of about one meter per second.”
In order for it to spend long periods under surface, it would have to be powered by a radioisotope generator; a source that converts the heat produced by radioactive pellets into electricity.
Another difficulty for the mission would be NASA’s ability to communicate with the craft while it is submerged. Since that isn’t thought to be possible at the moment, the craft would have to come up regularly to the surface to transmit scientific data back to Earth.
Extreme Tech says that a rather novel way would be used to contact Earth. “Rather than introduce the complication of an orbital component to act as a link with NASA, the sub itself would have a large dorsal fin with a built-in planar phased-array antenna.”
This might help overcome complications of sending the data back over a billion miles. Furthermore, Titan is about 80 light minutes away, meaning that it would take 2hrs 40mins for NASA’s commands to get a response from the craft.
Scientists hope to find life forms or past life forms in the seas, which would be quite different from those on Earth and also gain better knowledge of our own planet’s early development.
The interplanetary, “Jules Verne-like” mission was presented at the Innovative Advanced Concepts (NIAC) Symposium by NASA Glenn’s COMPASS Team from the Applied Research Lab and has been given the name of the Titan Submarine Phase I Conceptual Design. A launch date has been tentatively set for 2040.
