If sending rovers to Mars wasn’t enough, Nasa now wants to send submarines to Titan.
The space agency has outlined plans to launch the huge structure to Saturn’s largest moon by 2040.
Titan is unique in the outer solar system in that it is the only one of the bodies outside the Earth with liquid lakes and seas on its surface.
The Titanian seas, however, are seas of liquid hydrocarbons – and astronomers now what to find out what lies beneath.
Specifically, they want to send a submarine to Titan’s largest northern sea, Kraken Mare.
Sprawling over 154,000 square miles (400,000 square km), and around 300 metres (1,000 feet) deep, Kraken Mare is comparable in size to the Great Lakes in North America.
Nasa’s conceptual Titan submarine would weigh about one tonne (2,200 lb), and would use conventional electric propulsion over a 90-day mission.
Nasa says it plans to send the submarine to Titan using a winged spacecraft similar to US Air Force X-37.
The craft would survive hypersonic entry into moon’ atmosphere, release the submarine, while its sinks to the bottom of the alien ocean.
Titan’s atmosphere is largely made up of nitrogen and methane at a pressure one and half times that of Earth’s, and with a temperature of -290 °F (-179 °C).
The space agency said the submarine would be driven by a 1kW radiothermal Stirling generator that would propel the craft and also prevent it from freezing.
‘The vehicle would observe – and perhaps ultimately exploit – tidal currents in the sea, which follow a cycle once per Titan day, or 16 Earth days,’ the researchers write in the design proposal.
Overall, scientists estimate the boat will be able to travel at one metre per second (3.6 km/h, 2.2 mph).
If Kraken Mare is as deep as estimated, it could cause the proposed nitrogen ballast tanks to could condense into a liquid, making the craft sink.
Nasa has planned for this, and says a piston would enable liquid to pass liquid in and out, rather than simply relying air pressure.
The mission would primarily look for traces of compounds that could give scientists a better understanding of how life began on Earth.
‘We will investigate a full spectrum of oceanographic phenomena: chemical composition of the liquid, surface and subsurface currents, mixing and layering in the ‘water’ column, tides, wind and waves, bathymetry, and bottom features and composition,’ said Nasa.
‘Measurements of all these aspects of Titan’s hydrocarbon ocean environment can only be made through focused in situ exploration with a well-instrumented craft.
The design was developed for the Nasa Innovative Advanced Concepts Program, by Nasa Glenn’s Compass Team.