Titan's oceanic world (above)
- Submarine will head to the largest northern sea, dubbed Kraken Mare, on Saturn's biggest satellite
- It would weigh around one tonne (2,200 lb) and travel at one metre per second (3.6 km/h, 2.2 mph)
- With sea temperature of -290 °F (-179 °C), a radiothermal Sterling generator will prevent it from freezing
- Mission will look for traces of compounds that could give a better understanding of how life began
By Ellie Zolfagharifard/Dailymail.com
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.