The first interplanetary nautical craft may be a boat to explore the methane seas of Titan. A proposed mission to Titan would explore some of its largest seas, including Ligeia Mare (pictured) or the Kraken Mare, both of which are in the northern hemisphere of the foggy moon of Saturn. The concept has been studied for over two years by scientific team led by Ellen Stofan of Proxemy Research, Inc. in Washington DC, and has recently been submitted to NASA.
The concept is under consideration by NASA to be one of the Discovery Class missions – low-cost, high-return missions, which include the MESSENGER and Kepler missions. If chosen, the Titan Mare Explorer (TiME), could launch as early as January of 2015, and would make port at Titan in June of 2023. The total proposed cost of TiME is currently estimated at $425 million. Stofan described the proposal at this year’s American Geophysical Union meeting in San Fransisco, CA.
Lakes, seas, and rivers were discovered on Titan by the Cassini spacecraft in 2005. Since then, the weather and climate patterns of the moon have been scrutinized by scientists, leading to the discovery of both fog and rain.
Of course, the proposed boat wouldn’t be the first craft to land on Titan – that distinction is held by the Huygens probe, which as part of the Cassini mission landed on Titan on January 14th, 2005 and for three hours took images and scientific data which it sent back to Earth. Huygens touched down on dry land, though it was designed to operate on either land or ocean.
Proposed instruments for the boat include a mass spectrometer, sonar, cameras and meteorology instruments. TiME would investigate the chemical composition of the seas of Titan, as well as monitor the cycle of ethane and methane on the moon (called the “methane-ologic” cycle), a process that scientists are just beginning to understand. The sonar would be used just like it is on submarines and boats here on Earth – to map the depth of the seas, as well as get an accurate image of the sea bottom.
Since the cloudy and foggy surface of Titan sees little sunlight, the boat is proposed to be powered by an Advanced Stirling Radioisotope Generator. These types of engines, called Stirling engines after the inventor, Robert Stirling, use a radioactive source such as plutonium to heat a gas in one chamber, and as it flows to a cooler chamber the flow is turned into mechanical energy with a very high rate of efficiency.
If the boat is seaworthy, it may set a precedent to give us Earthlubbers a chance at understanding the only other body in our Solar System with lakes and seas on its surface (though Europa and Enceladus are thought to have watery oceans under their crusts). By comparing the methane-ologic cycle on Titan with the Earth’s hydrologic cycle, scientists could gain a more intricate knowledge of the large-scale impact of these cycles.