[Update: As of August 2012 NASA has cancelled TiME, although it may resurface in future.]
The Titan Mare Explorer (TiME) is one of the missions currently being proposed to explore Saturn’s fascinating moon Titan. NASA is considering it as one of three candidates for its high-profile Discovery Missions program. The vehicle would be designed to probe the surface of Titan in much the same way NASA’s Mars Exploration Rovers have scoured the Red Planet save for one key difference: it would travel by sea rather than land.
Titan, first discovered by Dutch astronomer Christiaan Huygens on 25 March 1655 using a homemade telescope, is the largest moon of Saturn and is thought to be one of the few places in the Solar System other than Earth where life has a potential to survive in some shape or form. It was the subject of NASA and ESA’s Cassini-Huygens mission that carried out multiple flybys before dropping the Huygens probe on its surface on 14 January 2005, which returned valuable data and even images of the surface that piqued the interest of scientists worldwide.
To become humanity’s first ‘boat’ on another world, TiME will be designed to survive and study the harsh methane-ethane sea on Saturn’s moon. A mass spectrometer will be used to determine the chemical composition of the sea, while a meteorology and physical properties package will determine the depth of the sea and characterise the atmosphere above it. Cameras will also image the surface of the sea, which is thought to be relatively calm with waves no higher than half a metre, and the surrounding area.
Its destination would be Ligeia Mare, the second-largest sea on Titan at 100,000 square kilometres (39,000 square miles). Once it has splashed down, TiME will operate for about 96 days, returning data to ground control on Earth. To save on cost and weight, it will not have its own form of propulsion. Instead, it will drift solely on the wind and waves, exploring the surrounding liquid as it moves.
In addition to vast methane lakes, observations by Cassini suggest that reservoirs of water and ammonia are beneath the surface of Titan. In addition to taking measurements above and below the lake’s surface it is hoped that TiME might drift to a shoreline during its period of activity, where the surrounding land can be examined by the on-board cameras and instruments for signs of sub-surface liquid. In addition, the Advanced Stirling Radioisotope Generator (ASRG) used to power the ‘boat’ will provide power around the clock, allowing the lake to be observed both during the day and at night with the aid of a light. As a by-product of its operation the ASRG will also keep TiME warm, ensuring that its instruments keep working even when the temperature drops.
The launch window for TiME is somewhat restricted. The capsule would have to launch in 2016 to ensure it reached Titan by 2023 through a variety of gravitational assist manoeuvres. A year on Titan is equivalent to 29.5 Earth years, and by 2026 it will have passed to the far side of Saturn and will not be in direct line of sight of Earth, rendering communication impossible. Titan will not emerge into view until 2035, making the timing of the mission imperative.
Images courtesy of ESA and NASA.
What other types of vehicle do you think we could use on a world like Titan? Give us your thoughts in the comments below.