The Cassini spacecraft was able to confirm the presence of rain and clouds composed of methane on Titan. In 2004, it discovered several lakes in cool regions.
Titan's tropical lake is roughly the size of the Great Salt Lake in Utah during its lowest recorded level, study lead author Caitlin Griffith, a planetary scientist at the University of Arizona at Tucson, told SPACE.com. Our work also suggests the existence of a handful of smaller and shallower ponds similar to marshes on Earth with knee- to ankle-level depths.
Griffith said any liquid deposited in the tropical surface evaporates quickly and eventually is transported by Titan's circulation to the poles, according to Space.com. But recent pictures from Cassini confirm that there are many lakes in the tropical region of the Titan, where other liquid had evaporated.
This discovery was absolutely not expected, Griffith said. Lakes at the poles are easy to explain, but lakes in the tropics are not.
Previous research suggested that there is approximately 3,425 pounds of methane per square mile on the Saturnian moon. Scientists believe must well up from below Titan's surface to explain the amount seen in the atmosphere.
Moreover, there were previous hints from the Huygens probe that landed on Titan in 2005.
The landing site, although surrounded by a vast dune field, reveals a landscape carved almost entirely by three different liquid erosion events - rainfall, flooding and seepage, Griffith said. While rainfall may have carved the downhill drainage features, the flood plain, in which the probe landed, was caused by liquid flowing from a different source of methane. In addition, a puff of methane was detected upon landing, which suggests that the site was damp.
It is unclear how long the lakes can remain on the moon without being evaporated or receding below the surface.
The possibility of persistent liquid bodies in the low latitudes ... would point to an active subsurface hydrology on Titan, said Oded Aharonson, of the California Institute of Technology, who was not part of the study team, according to National Geographic.
Aharonson believes the tropical lakes could one day be a commodity for Earthlings.
If the equatorial regions have subsurface methane emerging to the surface, he said, that would be a viable source.