William Atkins
Thursday, 31 July 2008 22:11
Science -
Space
Page 2 of 3
Described as
“a mirror-smooth lake on the surface of the smoggy moon Titan,” Lake Ontario Lacas is drawn by an artist on NASA’s website “
Titan's Ethane Lake.”
According to the NASA news release “
NASA confirms liquid lake on Saturn moon,”
“The ethane is in a liquid solution with methane, other hydrocarbons and nitrogen. At Titan's surface temperatures, approximately 300 degrees Fahrenheit below zero, these substances can exist as both liquid and gas. Titan shows overwhelming evidence of evaporation, rain, and fluid-carved channels draining into what, in this case, is a liquid hydrocarbon lake.”
It continues,
“Earth has a hydrological cycle based on water and Titan has a cycle based on methane. Scientists ruled out the presence of water ice, ammonia, ammonia hydrate and carbon dioxide in Ontario Lacus. The observations also suggest the lake is evaporating. It is ringed by a dark beach, where the black lake merges with the bright shoreline. Cassini also observed a shelf and beach being exposed as the lake evaporates.”
The discovery was made using a visual and mapping instrument, called the Visual and Infrared Mapping Spectrometer (VIMS), onboard the Cassini spacecraft. It has been known that Titan contains numerous lakes—in fact, some scientists thought huge oceans exist—however, what wasn’t known was whether these bodies contained liquid or solid matter.
The Cassini instruments bounced infrared radiation off the surface of Titan. When the radiation returned to Cassini the instruments were able to confirm the chemical composition of different materials and the presence of liquid by the way the materials absorbed and reflected the radiation (light)
The team leader of Cassini’s visual and mapping instrument, Bob Brown (University of Arizona, Tucson, U.S.A.), stated
"This is the first observation that really pins down that Titan has a surface lake filled with liquid.”
Titan’s atmosphere is a mixture of about 95% nitrogen and 5% methane. This research study also found ethane and several other simply hydrocarbons in the atmosphere. It is stated in the NASA news release that
“Ethane and other hydrocarbons are products from atmospheric chemistry caused by the breakdown of methane by sunlight.”
Read more about the Cassini-Huygens mission and the Nature article discussing the discovery on Titan, all on page three.
