Lake turns to barbecue gas in Saturn's barbecue summer

NASA boffins have released a video travelogue entitled "See Beautiful Ontario Lacus", revealing the delights that travellers to the moons of Saturn might encounter during a visit to the freezing antarctic patio-gas lakes of Titan.

The film might better have been entitled "See Beautiful, Disappearing Ontario Lacus", as brainboxes analysing the same Cassini spaceprobe radar data used to generate the travelogue have discovered that Titan's antarctic lakes are rapidly evaporating as scorching local summer temperatures soar above the polar norm of -184°C.

According to boffins Alexander Hayes and Oded Aharonson of Cal Tech, the level of liquefied patio gases and methane in Ontario Lacus has fallen by a metre on average during each of the last four Earth years.

"It's really exciting because, on this distant object, we're able to see this meter-scale drop in lake depth," says Hayes. "We didn't know Cassini would even be able to see these things."

Titan is of especial interest to planetologists as it is the only body in the solar system known to have bodies of liquid on its surface which interact with clouds of evaporated fluids in a hydrological cycle like that of Earth's seas, rivers, clouds and rain.

The difference is that on freezing Titan, water behaves more as rock does on Earth. The liquids involved there are mainly methane, ethane and propane, familiar to us as the fuels LNG and LPG. Lakes such as Ontario and the Sea of Krakens at Titan's north pole evaporate to produce clouds of patio and natural gas, which then fall as rain and flow downhill into the lakes once more.

On Earth this would present some risk of the entire world exploding in a vast, global horrific barbecue mishap type fireball. However Titan, not being home to any plant life, has no free oxygen in its atmosphere and thus the fire hazard of its clouds and lakes is minimal.

According to Hayes and Aharonson, Lacus Ontario in particular has lost some six miles of shoreline to baking somewhat-less-freezing antarctic midsummer evaporation from 2005 to 2009. The Titanian year lasts 29.5 Earth years.

For those who like to know these things, Lacus Ontario is slightly smaller than the Earthly Lake Ontario at 15,000 square kilometres - roughly three-quarters as big as Wales.

There's more on the Titanian polar lake evaporation spaceprobe boffinry here courtesy of Cal Tech. There's more about the Cassini probe which brings all the data for the science from NASA here.