Australian scientists run rings around mysteries of Saturn's biggest moon

 

The harsh atmosphere of Saturn's largest moon Titan has been recreated in a laboratory in suburban Melbourne.

At about 1.2 billion kilometres away, Titan is an inhospitable place where cyanide rain falls from the skies and temperatures hover around minus 180 degrees - cold enough for gasses to freeze.

Using the most up-to-date data collected by NASA, La Trobe University space scientists have recreated the same conditions in a one-metre-long gas cylinder on an infrared beamline at the Australian Synchrotron in Clayton.

The ingredients needed to replicate the harsh environment of Saturn's largest moon had been identified by NASA's Cassini orbiter, which is nearing the end of a 17-year exploration of Saturn, its rings and moons.

La Trobe University astrochemist Courtney Ennis said recreating the conditions on Titan wasn't so different to cooking: it was just a matter of combining the key ingredients of nitrogen and methane and setting the temperature to minus 180 degrees using liquid nitrogen.

"That's pretty much what we do," Dr Ennis said. "It's a cryogenic experiment that forms cyanide and other gasses which form raindrops."

Unlike on Earth, where water drives the weather, creating clouds and rain, on Titan water is frozen meaning it doesn't play a role in its atmosphere.

Instead the weather is controlled by methane, which makes up about 5 per cent of the atmosphere. The other 95 per cent is nitrogen and the two chemicals react slowly with sunlight to form cyanide gas and other chemicals.

"It's that cold that stuff that is usually gas here on Earth, forms water and liquids on Titan," Dr Ennis said.

Results of the unique experiment will help researchers understand the origins of Earth, as Titan's toxic atmosphere is believed to be reminiscent of a primitive, lifeless Earth in the first billion years after our planet formed.

Gaining an insight into this cold, gassy world, some 3.6 billion years ago, will provide clues as to how life emerged - and may even indicate where to look for life forms on other planets.

While humans wouldn't last long on Titan, Dr Ennis said that didn't mean that other forms of "interesting organic chemistry" couldn't exist there.

After all, the first evidence of biological life emerged around 3.6 billion years ago - which is about a billion years after Earth formed. Given this, Dr Ennis said studying the chemistry of the atmosphere in that billion-year window would reveal the conditions that gave rise to life.

"We can look to Titan for clues," he said. "It's like Earth's chemistry frozen in time."

Quelle: The Sydney Morning Herald