May 23, 2013
Storm Season Ahead: Titan Gearing Up For Spring And Summer Seasons
Lee Rannals for redOrbit.com - Your Universe Online
NASA scientists are predicting that Saturn's moon Titan is in for some wild weather during its spring and summer seasons.The space agency said it believes that as the seasons change in Titan's northern hemisphere, waves could ripple across the moon's hydrocarbon seas, and hurricanes could start swirling around in these areas. Data from NASA's Cassini spacecraft helped create the models that led to the predictions.
"If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan," said Scott Edgington, Cassini's deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We know there are weather processes similar to Earth's at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can't wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer."
Titan's north polar region was dark when Cassini first arrived at the Saturn system in 2004. However, sunlight has begun creeping in on the moon's northern hemisphere since August 2009. The Saturn moon's seasons take about seven Earth years to change. Titan will not be at the height of its summer season until 2017.
The new model improves on previous ones by simultaneously accounting for Titan's gravity; the viscosity and surface tension of the hydrocarbon liquid; and the air-to-liquid density ratio.
"We now know that the wind speeds predicted during the times Cassini has observed Titan have been below the threshold necessary to generate waves," said Alex Hayes, a member of Cassini's radar team who is based at Cornell University. "What is exciting, however, is that the wind speeds predicted during northern spring and summer approach those necessary to generate wind waves in liquid ethane and/or methane. It may soon be possible to catch a wave in one of the solar system's most exotic locations."
According to the new prediction, Titan needs winds of 1 to 2 miles per hour to generate waves on its lakes. Winds of that speed could be producing waves about a half a foot high. Hurricanes on the Saturn moon could increase surface wind over the seas to possibly 45 miles per hour.
"For these hurricanes to develop at Titan, there needs to be the right mix of hydrocarbons in these seas, and we still don't know their exact composition," said Tetsuya Tokano of the University of Cologne. "If we see hurricanes, that would be one good indicator that there is enough methane in these lakes to support this kind of activity. So far, scientists haven't yet been able to detect methane directly."
Titan has more up its sleeve than seemingly tamer weather than what we experience on Earth. Scientists believe the moon's environment could eventually host life. Researchers wrote in the journal Nature Communications that complex organic chemistry could eventually lead to the building blocks of life on Titan.
Image 2 (below): Ligeia Mare, shown in here in data obtained by NASA's Cassini spacecraft, is the second largest known body of liquid on Saturn's moon Titan. It is filled with liquid hydrocarbons, such as ethane and methane, and is one of the many seas and lakes that bejewel Titan's north polar region. Cassini has yet to observe waves on Ligeia Mare and will look again during its next encounter on May 23, 2013. Image credit: NASA/JPL-Caltech/ASI/Cornell