Jason Barnes, assistant professor of physics, has found waves on Saturn’s largest moon, Titan — the first waves found anywhere besides Earth.
Titan is the only moon with an atmosphere, Barnes said. Like Earth’s moon, the rest are airless.
Titan’s atmosphere is a lot like Earth’s, made up of mostly nitrogen with about the same pressure, he said.
Inside Titan’s atmosphere there are clouds, rain and lakes. It’s the only known place in the solar system, other than Earth, where this happens.
Titan and Earth also differ in many ways. Titan’s temperature is 90 degrees Kelvin which equals to negative 297.67 degrees Fahrenheit, he said. The clouds on Titan are not made of water but of liquid methane, which is the same natural gas that is used to power stoves. The natural gas is what forms the lakes and rivers on Titan.
Since lakes do exist on Titan, Barnes said, surely there must be waves on the lakes. But when first looking for waves the research showed there was no evidence of wave activity, he said.
“We thought there was wind, because Titan’s equator has sand dunes which need wind to move around, but we weren’t seeing it,” he said. “This is science, there’s what you expect and what you get and if you don’t get what you expect, then you need to rethink.”
One of the ideas for not seeing waves on Titan was that it was the wrong season, he said. Titan’s north has been in winter for many years. Titan goes around the Sun with Saturn, making a single season last for seven years. The research to find waves on Titan began in 2004. Therefore, the real search for waves has only been in the last few months.
As Titan begins to get into northern spring, a computer model suggested the winds will pick up and the possibility of seeing more waves could be probable, he said.
Another idea for the lack of waves found on Titan was that the lakes are not a liquid form like Earth’s lakes but a viscous form like molasses, he said.
The waves that were found on Titan were from a specular reflection off of the lake Punga Mare, which is a glare or a glint from the sun off of a lake, Barnes said. If there are waves, the reflection changes the shape of that glint.
“We only saw it in a couple isolated areas, which is implying that the whole lake isn’t wavy but rather we’re just getting to a point where the winds are just big enough to pick up waves in a couple different locations,” he said. “You see this on Earth too, it’s called cat’s paw.”
The angle of the waves was 6 degrees which when imputed into a computer model simulated to about two centimeters high, he said. Though this is small it shows an onset of wave activity and perhaps as Titan continues into the northern summer the winds will pick up and the waves will become larger.
It’s not a sure thing, there could be other explanations, he said.
“It’s the first indication that we might be seeing waves and we’re hoping that as we proceed with the rest of the conceding mission we’ll be able to see more and more of this as the season progresses,” Barnes said.
In the future, a mission will be sent to Titan and will land in one of the lakes, he said. When landing in the lakes, researchers and designers must know what the viscosity of the lake is — because if it’s like molasses, then instead of splashing down into the lake there will be a “splat” and a loss of a half a billion dollar spacecraft, Barnes said.
Learning about the mechanisms of wave generation is fairly understood on Earth, but it has never been tested in one-seventh gravity like on Titan, he said.
“We’re hoping to at least verify that our ideas make sense as far as how waves are generated on Earth,” Barnes said.
Emily Aizawa can be reached at [email protected]