The images showed three unusual brightenings over fields of dunes near the equator of Titan, Saturn’s largest moon. Captured by the Cassini spacecraft, the images provided a glimpse of an environmental phenomenon only otherwise seen on Earth and Mars: dust storms.
“We know our planet is really special, but this helps us understand that our sibling bodies in the solar system are also really special and they can tell us a lot of things about our own planet Earth,” said BYU geology professor Jani Radebaugh, co-author with an international team of scientists who recently published their findings in top journal Nature Geoscience.
Previous images from Cassini, which Radebaugh has been analyzing since it first arrived at Saturn in 2004, showed that Titan’s surface had massive dune fields, but planetary scientists — until now — hadn’t seen any evidence that those dunes moved.
In these infrared images, the short-lived brightenings, unlike Titan’s typical methane rain and clouds, appeared to be lower — closer to the moon’s surface — and looked more like moving organic particles. With additional analysis, the team discovered that during the moon’s spring equinox, winds at Titan’s equator were strong enough to move the fine particles among the sands into dust storms.
“We’ve seen all these sand dunes but didn’t have anything to tell us they’re actually active,” said Radebaugh. “And this is a piece of evidence that would suggest wind is moving fast enough to pick up sand grains and blow them around so that the dunes may be active today.”
Because the dunes on Titan aren’t surrounded by oceans, plants or physical barriers, Radebaugh explained, they can move and change and grow unobstructed. Studying that movement, she added, can help us better understand sand dunes in Earth’s deserts and the impact they might have on the environments around them as they grow or otherwise change.
As an associate team member of the Cassini Radar Science Team, Radebaugh has co-authored dozens of other related articles published in top-ranked journals. She and her students have traveled around the world looking at dunes to better understand those throughout the solar system (including methane dunes recently discovered on Pluto).
Additionally, Radebaugh is one of a dozen or so scientists on the Dragonfly project, a finalist for NASA’s next $850 million New Frontiers mission. Twelve missions were originally submitted, and Dragonfly and one other finalist received funding from NASA this year for further study and development (the winning mission will be selected in 2019).
Dragonfly would send a rotorcraft lander, a kind of helicopter, to Titan to “one, understand the organic cycle on Titan as it relates to chemistry that leads to life, and two, investigate how liquids, methane and subsurface water may interact with the surface and enable biotic or pre-biotic processes,” said Radebaugh.