University of Idaho doctoral student Rajani Dhingra spends her time researching images from Cassini — a spacecraft sent by several space agencies to study Saturn and its moons.
While observing an image from June 7, 2016, Dhingra noticed an anomaly that could signal the start of summer in Titan’s northern hemisphere.
“Titan is a window to past Earth,” Dhingra said. “We’re really looking back in time when we’re looking at Titan. It helps us understand our own Earth, how we evolved.”
Jason Barnes | Courtesy
Dhingra and Department of Physics Associate Professor Jason Barnes agreed that studying Titan allows researchers to better understand how life on Earth evolved. Barnes said if life exists in the solar system outside of Earth, Titan is where it most likely resides.
Titan — Saturn’s largest moon — has a water cycle of its own. Instead of water, however, methane rains from the sky. Titan is home to methane lakes and rivers, but most liquid remains hidden underneath the moon’s thick shell of ice.
According to Dhingra, rainfall on Titan changes with the seasons. During Titan’s summers, researchers like Dhingra expect to find clouds and rainstorms. Dhingra said there was little rain to be found during the beginning of what was supposed to be summer in Titan’s northern hemisphere.
“When Cassini went on the Titan system, the south pole of Titan was in summer. What we saw was dense, dense clouds and a whole cloud system. We all just saw rainfall. It was amazing — such an active south polar summer,” Dhingra said. “Then — after seven years — there was a vernal equinox. We expected north polar summer. Here, we didn’t see anything. No clouds, no cloud cover, let alone rainfall. Nothing.”
Rajani Dhingra | Courtesy
The image from June 7 told a different story. Dhingra described the surface of Titan in the image as similar to a wet sidewalk. According to Dhingra, the anomaly faded quickly — most likely evaporated, she said — and the following images showed little evidence of rain.
“What we think is going on is that the surface is suddenly super bright and we think that might be attributed to the surface being wet,” Barnes said. “(When it’s) at just the right wavelength, the sun is shining directly on the surface, and when it’s wet, (the surface) reflects the sun rather strongly and provides that strong, bright return, so that’s what we think is going on.”
While Cassini crashed in 2017, Dhingra and her team — which represents 12 institutions and universities in addition to UI according to a press release — continue to examine and interpret data from the spacecraft. The team published a paper in the journal Geophysical Research Letters on Jan. 16, 2019.
Dhingra — who described working on this project as “a dream come true” — will focus on figuring out the remainder of the story with Cassini while Barnes said he has begun working on a new project called Dragonfly. Dhingra said she wants to encourage others to pursue research just as she did.
“I want people to know that if you really want to do (something), just stick to it, just do it, it will happen,” Dhingra said. “It has to happen.”