On Saturn’s moon Titan, lakes gather beneath an orange haze. Their liquid is methane and ethane, compounds familiar to us as gases. Ellen Stofan helped establish that these lakes existed, recognizing shorelines in radar images sent home by Cassini.
I photographed Ellen at the National Academy of Sciences in Washington, D.C., in 2026. We talked about the Smithsonian and the state of science, as well as planetary exploration and black holes. She had spent years investigating distant worlds, then led institutions that bring those discoveries to the public. Her experience gave us plenty to talk about, including how discoveries reach people beyond the research community.
Her work on Titan involved the problem of seeing through its atmosphere. Ordinary cameras could reveal little of the surface beneath the dense haze. Cassini’s radar could penetrate it, returning measurements that scientists assembled into images of the terrain.
During a July 2006 flyby, the spacecraft recorded more than seventy-five dark patches near Titan’s north pole. Ellen led the paper reporting the findings in 2007. The patches returned very weak radar echoes, consistent with smooth liquid surfaces. Channels ran into them. They occupied depressions with recognizable shorelines. Some appeared full; others were partly empty or dry.
Together, those observations provided convincing evidence of lakes. They also suggested a cycle linking the atmosphere and the ground, with rain or liquid beneath the surface replenishing the basins. Titan’s extreme cold allowed methane and ethane to play roles that water plays here.
The resemblance is extraordinary. A geologist could recognize a drainage channel or an empty lake bed on a moon of Saturn, then use it to ask what had happened there. The materials and temperatures were different, but gravity still drew liquid downhill. Landscapes could be compared across that immense distance.
Ellen also studied Venus, using radar to investigate geology hidden beneath thick clouds. Her research involved reconstructing volcanic activity from the landforms it left behind, learning to read a landscape she could not visit. A ridge, depression, or flow pattern could offer evidence of events long past.
As NASA’s chief scientist from 2013 to 2016, she advised on research across the agency. In 2018, she became the first woman to lead the Smithsonian’s National Air and Space Museum. She became under secretary for science and research in 2021, overseeing the Smithsonian’s science museums and research centers.
Titan’s partly empty lakes suggest liquid levels rising and falling, a landscape changing beneath the haze. Ellen helped turn distant radar echoes into a place we could begin to imagine: somewhere with shores.
