Reanalysis of Cassini data now suggests Titan may not host a single, deep ocean beneath its icy shell. Instead, a thick, viscous slushy layer with tunnels and pockets of meltwater near a rocky core explains the observations better. Cassini, which began in 1997 and operated for nearly two decades, provided the gravity and radio measurements used in the study.
Earlier work in 2008 inferred a deep internal ocean from measurements of how Titan deforms under Saturn's gravity. The new team, publishing in Nature and led by NASA with contributions from Baptiste Journaux and Ula Jones at the University of Washington, revisited those measurements and the underlying models. They found Titan's shape change lags about 15 hours behind the peak of Saturn's pull; the delay and the amount of energy dissipated inside Titan are larger than expected for a global ocean but consistent with a viscous slushy layer. The team tracked the delay by following the frequency of radio waves from Cassini during fly-bys, and experimental data on water and minerals at extreme pressure helped interpret the gravitational signal.
The revised interior model affects habitability expectations. Pockets of freshwater in slushy regions could reach about 68 degrees Fahrenheit, and nutrients would be more concentrated in small volumes than in a vast ocean, broadening the range of potentially habitable environments. Journaux is on the team for NASA's Dragonfly mission to Titan, scheduled for launch in 2028; data from that mission could test the slush model and help determine whether conditions for simple life exist.
- Study published in Nature
- Coauthors from several institutions
- Funding: NASA, Swiss National Science Foundation, Italian Space Agency
Difficult words
- reanalysis — new analysis of existing data or results
- viscous — thick and slow-flowing liquid or material
- slushy — partially melted ice mixed with liquid water
- dissipate — to lose energy gradually, often as heatdissipated
- fly-by — a close spacecraft pass near a planetfly-bys
- habitability — the likelihood that an environment can support life
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What kinds of measurements from the Dragonfly mission would best test the slush model, and why?
- Do you think small, warm pockets in a slushy layer are more promising for simple life than a global ocean? Give reasons.
- How might concentrated nutrients in small volumes change the chance of life compared with a vast ocean?
Related articles
New acid-free way to recycle lithium-ion batteries
Researchers at Rice University developed a two-step FJH-ClO process that separates lithium and other metals from spent batteries. The lab-scale method recovers valuable materials with less energy, fewer chemicals and less wastewater.
