The Cassini mission, which began in 1997 and lasted nearly 20 years, collected extensive data about Saturn and its moons. Titan is the only world besides Earth known to have liquid on its surface; that surface liquid is methane and Titan's temperature is extremely low.
Earlier work in 2008 used measurements of how Titan deformed under Saturn's gravity to argue for a deep internal ocean. The new study, published in Nature and led by NASA with collaborators from the University of Washington, revisited those measurements and the models behind them.
Researchers found that Titan's shape change lags behind Saturn's gravitational peak, and they measured that delay by tracking radio frequencies from Cassini during fly-bys. The lag and the strong internal energy dissipation are larger than expected for a global ocean but match a viscous slushy layer with tunnels and meltwater pockets. Flavio Petricca of NASA's Jet Propulsion Laboratory led the analysis, and experimental data from Baptiste Journaux's lab helped interpret the signal. The model suggests small freshwater pockets could reach temperatures suitable for life, and the Dragonfly mission planned for 2028 could test the slush hypothesis.
Difficult words
- revisit — to look at something again or reviewrevisited
- deform — to change shape because of forcedeformed
- dissipation — process of energy being lost as heat
- viscous — thick and slow-flowing, like heavy liquid
- slushy — partly frozen mixture of ice and water
- fly-by — a close pass of a spacecraft near a bodyfly-bys
- hypothesis — a proposed explanation that needs testing
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Do you think small freshwater pockets on Titan could support life? Why or why not?
- How could the Dragonfly mission test the slush hypothesis when it arrives in 2028?
- Why is it useful to re-examine earlier measurements and models, as the researchers did here?
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