What significant feature do scientists strongly suspect lies beneath Callisto's icy exterior?
Answer
A vast, salty, subsurface ocean.
Beneath the surface crust of ice and rock, current scientific suspicion points toward the existence of a large ocean containing dissolved salts, potentially twice the volume of Earth's oceans combined.

#Videos
Colonizing Callisto - Third Largest Moon In The Solar System
Universe Sandbox 2 - Terraforming the Moons of Jupiter (Io, Callisto ...
Related Questions
Why is Callisto often considered the most favorable Galilean candidate regarding Jovian radiation?What surface characteristic suggests Callisto has had a geologically quiet history?What significant feature do scientists strongly suspect lies beneath Callisto's icy exterior?What gas primarily makes up the thin, wispy atmosphere currently present on Callisto?How does Callisto's surface gravity compare to Earth's gravitational pull?What major hurdle does Europa face that makes Callisto comparatively safer for surface operations?What happens to surface water on Callisto under its current atmospheric conditions?Which method is proposed for providing the necessary initial energy input to warm Callisto's surface?What inescapable reality must long-term settlers on a terraformed Callisto accept regarding gravity?What is identified as the biggest factor limiting the timeline for achieving a complete, self-sustaining terraforming of Callisto?