As if the prospect of billions of potentially habitable exoplanets wasn’t enough to get people excited, what about all those watery exo-moons too?
The question arises as the Cassini mission makes its final pass near the now famous geysers at the south pole of the moon Enceladus. The plumes are currently in darkness and so it’s a perfect time to tease out a particularly compelling aspect of the Enceladus story: how hot is the inside of the mini-moon. Earlier measurements of the water ice spray took place when the sun was on that southern pole, so this will be the first time Cassini can measure precisely how much of the already detected heat comes from the moon’s interior.
The expectation is that much of the heat does indeed come from inside, warmed substantially by tidal forces and perhaps hydrothermal vents that together serve to keep liquid a subsurface ocean all around the moon. As a result, the evolving scientific view is that tiny Enceladus, one of 63 moons of Saturn, just may have the ingredients and characteristics that put it into an improbable habitable zone.
“Step by step, we’re learning about an environment that seemed impossible not long ago,” said Cassini Mission Scientist Linda Spilker. “We know that Enceladus has some rocky core, and that it touches the liquid water. We also know that some of the compounds identified in the geysers can only be formed when rock is in contact with hot water, and that must be happening at the bottom of the moon’s ocean. All the pieces are coming together to tell us that the moon has an ocean that might be able to support life.”
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