Ocean, ocean, who's got an ocean?

 

Scientific American reports on the search for subsurface oceans on some of the moons of the Solar System. They may be harder to find (if they exist) than earlier thought.

New Views of Solar System Moons Complicate Ocean Worlds Theory

The article discusses two research papers about Saturn's unique moon Titan and Jupiter's white-cold moon Europa.  Titan might be less interesting than previously thought, with a slushy interior rather than an actual hydrocarbon ocean.  Europa probably still has an ocean, but it may be a lot harder to drill down to reach, considering that it might be 20 miles or so under the surface.

"New observations of Europa gathered by NASA’s Juno mission, however, suggest that the ice shell is on the thicker side of scientists’ estimates, closer to 20 miles deep—although the exact depth depends on the ocean’s saltiness.

“There have been theoretical arguments, but this is the first pretty much direct physical measurement,” says Steven Levin, project scientist of the Juno mission and an astrophysicst at JPL.

That calculation is based on data from Juno’s microwave radiometer, an instrument that was designed to peer deep into Jupiter’s atmosphere but that is now turned toward analyzing the planet’s largest moons’ internal structure, too. Remarkably, the measurement was based on only about five minutes of data because of the constraints of the Juno spacecraft’s existing orbit around Jupiter, Levin notes."

But we do have a mission that will be there in 2030, the Europa Clipper, and a European mission that will be there a year later.  It will be interesting to see what these missions can determine.

It's down there somewhere.