Nature:
The tectonic patterns and stress history of Europa are
exceedingly complex and many large-scale features remain
unexplained. Now Paul Schenk, Isamu Matsuyama & Francis
Nimmo in this week's Nature have mapped troughs and depressions
on Europa that indicate some features are caused by 'true polar
wander'. In other words, they discovered that by re-orientating
Europa's floating outer ice shell about Jupiter's tidal axis,
and treating the surface as totally decoupled from any rocky
interior mass, the tidal forces place on this shell by
Jupiter's gravitational pull induce stress fractures seen on
the surface of the moon.These depressions also appear to be
geographically related to other large-scale bright and dark
lineaments4, 5, suggesting that many of Europa's tectonic
patterns may also be related to true polar wander.
