Europa's Freckles
Europa,
one of Jupiter's large Galilean
moons, may well possess an ocean
of liquid water hidden beneath
its
icy surface -- and so holds the
tantalizing possibility of life.
In this
image, constructed with data recorded in 1996 and 1997 by the
Galileo
spacecraft, Europa's characteristic surface
ridges and cracks
are seen along with domes and dark reddish spots
called
lenticulae from the Latin word for freckles.
The
freckles are about
10 kilometers across and are believed to be
blobs of warmer ice from below that have gradually risen through the
colder surface layers, analogous to the motions in a
lava lamp.
If the freckles do represent material from deeper ice layers
closer to the hidden ocean,
future space missions to investigate
Europa's interior could sample the relatively accessible freckles
rather than drill through Europa's potentially
thick ice shell.