Here is a bit more information on why they think these certain areas make sense as opposed to other places on the surface to look for organisms:

“We have known for a long time that Europa’s fresh icy surface, which is covered with cracks and ridges and transform faults, is the external signature of a vast internal salty ocean,” Brown says. The areas of chaos terrain show signatures of vast ice plates that have broken apart, shifted position, and been refrozen. These regions are of particular interest, because water from the oceans below may have risen to the surface through the cracks and left deposits there.

“Directly sampling Europa’s ocean represents a major technological challenge and is likely far in the future,” Fischer says. “But if we can sample deposits left behind in the chaos areas, it could reveal much about the composition and dynamics of the ocean below.” That ocean is thought to be as deep as 100 kilometers.

It is definitely ambitious, but it sounds doable.  We’re looking forward to hearing about what they find in further missions.

thanks to sciencedaily.com for the great info

thanks to NASA for the pic