OpenEV is a freeware program that can open and display these large files in the new JPEG2000 format.
Download it here:

FWTools: Open Source GIS Binary Kit for Windows and Linux.
http://fwtools.maptools.org/

Install the full FWTools not just OpenEV to get it to work.
It is pretty fast and does not require overly large amounts of RAM; my PC has "only" 500 Mbytes.
It is not overly user friendly however. It took several tries to get it to crop a portion of the image.
I attached a portion of the image around "Sputnik" crater.
I can't say this is any more revealing than the images already released.
There is a smaller crater below and to the right of Sputnik that looks rather similar to it.
Also to the right of Sputnik there appears to be a small protruding shape with a dark spot on the top.
Perhaps this could be a vent? Or just a mound with dark material on the top.

Bob Clark