The images of the npc here presented are derived from the HST images
clicked and obtained from the Internet Web Site cited in the text.
The original images were taken by HST's WFPC2 on 10 March 1997 (089°Ls). The
images were press released on 20 March (see Jim BELL's IMW Newsletter at
page 2042 in #187).
The images here presented only show the north polar region (npr):
The top
image is the one seen near from LCM=160°W,
the middle near from LCM=
210°W
and the bottom one near from LCM=305°W.
The images of the npr show that the details of the npc and its
surroundings are not so different from those shown in the images obtained in
the 1970s by Mariner 9 and/or Viking Orbitors. It is very impressive to be
able to find a white spot which may be identified with the Korolev crater
(196°W, 73°N) shown already in the Mariner Map in 1972 cited in No177
p1872. Is it possible to consider that the snow on the crater has remained
iced more than twenty years?
Other details around Rima Borealis look also
the same. Thus we may be allowed to think that the npc remnant including the
rifts near summer has repeatedly shown the same aspect for a long time.
(Mk & Mn)