Lava tubes on Pavonis Mons
These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA's
Mars Express, show Pavonis Mons, the central volcano of the three 'shield'
volcanoes that comprise Tharsis Montes.
Full story:
http://www.esa.int/esaSC/SEM8AD9ATME_index_0.html
