Its surface, peppered with vast volcanoes, such as Olympus Mons, and rift valleys, such as Valles Marineris, shows geological activity that may have persisted until as recently as 2 million years ago.
Ima atmosfero, ki je večinoma sestavljena iz ogljikovega dioksida, z atmosferskim tlakom 6,1 milibara (približno 0,6 % Zemljinega).