A view of Mars as it might have appeared more than 2 billion years
ago, with a low-latitude ocean filling the lowland basin that now occupies
the north polar region. Topographic deformation of features that ring
the basin, which are hypothesized to be shorelines formed by an ancient
ocean, suggests that Mars experienced significant true polar wander--reorientation
of the planet relative to its rotation axis--that brought the planet
into its present rotational state. The margins of the ocean shown here
account for the topographic deformation that would have resulted from
this reorientation. Sinuous features near the top of the image are
valleys carved by large floods that may have supplied the ocean water.
The image was generated using Viking Orbiter images and topographic
data from the Mars Orbiter Laser Altimeter on board the Mars Global
Surveyor spacecraft. |
