This image from the navigation camera (Navcam) on the mast of NASA's Mars Exploration Rover Opportunity provides a look back to the crest of Endeavour Crater's rim after the rover began descending "Perseverance Valley" on the rim's inner slope.
The Navcam took this image on July 18, 2017, during the 4,793rd Martian day, or sol, of Opportunity's work on Mars.
Wheel tracks from the top of the rim to the rover are visible above the rear solar panel of the vehicle. For scale, the distance between tracks from right-side wheels and tracks from left-side wheels is about 3.3 feet (1 meter). The knob-topped cylinder mounted at the edge of the solar panel is the calibration target for Opportunity's panoramic camera (Pancam).
Opportunity's location on Sol 4793 was a site within the upper end of Perseverance Valley that the rover reached with a drive of about 45 feet (13.8 meters) on July 7 (Sol 4782). The rover team chose this location for Opportunity to spend about three weeks during a driving moratorium for the Mars solar conjunction period. Mars solar conjunction occurs once about every 26 months when Mars passes nearly behind the sun, from Earth's perspective. The relative positions of the three bodies makes radio transmission of commands from Earth to Mars unreliable. One advantage of this chosen location for Opportunity is a slight northward tilt for the solar panels, which adds to their power output during these weeks of southern-hemisphere autumn when daily sunshine is diminishing.