A Viking close-up of intersecting grooves on the left rear flank of Phobos. The right field appears to be more smoothed than that on the left. We can assume it is older, created during an earlier maneuver.

 

Viking image of the improbably huge Crater Stickney on the end of Phobos
that points almost directly toward Mars. It is extremely unlikely another
asteroid could have impacted coming from that direction.

 

Viking image from the lower front right side of Crater Stickney. Long
grooves traverse the length of the body. Revealing images such as this are
not found in any mission releases since.

 

NASA stretched some Viking images such that Stickney was drastically
distorted, misrepresenting its true nature. Was it intentional?

 

Probably the most striking of Viking images of the grooves is this early one
on which NASA used a heavy contrast to bring out the markings. While still
dramatic after all of these years, it is rarely found today in publications
or on the internet. At some point they surely regretted this release.