The outer and smaller of Mars' two moons is really, really tiny, only 15 kilometers across at its widest point. (That makes it similar in size to the asetroid Gaspra, Pluto's moon Kerberos, and smaller than any of the lumpy moons of Saturn for which we have good photos from Cassini except the even smaller Methone.) It orbits close to Mars, only about 20,000 kilometers above the surface, but it's still far from any of the orbiters that we have mapping Mars from their low circular orbits. So the best pictures that we have of Deimos are still the ones from Mariner 9 and the Viking orbiters. (Viking has more detail, but Mariner 9 got the far side.)

It was pretty easy for me to find the data for this one because, several years ago, I made myself a cheat sheet: a summary of all the Viking orbiter images of Deimos. This is it; this is the data set. There may be a few other images but they're all tiny. You can see the original images for the composite above in the third row on the left. Now that I have this summary, I can grab a set of images and have fun processing without going back into the Planetary Data System. Any of you could, too -- have at them!