The glamour shots of the planets that space agencies release from the various robotic missions are always gorgeous, and they usually serve as good illustrations of the science under investigation.
But sometimes it's fun to wander out on your own. Almost all of the data collected by past and current planetary missions is posted online in one form or another. Anyone is free to mine this treasure trove, and the images created by talented amateurs from unprocessed data files can be spectacular. Besides, looking through these pictures and other information almost feels like exploring the strange and beautiful alien landscapes in person. You can fly in low over the surface of Mercury or hike the canyons of Mars, one picture at a time.
Doing this isn't always easy. It can mean laborious searches through deep archives of raw data, painstaking investigations into exactly where and what was observed, and hours of image post-processing in order to create a decent-looking (and still reasonably accurate) picture.
There are, however, a few ways to cheat a little. One of my favorites is HRSCview. It's a web interface to the archive at the Freie Universitaet of Berlin that contains huge reserves of images from the High Resolution Stereo Color Imager (HRSC) on board the European Space Agency's Mars Express orbiter. This camera regularly photographs the Martian surface, and can capture details as small as 2 meters across.
The HRSCview site displays pictures from Mars that you access simply by navigating somewhat like you would using Google maps. Even better, it carries out some on-the-fly image processing in order to make sure the scenes you see are properly projected, oriented and colored in an approximately true-to-life way. The data is updated every six months and provided jointly by the Freie Universitaet and the German Aerospace Center (DLR).
Below is the result of just one expedition using HRSCview. It's a composite of half a dozen or so images obtained by clicking around in HRSCview. All I did was carefully combine the images, fill in some tiny gaps in the data by sampling the pixels immediately adjacent, and brighten the resulting picture.
It shows part of Noctis Labyrinthus, "the Labyrinth of the Night", which has to be the best place name in the entire Solar System. The feature probably formed from faulting ultimately caused by volcanic activity in Tharsis to the north. The result is a maze of canyons that would make for some amazing hiking in person, both for the interesting minerals that can be found there and just for the scenery: it must be unforgettable. When explorers on foot do brave the Labyrinth of Night, I'm sure they'll be guided by maps that will trace their earliest origins to images like these.