Martian chaos created by craters, lava, and water was observed by the European Space Agency’s (ESA) Mars Express in the Shalbatana Vallis, providing an in-depth look at this fascinating feature of the Red Planet’s terrain.
This channel, close to the Martian equator, the Shalbatana Vallis, stretches between the highland Xanthe Terra and the lowland Chris Panitia, carved by natural processes long ago. Even after two decades, Mars Express continues to provide scientists with stunning new details of the Martian terrain, filling in our understanding of Earth’s planetary neighbor.
Mars Express
Since its 2003 launch, Mars Express has been exploring the Red Planet with a suite of eight onboard instruments. Consisting of a lander, Beagle 2, and the Mars Express orbiter, the spacecraft has been especially prolific, mapping the Martian surface color and three dimensions at never-before-achieved resolution over the last two decades.
An earlier Mars Express video, captured in October 2025, observed the channel from beginning to end. Yet, this new image captured by the Mars Express’s High Resolution Stereo Camera (HRSC) focuses more tightly on a northern segment of the 1300-kilometer-long Shalbatana Vallis, providing exquisite, high-resolution detail on this intriguing surface feature.
Forging the Shalbatana Vallis
Scientists believe that, as large amounts of groundwater rose to the surface to flood this equatorial region roughly 3.5 billion years ago, that catastrophe produced the Shalbatana Vallis, cutting a winding path through the rock. The main valley cuts 500 meters deep, yet extends about 10 kilometers wide as it meanders across the Martian surface.
As weathering carved the valley, scientists believe this also filled it in over time. The precise materials that infilled the once-deep valley cannot be pinpointed, yet some clues exist. Researchers believe that a blue-black material in part of the modern channel is volcanic ash strewn about by Martian winds.
Unusual Terrain Features of Mars
Other valleys of Shalbatana Vallis’s type abound in the region, which is home to many marks of local volatility. On one side are the northern lowlands, relatively smooth, while the highlands to the south are heavily cratered from ancient space impacts. It also lies near Chris Planitia, likely an ancient ocean, based on its status as one of the lowest points on the Martian surface and the many outflow channels leading into it.
Often accompanying outflow channels, such as Shalbatana Vallis, are scattered rock mounds and raised blocks known as chaotic terrain. In this instance, a section of chaotic terrain appears in the images near the blue/black portion identified as likely volcanic ash. Such features are likely born in the collapse of the surface ground, as water ice below melts, creating instability. Mars Express has previously captured such features in the areas of Pyrrhae Regio, Iani Chaos, Ariadnes Colles, Aram Chaos, and Hydraotes Chaos.
Remnants of impact craters in the area now lie partially obscured by later burial, long-term wear, and even a covering of material ejected during the initial impact. Volcanic activity has, over time, flooded the regions with lava, smoothing many of these ancient features before cooling and shrinking into wrinkle ridges. Presently, a few isolated portions of the earlier surface still remain, now as hill tops scattered through the channel.
Going forward, with the help of software updates that occurred last year, ESA scientists are expected to keep Mars Express operational through 2034, providing ever more data ahead of any potential crewed landings on the Red Planet.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.