ESA has published some images of a crater with more than 30 kilometers (about 20 miles) across north of the large Hellas Planitia basin on the planet Mars obtained thanks to the High Resolution Stereo Camera (HRSC) instrument of the Mars Express space probe. The appearance of the crater along with the river valleys to the south indicates that at the time of impact there was groundwater near the surface. This is another indication that there was a lake in that region.