Recurring slope lineae on Mars, satellite image. The streaks are structures called lineae, of a type known as recurring slope lineae (RSL). They are thought to be formed by seasonal flow of water, a small remnant of much larger volumes of water that existed in the past. These lineae are in Juventae Chasma, part of the larger Valles Marineris canyon system. These observations were made by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO) spacecraft. Image published in 2014.